US 2132784 A
Description (OCR text may contain errors)
Dct. 11, 1938. H 2,132,784
LIGHTING FIXTURE Filed May 13, 1957 2 Sheets-Sheet l E. F. GUTH LIGHTING FIXTURE Oct. 11, 1938.
Filed May 13, 1937 2 Sheets-Sheet 2 FIG]. I
Patented Oct. 11, 1938 UNITE-D ,KSTQATES PAT ENT oFFicE 2,132,784 LIGHTING FIXTURE" v Edwin F. Guth, Webster-GrovespMo. -Application'May13,1937, Serial No; 142,384 2 Claims. (01. ale- 93) .lf his' invention relates to "lighting fixtures, and with regard to certain more:specific features, to electriclighting fixtures.
Among-the several objects of the invention may ;;be nOtedtheprovision of an electric light fixture whichgprovides light of relatively great intensity but without-the presence of parts which have'ahigh surface brightness, the fixture thereby being free of objectionable glare; the provision lo: of'a fixture of the classdescribe'd wherein lighttransmitting means are included which means have a virtually uniform brightness over the entire area .of the means, therei'being 'no bright spots-:associ'atedwith the light source itself; the
15,: provisionofa fixture of'the class described which transmits light from its source with maximum efliciency; the provision-of an enclosed indirect lighting fixture which has aireflector bowl much shallower than heretofore-considered vpossible without introducing objectionable glare because of unmasked-parts of the .lightxsource,:the shallower bowlmaking the fixture 'much. more sefficient and providing for a moreunifo-rm intensity of light on the ceiling above the fixture; and the provision of a lighting fixture of the class 'described which has an attractive appearance and which isrelativelysimple andeconomical inconstruction; Other "objects will be 'incpart obvious and in part pointed out hereinafter.
The invention accordingly'comprises the elements and combinations of elements, features of construction, and 'arrangementsof parts which will be exemplified in the structures hereinafter described, and the scope-of the application of whichwill'lbe indicateddn the followingclaims. In the accompanying drawings, in which are illustratedseveralof various possibleembodiments of the invention,"
Fig; -1is partlyan-elevation and partly a sec-- tion, showing an embodiment of the 'present in-,
ventiong t 'Fig.t2 is a fragmentary :plan view-of a type of glass useful in the present invention;
Figures B and 4 are enlarged cross sections 7 taken substantially along lines 3-3 and 4-4 of Fig.2;
Fig. 5 is a fragmentary plan view similar to Fig; 2, illustrating an alternative type of glass; and,. m
- Figures 6 and 7 are enlarged cross-sections taken substantially along-lines:6-6 and 1-4 of Fig.5.
Similar :reference characters indicate corresponding parts throughout the several viewsof v ditherdrawingsm i Various'types o'f light-diffusing glass have heretoforerbeenusedin electric lighting fixtures in an effort to reduce the glare of the incandescent filament of the electric liglit source. For example,
the socalled p glass, which is a glass in 52 Which'an opaque, usually White pigment is. incorporated, has been used for this purpose. Such opal glass, however, is inefiicient-inits light transmission characteristics, and furthermore it is objectionable in 'that it :has a very high surface 14 brightness when viewed by transmitted light, which surface brightness is distinctly too glary for the .comfort ofthe-humaneye. Furthermore, opal glass when positionedbefore alight source and inspected from the-opposite side, shows a 15 non-uniform brilliance or fspottiness that is objectionable, arising from the transmission of normal and more angular rays from the light source.
'Another'type of diffusing glass heretofore used 20 inrfixtures :comprises sand-blasted or etched crystakglass- ;While such glass' is-not'asinefficient as opal glass inrespectto its light transmission, it still presents the objections-of intense surface brightness and spotty, non-uniform surface 2 brightness heretofore mentioned;
Still another type-of diffusing glass heretofore used-in fixturesisthe'somalled tapestry glass, which-is glass. the surface of which is molded into a regular or irregular pattern, each element 30 of-the -pattern,*however,being of 'a relative large individual size. Tapestry glass of this type is relatively eiiicient in'its transmission of light, but is even more-objectionable than the previouslymentioned :types .of glass in that its surface brightness is'very irregular, certainregions for example, glaring to a bad degree, While other regions have relatively no brightness at all.
The present .invention -,is based upon the observation that a certain type of surface-pattern 40 impressed:- crystal -glass,--when-positioned before a relatively intense light source, has'an appearance of uniform-brightness over. its entire area, but has a relatively low entire-apparent brightness over its surface and'has a light-transmitting efliciency 45 equal-to or -greater than "that of the so-called. tapestry glass. 7 k a The glass referredto may best be described, in 'a general way, as having 'a multiplicity of rninuta closely spaced concavities impressed in its surface, the concavities being separated from each-other Joy-narrow ridges of glass. A regular pattern-of .concavities appears to be more suitable than an irregular pattern, butthe latter is by no: means excluded; Certain'forms of suitable 55.
glass will be described in greater detail hereinafter.
The characteristics of the glass thus described make it useful in almost all types of illuminating fixtures, but it is of particular utility in conjunction with a so-called enclosed indirect lighting fixture of the type shown in Fig. 1, for example.
Referring now more particularly to Fig. 1, numeral indicates a customary swivel type canopy by which the fixture is attached to the ceiling, for example. Extending downwardly from the swivel portion of the canopy I, and supported thereby, is a tube or pipe 3, which serves to mount the fixture proper. On the lower end of the tube 3 there is attached a socket 5, which.
receives an electric light bulb 1, preferably of the customary pear shape. The light bulb 1 includes the usual filament 9.
Surrounding the light bulb I is the fixture proper, which is indicated by numeral II and which will now be described. Numeral l3 indicates an open-ended cap that hangs downwardly over the socket 5, slipping, for mounting purposes, on the tube 3. Fitting closely over the cap I3 is a cylindrical ring l5, which has a plurality of J shaped slots I! at its upper periphery adapted to receive radial pins l9 mounted in the cap l3. When the pins |9 are in the front part of the J slots H, the ring is held against sliding downwardly on the cap l3, but said ring may be disengaged from the cap l3 by lifting it and rotating it in such manner as to move the pins I9 out through the lengths of their respective slots H.
The ring I5 has relieved tabs or portions 2| at its lower periphery, which are bent into clamping engagement with the upper horizontal flange 23 of a trunco-conical glass piece 25. The glass of this piece 25 is the special glass heretofore mentioned, and will be described in detail hereinafter. The lower or outer periphery of the glass piece 25 is also horizontally flanged, as indicated at numeral 21, and this flange 21 is held juxtaposed to the periphery 29 of a reflecting bowl 3| by a plurality of spring clamps 33, for example.
The reflecting bowl 3| is preferably formed of a metal, such as aluminum, the inner surface desirably having a high reflectivity. As shown, the bowl 3| is closed at its bottom, and it may well be provided with decorative ridges and grooves indicated by numerals 34.
The nature of the pattern provided on the surface of glass piece 25 is shown in greater detail in Figures 2, 3, and 4, to which attention is now directed. The glass itself is preferably of a clear, crystal type, and while the pattern is normally provided, for ease and economy of manufacture, on its inner surface, the outer surface also operates satisfactorily for the pattern impression,
so far as the light effects achieved are concerned.
Referring to Fig. 2, it will be seen that the pattern comprises a multiplicity of indented or concave ellipse-like shapes 35, arranged in close proximity in a honeycomb, frame of hexagonal pattern. The concavity along the major and minor axes of the ellipses is shown in Figures 3 and 4, respectively. The concavities 35 leave a frame or network of upstanding ridges 31 which are relatively sharp. It is important that the individual concavities 35 be relatively minute, and that they be spaced closely in order to obtain the network of ridges 31 with each edge as narrow as feasible. For example, in a satisfactory glass for present purposes, having the pattern of Fig. 2, the dimensions of the elliptical concavities 35 are:
major axes, '3/64 inch; minor axes 1/32 inch;
depth, about 1/64 inch.
Fig. 5 illustrates an alternative pattern that is also satisfactory for present purposes. The concavities 35, instead of being elliptical, are now diamond-shaped, and are arranged in a honeycomb frame of diamond-shape (or rhombic) pattern. The ridges 31 are similar to those heretofore described.
In both embodiments, the surface of the glass within the concavities 35 and around the ridges 31 is clear. Also, the opposite surface of the glass is preferably smoothly finished, as by polishing, and is likewise clear. The clarity of both sides of the glass is indicated by the fact that if such glass is laid directly against printed matter. the printed matter can readily be read therethrough. But as quickly as the glass is moved an inch or so away from the printed matter, it becomes completely diffused and is no longer even visible as printed matter, but only as a uniform diffused brightness on the glass.
In previous enclosed indirect lighting fixtures, it has been necessary to make the opaque reflector bowl corresponding to the bowl 3|, much deeper than the bowl 3| of the present invention, because it has been necessary to use the bowl edge to mask the bright neck of the bulb 1 from view by a beholder looking at the fixture from any normal angle of view. In the present invention, however, it will be noted that the bowl 3| is so shallow that its upper edge is approximately in the same plane as the filament 9 of bulb In the present'invention, accordingly' the relatively opaque bowl 3| need extend only high enough to mask the filament 9 from view by a beholder looking at the fixture from any normal angle of vision; the peculiar characteristics of the glass piece 25 operate to prevent any objectionable glare, at eye-level, from the neck of the bulb The shallower bowl 3| also makes for the effiis will be uniform over the entire surface of the glass. The efficiency of the glass as thus de scribed is exceedingly high. 'For example, the light emitted from a fixture such as that shown in Fig. 1 will frequently total more than ninety per cent of the total light emitted from the lamp. Thus, thefixture has a peculiar adaptability in that it will provide a good source of light even using a bulb 1 of relative low wattage, and thus it is an ideal type of fixture for use in connection with the'remodeling of buildings where the old wiring capacities are not sufficient safely to carry bulbs of high wattage.
The optical reasons for the unusual lighting effects produced by the glass of the present invention are not at all clear. It may be that each concavity acts as a concave lens, refracting incident light rays, regardless of their angles of incidence, into hemispheres of perfectly diffused rays.
It may be observed, upon close inspection, that most of the light transmitted through the glass appears to emerge from the ridges 31, which are much brighter than the bottomsof concavities 35. This maymean that what the observer sees is a network of light-emitting ridges with dark spaces between ridges, the size and spacing of the ridges being so minute that they blend, upon more distant observation, into a uniformly brilliant surface devoid of pattern or variations of any kind.
Regardless of the reasons, however, the present invention provides for lighting that is notably distinct and different in the respects set forth.
In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.
As many changes could be made in carrying out the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
1. An electric illuminating fixture comprising an electric light bulb providing lightrays, reflector means partly surrounding the bulb and obscuring it from direct vision, and glass means surrounding substantially the remainder of said bulb and positioned to transmit said light rays, said glass means having a surface provided with a multiplicity of closely spaced minute substantially ellipitical, curved-surface concavities, said concavities having a major axis not exceeding the order of 3/64 inch and a minor axis not exceeding the order of inch, and a maximum depth not less than the order of 1/64 inch, said concavities being arranged in a regular pattern with minute ridges surrounding the concavities and forming a network of ridges, said reflector being bowl-shaped and the said glass being conical.
2. An enclosed indirect electric illuminating fixture comprising an electric light bulb providing light rays, reflector means surrounding the lower part of said bulb and obscuring the filament thereof from direct View at a usual position of observation, and reflecting light from said bulb upwardly, and glass means surrounding the remaining, upper part of said bulb, said glass means having a surface provided with a multiplicity of minute curved-surface concavities, arranged in a pattern with minute sharp ridges surrounding the concavities and forming a network of ridges, the concavities being so closely spaced that substantially no surface except that of the ridges is presented between adjacent concavities, said concavities being of such size and shape that the apparent surface brightness of said glass means to an observer at the usual position of observation is low and uniform over the entire surface of said means, said glass means nevertheless transmitting substantially all of the light reaching it from said bulb.
EDWIN F. GUTI-I.