US2812691A

US2812691A - Skylights

Info

Publication number: US2812691A
Application number: US358277A
Authority: US
Inventors: Robert A Boyd
Original assignee: Owens Illinois Glass Co
Current assignee: OI Glass Inc
Priority date: 1953-05-29
Filing date: 1953-05-29
Publication date: 1957-11-12
Anticipated expiration: 1974-11-12

Description

NOV. 12, R. A. BOYD SKYLIGHTS Filed May 29. 1953 :5 Sheets-Sheet 1 Zaws-ZZ' T15 5 r @550 4. Zone R. A. BOYD SKYLIGHTS Nov. 12, 1957 3 Sheet s-Sheet 2 Filed May 29. 1953 5w x117) ma: Maw/16 Fag/fer /4. 50m

United States Patent;

SKYLIGHTS Application May 19', 153,- SerialiNo. 358,277 8 Claims. (Cl.- 8 8-5 9)' This invention relates to the. utilization of daylight for lighting the interior of buildings through an. opening in-a roof or ceiling.

A major problem in the utilization. of daylight through an opening in a roof or ceiling is that the, direct sunlight from high altitudes provides. an excessive amount of light and heat. This condition is especially present during the summer months when the sun is at the higher altitudes. A proposed solution to this problem is shown in my copending application titled Skylights, Ser. No. 295,730, and filed June 26, 1952..

I It is. an' object of this invention to provide an improved skylight which rejects directsunlight from high altitudes and transmits sunlight from. low altitudes and light from the northern sky.

Other objects of the invention will appear hereinafter.

Basically my invention. comprises controlling the transmission of daylight throughan opening in a roof or ceilingby' interposin-g four interfaces, such as are present in a. hollow glass. block or in two spaced sheets of glass, in the opening. In such a structure the interfaces are conventionally termed

Faces

1, 2, 3, and 4 -Face 1 being. the interface. nearest the light, Faces 2 and 3 being the intermediate interfaces and Face 4 being the. interface nearest theinterior-of the room. According to'myi nyenti on Face 2. is provided with a series of parallel prismshaped ribs extending in a generally east-west direction. Face. 1 may be provided with a smooth surface or a series of longitudinal ribs extending in a generally north south direction.

Faces

3 and 4 are provided with ribs and/orprisms or are opalescent in order to diffuse the transmitted light into the interior being lighted. The prism: shaped ribs on. Face 2 areso constructed and arranged that direct sunlight at highaltitudes is rejected whereassunlight from the low altitudes and light from, the northern sky are transmitted.

Referring. to the accomp anying drawings:

Fig 1 is. a diagrammatic representation of the, results obtained by a skylight utilizing my invention;

Fig, 2 isa, cross-sectional elevational view of a roomshowing the excessive. sunlight from the sun at higher altitudes;-

Fig-i 3-- is a sectional view of a hollow block incorporae in'g my invention;

Fig; 4; is a cross-sectional view of a skylight comprisingtwo sheets of glass andincorporating my invention;

Fig. 5 is a fragmentary cross-sectional view of Faces I and' 2 on a greatly enlarged scale showing: the path of light rays from high altitude angles;

' 6 -i's a fragmentary oross sectional view: of Faces 1':

and 2 on' a'- greatly enlargedscale showing the path of light rays from various angles;

Fig. 7 is a cross-sectional view on a greatly enlarged scale-of a-rnodified form" of Face 2, showing the path of light" rays fromvan'ous' angles inthe sky;

" 'Fig. 8 isaseriesof curves ofg'rea't circle transmission;

obtained by testing several forms of theinvention;-

Fig. 9 is a cross-sectional view of a form of a hollow block incorporating the invention;

Fig. 10 is a plan view of Face 3 at the line 1010 on Fig. 9;

Fig. 11 is a cross-sectional view at the line 11-11 on Fig; 10;

Fig. 12 is a plan view of Face 4 at the line 12.12 on Fig. 9;

Fig. 13 is a sectional view at line 1313 on Fig. 12; and

Fig. 14 is a cross-sectional view of a modification of F ace 3.

The problem of illumination through an opening in a ceiling or roof may be illustrated by referring to a typical room. As shown in Fig. 2, sunlight passingthrough openiii'g" 20 in' ceiling 21 emanates from a southerly direction in the Northern hemisphere. At high altitude angles of the sun the" amount of light and heat emanating therefrom is excessive and undesirable. This is shown more clearly by the following table of meteorological data representing conditions at 42 North latitude:

Table I Horizontal Surface Maximum Illumination Sun Altitude,

degrees (ft-c.)-

Day of Year Sun Only Clear Sky (IL-c.)

June21 71% 9 180 May 21 and July 21 .1 Apr. 21 and Aug. 21 Mar. 21 and Sept. 21 Feb. 21 and Oct. 21. Ian. 21 and Nov. 21. Dec. 21

NWUKGEQWOO As shown in Table I, the sun altitude and sun intensity vary throughout the year, the maximum occurring during the months from April through August. Table I further indicates that the greater portion of the horizontal surface illumination is due to light from the sun and a much lesser portion is due to the clear (northern) sky.

I have found that the desired control of illumination through an opening may be obtained by interposing lour' air glass interfaces betweenthe light source, namely the sun and sky, and the interior, certain interfaces having prism shaped r'ib's thereon of particular configuration, as hereinafter described.

As shown in Figs. 3 and- 4, the four interfaces may be found in a glass block 24 or in two spaced sheets of glass, 25, 26'. In such structures the interfaces are conventionally referred to as

Faces

1, 2, 3, and 4Fa'ce' 1 being the interface nearest the light, Faces 2' and 3' being the intermediate interfaces and Face 4' being the interface nearest the interior'of the room.

Face I is" provided with a smooth surface 27, or a series. of transverse ribs. Face 2 is provided with a series of parallel pr'i's'nfshaped ribs 28, hereafter referred to as prisms, having particular configurations and extending lon itudinally in a generally east-west direction when the skylight is placed in an" opening in a ceiling orroof.

Faces

3 and 4 may beprovid'ed with ribs or prisms, 29, 31) as hereinafter described such that daylight transmitted thereto is diffused into the interior of the room.

As' shown diagrammatically in Fig". 11 a skylight incorporatingmyinvention rejects sunlight from high altitude angles (Zone II) and'transmits sunlight from low altitude angles and'light' from the northern sky (zones III).

According to my invention, sunlight froin'hi'gh altitude angles is-'refracted' by Face 1 and totally internally reflected' at Face 2 and thereby rejected. Mor'e specifically 31",:32 atanri'ncluded 'angle-=P.: When theskyliglit is placed 1n an opening in a ceiling or roof the prisms 28 extend in a generally east-west direction, the northern slope or surface 32 facing a southerly direction.

A light ray L, at sun altitude angle a, is refracted at Face 1, transmitted to and reflected from the surface 31 to surface 32, refracted through surface 32 to surface 31 of the adjacent prism, refracted through surface 31 to surface 32 and reflected therefrom to Face 1 and refracted out to the atmosphere. In a similar manner, light rays at angle a, striking the northern slope or surface 32 are totally reiected. This is represented on Fig. by the double arrows.

The incorporation of the prism structure shown in Fig. 5 m a skyli ht construction may be more clearly represented by referring to Fig. 6. It may be observed that a rayof sunli ht L. from a low altitude a is refracted at Face 1, and refracted out of surface 32. A light ray L,, re resenting li ht from the northern sky at an an le a, is refract d at Face 1 at the surface 31 toward the interior.

As shown in Fig. 6 the construction of the prisms on Face 2 reiects the sunli ht from the hi h altitude angles and permits sunli ht from the low altitude an les and lr ht from the northern sky to be transmitted toward the inten r. V utilizing twoprisms to totallv re ect the sunli ht fr m hi h altitude an les. T have found that a broad ran e of re ection of hi h altitude an les is obtained.

I have found that the an le P bet een surfaces of the prism is nref r blv 75 T have al o found that for a latitude of 2 N. the an le b. whi h the surface 31 forms with the Name of the lass is preferablv 40. After constructing the skvli ht in accordance with my in ention with the angle P=75 and the b=40, and conducting illumination tests thereon the curve of great circle illumination, shown as a solid line A in Fi 8. is obtained. This curve represents the percent of li ht transmitted at various sun altitudes f r the construction, the prisms extending in an east-west direction.

As shown in the curve in Fig. 8. there is an area or zone ran in between 52 and 7l of sun altit de at which maximum reiecti n of direct s nli ht is obtain d. It m y be n ed that t e z ne rnav extend bet een 3 and 79, n melv f r annr xim telv 31, with, substantial reiection f s'flflll hl'. V eferring to Table I. which shows sun altilltdPs "or 2 N. latitude. it may be ob erved th t this zone of 3l;- is dsufii;ientlv br d to reiect sunli ht from hi h sun a trt es om 711/2 Ag1/2 'March through September, namely,

It is apparent therefore that by utilizing a prismatic structure wh h re e ts sunl ht bv total reiection throu h two nrisms. T have been able to provide a broad area or zone of re ectinn of sun altitudes. At the same time sunli ht fr m the l wer sun altitudes and li ht from the northern skv is permitted to pass through to the interior being li h ed. V

A modification of the prisms on Face 2 is shown in Fig. 7. In this f rm the surfaces 3 34 of the rism have been Charmed in slope. without affecting the included angle P, thus hif in or rotatin the positi n of the prism about its lon itudinal or e st-west axis. The surf ce 33 forms an an le. h. with the pl ne of the glass. the an le I). being gre ter th n the an le b. in t e form of the invention sho n in ig. 6. By such a construction a li ht rav L, at an al itude an le a. is reflected and totallv internally refie ted throu h two nrisms and finallv reiected to the atmosnhere. Tn a similar manner a li ht rav striking. the north rn slrme. surface 34. from an altitude an le a. is reiected. This latter condition is shown bv the double arrows. Li ht rays L., L from low sun altitude angles and from the northern sky, respectively, are subjected to substantially the same action as in the other form of the invention shown in Fig. 6.

Contrasting the construction in Fig. 7 with that'in Fig. 6, it is found that a. is greater than 11,. This indicates that by increasing the angle [2, which one surface, the southerly slope, of the prism makes with a horizontal pIane 4 V the area or zone of rejection of light rays from high sun altitude angles may be changed and shifted to include higher altitude angles. If the construction shown in Fig. 7 were made, for example, with the angle b equal to 45, the curve of great circle transmission would be that in curve B of Fig. 8. It may be seen that the zone of rejec tion is approximately the same as in the form of the inven tion shown in Fig. 6, and represented by a curve A, but has been shifted to the right so that the zone now extends from approximately 59 to Referring to standard tables of sun altitudes it may be determined that this prism structure would be satisfactory for a latitude of 30 N. wherein the maximum sun altitude is 83 In a similar manner, by decreasing the angle b the area or zone of rejection may be changed or shifted to include lower altitude angles. For example, if b is made equal to 35 the curve of great circle transmission designated as curve C in Fig. 8 is obtained, rejecting sun altitude from 33 to 64. A reference to the table of sun altitudes indicates that the structures represented by this curve would be adequate to reject sunlight at latitudes of 48 N. wherein the maximum sun altitude is 65+.

I have also found that the zone of rejection may be broadened even further by increasing the included angle between the surfaces of the prisms on Face 2. Although maximum rejection will be obtained when P equals 75 I have found that substantial rejection will take place when P is varied between 60 and 87. It should be observed that when the angle P is changed the range of sun altitudes partially rejected is increased but the range of sun altitudes totally rejected is proportionately decreased;

I have also found that in conjunction with the prismatic structure on Face 2 a glass fiber diffusing mat 35 may be used between the spaced sheets of glass, as shown in Fig. 9. Moreover, a difiusing structure should be used on

Faces

3 and 4 in order that the light which is transmitted through

Faces

1 and 2 will be diflused into the interior; The diffusing structure preferably comprises a multiplicity of

depressed pyramids

36, 37 on

Faces

3 and 4, respectively. As shown in Figs. 10 and 12, the pyramids preferably extend in rows at angles to each other on the

respective Faces

3 and 4. The pyramids 36 on Face 3 extend diagonally across the face while the pyramids 37 on Face 4 extend in rows parallel to the sides of the face.

In addition, the pyramids on Face 3 have concave surfaces 38 whereas the pyramids on Face 4 have convex surfaces 39.

' By the above structure of the pyramid on

Faces

3 and 4, I have found that a diifusion of the transmitted light is obtained in a circular manner as contrasted to the non-circular configuration that would be obtained if a diffusing structure utilizing parallel ribs were used. 7

Fig. 14 shows a modified form of pyramids on Face 3 which is intended to aid in bringing rays of sunlight which tend to continue to travel in a northerly direction into a more nearly vertical direction toward the interior. In this structure, the pyramids 40 on Face 3 are made unsymmetrical by displacing the apex 41 of the depressed pyramid toward one side of the block in such a manner that the apex will be displaced toward the north when the sky light is placed in position in a vertical opening, I have found that this structure tends to' cause any light rays which strike Face 3 in a direction which is not normal to be corrected toward the normal. Surfaces 42 are concave.

Although best results are. obtained in my skylight struc-' I It should, of course, be understood that in practice a slight slope will be given to the skylight for drainage purposes equal on the average to Af per foot, the slope being to the north, east, or west but not to the south.

mean

The specific angles in this application are for a glass having an index of refraction of 1.52. However, it is also within the scope of my invention that light transmitting materials other than glass may be used embodying the teachings of my invention, with such modifications that might be necessary and apparent to those skilled in the art.

Modifications may be resorted to within the spirit and scope of the appended claims.

I claim:

1. The combination of a ceiling having an opening therethrough, and a skylight interposed in said opening and comprising a series of four air-glass interfaces interposed in a horizontal position between the daylight and the interior being lighted, the second interface from the light source having a series of parallel unsymmetrical prisms formed thereon extending in a generally east-west direction, each said prism having surfaces forming an included angle of approximately seventy-five degrees, one said surface of each prism forming an angle of approximately forty degrees with a horizontal plane, said forty degree surface extending upwardly in a southerly direction such that sunlight from high altitude angles is totally rejected by total internal reflection within a pair of prisms and sunlight from low altitude angles and light from the northern sky are transmitted by refraction through the prisms toward the interior being lighted, said third and fourth interfaces having light diffusing means formed thereon for diffusing the light passing therethrough into the interior.

2. The combination of a ceiling having an opening therethrough and a skylight interposed in said opening and comprising a series of four air-glass interfaces interposed in a horizontal position between the daylight and the interior being lighted, the second interface from the light source having a series of parallel unsymmetrical prisms formed thereon extending in a generally east-west direction, each said prism having surfaces forming an inclined angle ranging from 60 to 87 degrees, one said surface of each prism forming an angle of approximately 40 degrees with a horizontal plane, said 40 degree surface extending upwardly in a southerly direction such that sunlight from high altitude angles is totally rejected by total internal reflection within a pair of prisms and sunlight from low altitude angles and light from the northern sky are transmitted by refraction through the prisms toward the interior being lighted, said third and fourth interfaces having light diffusing means formed thereon for diffusing the light passing therethrough into the interior.

3. In a structure for controlling daylight, the combination comprising a ceiling having an opening therethrough 6 and a skylight interposed in said opening and comprising at least one sheet of light-transmitting material interposed in a generally horizontal position between the daylight and the interior being lighted, said sheet having a series of unsymmetrical parallel prisms on the face thereof nearest the interior, the axes of said prisms extending in a generally east-west direction, each said prism having a first surface extending upwardly in a southerly direction and a second surface extending upwardly in a northerly di rection, said second surface forming a greater angle with a horizontal plane than the angle which said first surface forms with a horizontal plane, said angles which said surfaces form with a horizontal plane, and the included angle between said surfaces ranging from to 87 such that sunlight from high altitude angles is totally rejected by total internal reflection within a plurality of said prisms and sunlight from low altitude angles and light from the northern sky are transmitted by refraction through the prisms toward the interior being lighted.

4. The combination set forth in claim 3 wherein the included angle between said first and second surfaces of each said prism is approximately 75, the angle which said first surface forms with the horizontal plane being approximately 40", and the angle which said second surface forms with a horizontal plane being approximately 5. The combination set forth in claim 3, the angle which said first surface forms with a horizontal plane being approximately 40.

6. The combination set forth in claim 3 wherein said sheet of light-transmitting material comprises one of the walls of a glass block.

7. The combination set forth in claim 6 including a mat of diffusing material interposed in parallel spaced relationship between said sheets of light-transmitting material.

8. The combination set forth in claim 7 wherein said mat comprises glass fibers.

References Cited in the file of this patent UNITED STATES PATENTS 71,475 Fitzgerald Nov. 26, 1867 595,273 Soper Dec. 7, 1897 709,849 De Man Sept. 23, 1902 719,066 Wadsworth Ian. 27, 1903 1,949,898 Cochrane et al. Mar. 6, 1934 2,179,863 Rolph Nov. 14, 1939 2,182,471 Richards Dec. 12, 1939 2,199,244 Mulford Apr. 30, 1940 FOREIGN PATENTS 355,297 France Aug. 24, 1905