US2303747A - Indirect lighting fixture - Google Patents

Description

1942 F. P. KUHL INDIRECT LIGHTING FIXTURE Filed Aug. 1, 1940 3 Sheets-Sheet 1 Tan it 1 ATTORNEYS Dec. 1, 1942. F. P. KUHL INDIRECT LIGHTING FIXTURE Filed Aug. 1, 1940 I 3 Sheets-Sheet 2 IN VENTOR.

BY W "paw ATTORNEYS- Dec. 1, 1942. F. P. KUHL "2,303,747

INDIRECT LIGHTING FIXTURE 7 Filed Aug. 1, 1940 3 Sheets-Sheet 5 Patented Dec. 1, 1942 INDIRECT LIGHTING FIXTURE Frank P. Kalil, New York, N.

12.. Long corporation of New York ray lighting In Y. alllgnortosilv- 01mm n, a I

; Application August 1, 1940, Serial No. 349,082 3 Claims. (Cl. 240-18) This invention relates to that type of illumination in which the bulb has its lower portion coated with a reflecting medium such as silver to a cut-off line approximately to the level of the light source tion of the light from the source will be directed to the ceiling to give light distribution which is entirely indirect.

(filament) so that the greater por- This type of illumination has the characteristic of distributing the light laterally throughout the space to beilluminated so as to give, in a selected worlring plane lateral limits of such space (which is dependent upon the lumen strength of the light source) a uniform distribution in said selected working plane.

It is to be distinguished from an illuminating arrangement employing a clear bulb beneath a curved reflector which receives only the rays radiated upwardly directly from the source and reflects these downwardly and substantially vertically so as to concentrate only these reflected radiations in the space immediately below the My invention can be embodied into fixtures in the same way regardless of whether the bulb is supported base up or base down. The main distinction between the two structurally is that where the bulb is supported base up it is the spherical surface which is coated with the refleeting medium to a cut-oi! line approximately to the level of the light source, whereas when the toured and dimensioned so as to encroach lyuponthelightdistributioncurvesoas itself of some of the lumens to illuminate the bowl which is made translucent to effect this purpose.

toavail.

thereof, and within the chain minated shielding means be played. a

I attain the general objects of my invention by associating with the reflecting bulb to give the aforementioned type of illumination, shielding means which are generally vertically directed. In the embodiment herein disclosed, these shieldmeans take the form of one or more relatively thin annular members spaced from the bulb and from each other (where a, plurality of such members are employed) and so related as to their number, their depth or height, their position relatively to and spacing from the cut-oi! line of the bulb and from each other, as to eifect the shielding function and additionally provide for improved ventilation and convenient pull without requiring encroach upon the light that the eflect of anilluwith. my invention is the projdi'stribution curve or The general object of vention are comprising a silvered bulb, of means for preventing glare from such a bulb without interfering the eifective light distribution therefrom, the provision ting fixture of shieldfrom the underside. that can below without disturbing the fixture which a pull chain on the lamp socket is directly accessible from below the fixture.

Thes objects vention-shown in the drawings,

Figure 1 is an elevational View. partly in sec-- tion, of one embodiment of my invention wherein the bulb is su ported base up:

.;-. me is elevational view, similar to Figported base down in a lighting fixture, portions being broken away to. -disclose' the underlying.

construction;.% i-

Figure 7 is an elevational view of embodiment of my invention showing the application of my invention to a floor lamp, the bulb being broken away to disclose the underlying construction;

Figure 8 is a bottom plan view of a multiple lamp lighting fixture in which the bulbs are supported base up and in which provision is made for direct lighting as well as for'indirect lightins; and

Figure 9 is a side elevational view of the fixture of Figure 8, with portions broken away to disclose the underlying construction substantially on the line 8-9 of Figure 8, looking in the direction of the arrows.

In the illustrative embodiment of my invention shown in Figure 1, the numeral l denotes a lamp socket supported from theceiling C within which is mounted, base up, an incandescent bulb ll provided with a filament having its center of luminosity at l2, which point is positioned near, but slightly above the center of a spherically curved portion of the glass encasement of the bulb II. The lowermost outer surface areas of this spherical portion carry a reflecting coating II, which prevents passage of light from the luminous center I! in a downward direction and reflects such light back toward the luminous center I: and against the ceiling and upper portions of the walls in which the fixture is located.

The center of curvature of this spherically curved portion of the bulb encasement and the reflecting coating thereon is indicated at M, and it will be observed that the upper boundary l of the reflecting coating I2 is shown by way of example as positionedslightly above the center of-"curvature I4, while the center of luminosity is shown positioned slightly above both the boundary l5 of the casting and the center M. This construction assures a free passage of the reflected rays around the filament of the bulb H, and minimizes bombardment of the filament by these reflected rays.

The distribution curve of a bulb such as the bulb II, which type of bulb is commonly known as the silvered bow type of incandescent bulb, is shown in Figure '2 at P. This figure is a light distribution chart of conventional form in which the candle power is laid oil radially mainly to secondary- "reflections at'the face of the uncoated portions of the encasement of the bulb. In order to prevent the same I have provided a system of louvers and shields. The louvers in the embodiment of Figure 1 are in the form of concentric cylindrical surfaces arranged at appropriate levels so as to cut off direct view of the glass surface of the bulb from points of view at which such glarewould be annoying. ,Thelevel ofjthe louversds also arranged withaview toward keeping their size as small as possible consistent with adequate shielding efiects, and with the requirements of proper ventilation, and the surfaces are vertically disalong lines radiating at different vertical angles from the luminous center of the bulb. It will be observed that the spread of light is approximately 180.

Experience has shown that if a bulb such as the bulb H is positioned below a ceiling, as in posed so as to offer no obstruction to downwardly directed light and to a pendent pull chain and no places where dust can collect. At

the same time those surface portions of the louvers which are illuminated by the bulb are so disposed that such illumination is substantially uniform for the respective louvers.

The system of louvers just described is shown at l6, l1 and I8 and as will be. observed theirupper edges I9, 20 and II respectively are arranged at different levels, thatis to say in stepwise relation and they are so disposed that the said upper edges lie in the light distribution curve P' which is characteristic of the bulb II and which is drawn'to an appropriate scale. By so arranging the louvers it will be observed that those points thereof that receive the strongest illumination are spaced at a greater distance than those points that receive the lesser illumination. The relation of the candle power to the distance of the point at which it is received is in inverse proportion, so that the brightness of the inner surface of the louvers receiving this light is substantially the same for all louvers.

As an additional safeguard against glare I have shown an inverted truncated conical shield 22 surrounding the neck portions of the bulb and coaxial therewith and this shield is disposed substantially in the direction of the rays proceeding from the filaments of the bulb H, so that it has no obstructive effect on the passage of suchrays, while at the same time it shields the neck portions of the bulb from view.

if a fixture provided with a system of louvers and shields as has just been described is positioned in an ordinary sized room it will be obvious that no matter at what point the observer is positioned he cannot obtain a direct view of any of the uncoated portions of the bulb H, except where he is positioned almost immediately below the fixture. portions of the uncoated bulb surface, are, itis true, visible, but the angles at which such surface'portions are viewed is such that the glare,

fixture is seldom turned upward intov the position T necessary in order] to obtain a view of the uncoated portions of the bulb.

Figure 2, so'tha't the ceiling and wall act as reflectors serving to'redistribute the light from the bulb, the resulting illumination in the working plane, for a room of'ordinary dimensions, is substantially uniform. i

It is also foundhowever that if a silvered bowl bulb such as the bulb II is used without shielding, that, the glare from the'uncoated parts of the .bulb'is, very-annoying. This glare is due Itwill be observed that the louvers I6, l1, l8

offer no obstruction to the passage of vertical rays of light from the ceiling and further that they offer no surface on" which dust or dead in T sects con collect. The shield 22 on the other hand'while "it does offer some obstructive action to downward rays is of such smallsize and is positioned so closely to, the bulb II that its ob-xstructive effect is negligible. I Relamping is possible through the louver l6 and a pull chain, whereused, is readily hung within the shield 22 and 'the louver lt. Ventilation is ample, be-

In these last named positions cause the spacing of the louvers is sufliciently wide for the purpose.

In order to support the system of louvers and shields that I have just described I may use rods or braces 23 interconnecting the louvers I8, I1 and I8 as indicated. At an intermediate point these braces are connected by a suitable fitting 24 with arms 25 connected to a collar 28 provided with bayonet slots 21 adapted to engage pins 28 projecting inwardly from a socket cover 23. It will be observed that the fitting 24 is shown as in threaded engagement with the ends 'of the arms 25, and thereby the height of the rods 23 may be adjusted, and the position of the louvers so controlled that the most effective illumination resuits.

The fitting 24 for this purpose will be provided with an opening through which the lower ends of the arms 25 may pass and an opening at right angles to this threaded opening through which the arms 23 pass, and it may be locked in position on the threaded ends of the arms 25 by means of a pair of lock nuts 30.

It will be understood that this manner of mounting the louvers I6, I1 and I8 is illustrative of one of the many ways of mounting them.

The socket III is shown supported from the these arms are provided with brackets I24, into a slot I24a to which is fastened one end of a chain I25, the other end of which chain is connected in any suitable or preferred manner to a socket cover I28.

The socket H and the socket cover I28 are -.supported from the ceiling I33 in a more or less ceiling C in the conventional manner, as by various fittings 3I, and an outlet box 32, the details of which need not be described beyond saying,

that they serve, in additionto supporting the socket, to support the socket cover 29, and by means of arms 33 to support a canopy 34, also of conventional type.

It will be understood that the canopy 34 has primarily an ornamental function, but that if desired its surface may be treated so as to reflect light striking it. Preferably of course such refiection should be diffusing as otherwise it might result in objectionable glare at this point.

The louvers I6, I1 and I8 may be of opaque materials, such as metal, in which case they completely obstruct the light, or they may be of translucent material, so that they transmit some light, but not enough to result in glare. By using translucent materials of various coeflicients of transmission the brightness of the outer louver surfaces may be made to vary and may be made of any desired intensity.

It will also be understood that while the louvers I6, I1 and I8 have been shown as cylindrical, that louvers of other configurations may be found suitable and, for particular purposes, even preferable.

In Figure 3 a second preferred embodiment of my invention is disclosed. In this figure I have shown a bulb III, also of the silvered bowl type, supported from the ceiling in a neck up position by being mounted in a socket III). The luminous center of the bulb is indicated at H2. The center of curvature of its lower spherical portions as well as of the reflecting coating H3 is shown at I I4, and the boundary of the reflecting surface is shown at II5.

A system of concentric cylindrical louvers I-IB, III and H8 is shown disposed similarly to the louvers I6, I! and I8 of the first embodiment, with their upper edges II9, I20 and I2I disposed in the distribution curve P of the bulb II, whereby the size of the louvers may be reduced and whereby the illuminating effect already mentioned in connection with the first embodiment is attained.

The louvers H6, H1 and H8 are shown interconnected by rods or arms I23 and certain of conventional manner by fittings designated collectively by the numeral I3I, which extend into a box I32 of conventional type mounted in the ceiling I33. The fittings I3I also serve to support a canopy I34, by means of arms I35 secured to the canopy and to the said fittings.

The functioning and the advantages of this embodiment of my invention are in general the same as those of the first embodiment. It will however be noted that this embodiment does not include anything corresponding to the shield 22 of the first embodiment, wherefore it is not so well adapted for large sized rooms in whichv the bulb might be viewed at an angle very near the horizontal.

It will further be observed that adjustability of the louvers may be effected by lengthening or shortening the chain I25. For this purpose the opening I24a in each bracket I24 may be of keyhole conformation, as shown, permitting ready detachment and insertion of the chain, and a catching thereof at any desired point between adjacent balls of the chain.

The principles upon which my invention is based will be more readily understood by a refen e to gure 4 in which I have shown an embodiment of my invention in which a silvered bowl bulb 2I I, mounted neck up in a socket 2! has its reflecting portion 2I3 surrounded by a single cylindrical louver 2I6, this louver-being supported in any suitable or preferred manner as by chains 2I'I extending from the ceiling, or a part of the fixture mounted in theceiling.

When the eye of an observer is located at the point marked a, it will be observed that the lines of vision b, c, drawn toward the upper and lower edges of the louver 2I6 respectively, bound a region within which the eye is completely shielded from glare from the uncoated portions of the bulb 2| I. In fact, if the position a were the only point of observation, the dotted line of vision d, drawn from the eye to the upper boundary of the reflecting surface, might serve to limit the lower edge of the louver 2I6. However, other positions of the eye must also be considered. For instance, if the eye is positioned at the point e it will be found that in order for the uncoated portion of the bulb 2 to be invisible from this point of view, the limiting of the lower edge of the louver by the line b is required, this limiting being the same as that for the line 9 which runs from e to the upper boundary of the reflecting surface.

It will be apparent that complete shielding is effected when the eye is either at a, at e, or at any point therebetween. For lines of vision of less inclination than that from a, the neck portions of the bulb become visible, and therefore this fixture is unsuitable for all but rooms of very small extent. For angles approaching the vertical more nearly than the position e, that is, for portions of the eye directly underneath the fixture, there is also no shielding, but, as already explained in connection with the first embodiment, no shielding is necessary at these points.

In order to adapt a fixture such as shown in Figure 4 forrooms of greater extent a second louver must be added. The effect of this is to add to the shielded region a number of positions as a result of which raising the same shielding effect may be obtained with a louver of relatively small radius, whereas if the upper edge portion of the louver 2|l' were at the same level-as the upper edge of the louver 2W a much greater radius would be required for the louver to shield the vision through the same angle. This will be obvious from an inspection of Figure 5.

For reasons already mentioned in connection with the embodiments of Figures 1 and 3 the upper edges of the louvers 2l6f and2l1' are preferably disposed in the light distribution curve P The lighting fixture shown in Figure 6, which is also of the ceiling type, comprises a socket 260 within which is mounted an incandescent bulb 2" in abase down position. The luminous center of this bulb is at 212 and a reflecting coating 263 is shown on the lower or neck portion of the bulb. The boundary of the reflecting surface is shown at 265 and it will be observed that it is slightly below the luminous center 212.

A system of louvers 256, 281 and 268 corresponding in structure and function to the louvers l6, l1 and I8 of the first embodiment is shown surrounding the bulb 26!. A system of supports 213 is shown uniting the louvers and the socket cover 218 within which the socket 260 seats. The louver system is shown carried from a stem 2! by chains or the like 280. The stem 281 is shown mounted in the ceiling 284 as by means of an outlet and ceiling plate construction 285 to which the stem 28l is connected through a bayonet joint 282 so that the fixture can be readily attached as a unit to the ceiling. The details of this mounting are not illustrated as a unit and need not be described, as they may be of any conventional type.

It is to be understood that the socket 260 is suitably wired by conductors which may pass through the stem the details of such wiring not being shown. A pull chain 283 adapted for the operation of the socket is shown by way of example as depending from the socket and passing through an opening at the base of the socket cover 218.

The system of louvers 266, 261 and 268 are related positionally, as are the corresponding louvers .of the, previous embodiments, by having their upper edges positioned in the light distribution curve P of the bulb 26l, drawn to an appropriate scale, and it will be understood that their location and extent is determined according to the principles enunciated hereinabove in connection with the said other embodiments.

Since the operation of this arrangement is substantially similar to that of the previously described embodiments, detailed description thereof would appear to be superfluous. However it may be pointed out that due to the absence of a shadow thrown on the ceiling by the base of the bulb where the bulb is mounted base up, somewhat greater illuminating efliciency is obtained than in the preceding embodiment.

mouth of the reflector H2.

I In Figure 7 I have shown my invention applied to a floor lamp, the illuminating system of which comprises a bulb- 3H, mounted base 7 down in a socket positioned in the canopy 323, and having a reflecting surface 3 and surrounded by the' system of louvers 3l6, 3H and 3l8, substantially identical with the corresponding parts of the embodiment of Figure 6, and further description is therefore unnecessary. This system is carried on a stem 330 mounted in a pedestal or base 33L The upper edges of the louvers 3l8, 3|! and 3i3 are arranged in the light distribution curve or surface P of the bulb, as indicated in the drawings.

Obviously this embodiment will function similarly to the preceding embodiments, the only important distinction lying in the manner of supporting the luminous structure, this being in one case a support from and below the ceiling, and in the other case a support above the floor.

In the embodiment of Figures 8 and 9 I have shown a multi-lamp ceiling fixture in which indirect and direct illumination are combined.

The central element of the fixture is constituted by an assembly comprising a socket 4|! within which is mounted an incandescent bulb 4H. Surrounding this bulb is a reflector H2.

The bulb 4| I, as will be observed, is not provided with a reflecting coating and it is mounted base up so that, with the aid of the reflector 2 all of its light is directed downwardly. Glare is prevented by a system of louvers "3 shown in the form of concentric rings mounted in the The socket H0 is shown mounted within a socket cover or husk The assembly just described, which constitutes the direct illumination element of the flxture is shown carried by a support 4, mounted from the ceiling H5 in any suitable or preferred manner, as for example, by the arrangement designated in general by the numeral 6, and which may be of conventional type.

Suitably supported from the arrangement Hi, as by supports 6a disposed around the socket 0 are a plurality of sockets H1, enclosed if desired, as shown, by socket husks llla, three such sockets being shown, although it will be i understood that any desired number may be used. Mounted within the sockets II I are shown silvered bowl bulbs 4| 8, these being mounted in the dependent or base up position.

Supported from the socket husk lllla, as for example, by brackets 9 having a bayonet joint connection with a ring carried by said socket husk, is a system of louvers 420, 42l and 422 of progressively increasing diameter and ar-' ranged in stepped relation. The main portions of these louvers, as can be seen in Figure 8, are

\ whatever the exact configuration of these louvers they follow the principles hereinabove enunciated in connection with the other embodiments.

Their upper edges are shown located in the light distribution curve or surface P of the bulb they surround.

The louvers 420, 421 and 422 are shown con 2,303,747 nected together into a unitary structure by braces 423.

It will be understood that the fixture is wired in the conventional manner and that suitable controls of conventional type are provided. These have not been illustrated.

While I have herein disclosed several embodiments of my invention it will be understood that the same may be embodied in other forms without departing from the spirit thereof, as will be obvious to those skilled in the art.

It will further be understood that the disclosure herein is by way of illustration and is not to be interpreted in a limiting sense and that I do not limit myself other than as called for by the prior art and the terms of the appended claims.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is:

1. An indirect lighting fixture utilizing ceiling reflection, said fixture comprising an incandescent bulb of the silvered bowl type having a silvered reflecting area thereon extending from its tip to a cut-01f line approximately at the level of the filament, whereby the light beam emitted by said bulb has a spread of approximately 180, a mounting for said bulb whereby it is supported with its base uppermost and its silvered bowl lowermost in spaced relation to a ceiling, said mounting being of a character to offer no appreciable obstruction to the passage of light from the bulb to the ceiling, and shielding means supported on the fixture at the level of and in spaced relation to the bulb so as not to obstruct the passage of air currents upwardly over the bulb, said shielding means including a plurality of cylindrically arched surface portions coaxial with the vertical axis of the bulb, and each of said arched surface portions consisting only of vertical surface elements that ofier no,

appreciable obstruction to the passage of light or air in a vertical direction, and will not collect dust, and will serve to prevent glare from the bulb reaching the eye of an observer positioned to the side of and below the level of the fixture, and said arched surface portions being spaced from each other and from the bulb ina radial direction, with their upper edges at progressively higher levels as the radii thereof increase and so that the upper portion of each receives light directly from the bulb, and the said arched surface portions being at a level so that their upper edge portions intercept only a relatively small p portion of the marginal light rays of the light beam emitted by the bulb, whereby the spread of said light beam will not be materially reduced, the upper edge of each arched surface portion being at a higher level than the lower edge of the next surrounding arched portion, and there being no obstruction to the passage of light from the bulb to the ceiling other than that due to the mounting, and substantially no obstruction by the fixture to the vertical passage of light from the ceiling downward, whereby when the fixture is hung below a ceiling, the wide spread of thelight beam emitted by the bulb will result in the illumination of a substantial area of the ceiling, and substantially all the light reflected from the ceiling will be utilized in illumination of the working plane.

2. An indirect lighting fixture utilizing ceiling reflection, said fixture comprising an incandescent bulb of the silvered bowl type having a silvered reflecting area thereon extending from its tip to a cut-oil line approximately at the level of the filament, whereby the light beam emitted by said bulb has a spread of approximately 180, a mounting for said bulb whereby it is supported with its base uppermost andits silvered bowl lowermost, said mounting being of a character to oiier no appreciable obstruction to the passage of light from the bulb to the celling, and shielding means supported on the fixture at the level of and in spaced relation to the bulb so as not to obstruct the passage of air currents upwardly over the bulb, said shielding means including a plurality of rings coaxial with the vertical axis of the bulb, and each ring consisting only of vertical surface elements that ofler no appreciable obstruction to the passage of light or air in a vertical direction, and will not collect dust, and will serve to prevent glare from the bulb reaching the eye of an observer positioned to the side of and below the level of the fixture,

and said rings being spaced from each other and from the bulb in a radial direction, with their upper edges at progressively higher levels as the diameters of the rings increase and so that the upper portion of each receives light directly from the bulb, and the rings being at a level and so positioned as to intercept only a small portion of the marginal light rays of the light beam emitted by the bulb, whereby the spread of said light beam will be substantially unaffected, the relative levels of the upper edges of said rings lying in the light distribution curve of said bulb drawn to an appropriate scale, whereby the illumination of the upper portions of said rings will be substantially the same for all the rings, the upper edge of each ring being at a lower level than the lower edge of the next surrounding ring, and there being no obstruction to the passage of light from the bulb to the ceiling portion other than that due to the mounting, and substantially no obstruction to the vertical passage of light from the ceiling downward, whereby when the fixture is hung below a ceiling, a substantial area of the ceiling will be illuminated as a result of the wide spread of the light beam emitted by the bulb, and whereby substantially all the light reflected from the ceiling will be utilized in illumination of the working plane.

3. An indirect lightingfixture utilizing ceiling reflection, said fixture comprising an incandescentbulb of the silvered bowl type having a silvered reflecting area thereon extending from its tip to a cut-off line approximately at the level of the filament, whereby the light beam emitted by said bulb has a spread of approximately 180, a mounting for said bulb whereby it is supported with its base uppermost and its silvered bowl lowermost, said mounting being of a character to oil'er no appreciable obstruction to the passage of light from the bulb to the ceiling, and shielding means, said shielding means consisting of a plurality of cylindrical louvers, coaxial with the vertical axis of the bulb supported substantially at the level of the silvered bowl of the bulb, and further consisting of an inverted conical bafiie surrounding the neck portion of said bulb, said cylindrical louvers having their upper edge portions at levels rising progressively outward in a radial direction and said bafile being positioned at a higher level than said louvers, while the upper edge of each louver is at a higher level than the lower edge of the next surrounding louver, and there being substantially no obstruction to the passage of light venting glare from reaching the eye 0! an observer below and at the side of the fixture. and said fixture being free of light obstructing elements other than those enumerated, whereby substantially all 01' the light reflected trom the ceiling will be utilized for" illumination of the working plane.

FRANK P. mum

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