US3413461A - Desk lamp - Google Patents

Description

Nov. 26, 1968 v. s. WINCE 3,413,461

DESK LAMP Filed Jan. 28, 1966 2 Sheets-Sheet 1 INVENTOR V5421. ,5- M/VCE BY 7% 4 7m ATTORNEYS V. S. WINCE DESK LAMP Nov. 26, 1968 2 Sheets-Sheet 2 Filed Jan. 28, 1966 L c 7 S m Q Ma Mm mm 7m M United States Patent 3,413,461 DESK LAMP Vearl S. Wince, Newark, Ohio, assignor to Holophane Company, Inc., a corporation of Delaware Filed Jan. 28, 1966, Ser. No. 523,633 Claims. (Cl. 24081) ABSTRACT OF THE DISCLOSURE A refractor and desk lamp combination wherein the optical axis of the refractor is tilted toward a predetermined work area. Light from the source is intercepted by the refractor at higher angles on the side nearest the work area and lower angles on the side farther away from the work area. Concentric prisms on the upper portion of the refractor provide for light lowering action while concentric prisms on the lower portion of the refractor provide for light lifting action, but only on the side toward the work area. Generally vertical prisms having varying angles of light incidence provide for an asymmetric light distribution toward the work area. A base on the lamp extends in the direction of the work area and in the direction of the tilted axis to provide an indication for the user of the proper orientation of the lamp.

This invention relates to a desk lamp and to a refractor for use in combination therewith for producing light patterns directed relative to a designated work area.

Lighting for desks is generally provided by a lamp which is supported or suspended at approximately eye level, and which is placed to one side and to the front of the person seated at the desk. Known desk lamps generally consist of an incandescent lamp which is surrounded by a diffusing globe or shade, which may or may not be open at the top and bottom.

The diffusing shade spreads the light in all directions, and while this produces advantageous results in illuminating the area surrounding the luminaire, and in providing a pleasant atmosphere, it has a concomitant disadvantage in that it usually provides insufficient light over the entire work area.

It is therefore, an object of the invention to provide a desk top lamp which overcomes the disadvantages of the prior art desk top lamps in that the lamp of the invention directs a greater amount of light onto the work area of the desk, While still providing sufficient light to illuminate the surrounding areas.

It is a further object of this invention to provide a novel desk top lamp which directs the light primarily over the work area to permit optimum utilization of the light.

Further objects and features of this invention will become apparent from a reading of the specification below and the drawings in which:

FIG. 1 is a view, partly in section, of a desk top luminaire, according to this invention, shown on the left side of a work area and includes a general showing of the vertical light distribution provided by the refractor;

FIG. 2 is a top view of the embodiment shown in FIG. 1 with the lamp shade removed from the lamp to show the relative position of the refractor and includes a gen- 3,413,461 Patented Nov. 26, 1968 eral showing of the lateral light distribution provided by the light director;

FIG. 3 is a view in cross section showing the prismatic configuration of the light director and includes a more detailed indication of the vertical light distribution by indicating typical ray paths; and

FIG. 4 is a top plan view of the light director shown in FIG. 3, showing, in enlarged sections, the prismatic structure of the inner surface of the light director, and an indication of typical ray paths.

In the figures, a desk top luminaire, generally referred to as 10, is shown placed to the left of the farther edge of desk 11. Intermediate the ends of the desk is the work area, in which a work piece, such as a piece of paper 12 is disposed and over which the optimum light distribution is desired. A light source, such as an incandescent lamp 13 is placed within a light socket 14, disposed at the top end of a stand 15, which in turn is supported by lamp base 116, shown resting on the top surface of desk 11. As shown in FIG. 1, the stand 15 is supported by the base 16 at a position substantially away from the center of the base.

Conventional electrical wiring and a source of electricity, not shown, is used to provide a circuit for the lamp 13.

Surrounding the socket 14 is a holder portion 17 in which the downwardly extending portion 18 of a prismatic light director 19 is inserted.

As shown best in FIGS. 1 and 3, the optical axis O.A. of the light director 19 is tilted.

The refractor or light director 19 is an open-topped bowl in which the upper edge lies in a plane which is perpendicular to the tilted optical axis. This results in the sector nearest the work area being relatively higher than the sector away from the work area. As shown in FIG. 3, the topmost point of the sector nearest the work area, is above the light center, while the topmost surface away from the work area is below the light center of the light source 13. This construction allows the light emitted upwardly from the light source away from the work area to be unaffected by the prisms on the light director 19. This upward light is then incident only upon a diffusing light shade 23.

The tilted structure of the director '19 is therefore effective over a greater range of incident angles of light from the light source traveling toward the work area side of the light director.

The tilting of the optical axis of the light director 19 results in the normally downwardly divergent beam of light, having its axis coincident with nadir, having its axis tilted toward the work area, with a greater proportion of refracted light distributed over the work area and a correspondingly lesser proportion of refracted light distributed to the area away from the work area.

The light distribution derived by the use of the inventive re'fractor is indicated by ray traces a-e in FIG. 1 and by ray paths f-m in FIG. 2.

As shown in FIG. 3, the outer surface of the light director 19 is outwardly concave to provide uniform prismatic structure over the outer surface of the light director, while still permitting optimum prism activity at the upper portion thereof.

Referring now to the prismatic structure of the light director 19, FIGS. 3 and 4 illustrate the prismatic structure by which the inventive light director effects its desired lighting pattern. On the outer surface of light direc tor 19 are disposed concentric light lowering refracting prisms 20 which surround the entire outer surface of the light director 19 in planes normal to the tilted optical axis of the light director. As best shown by the ray paths, a, b and u, t, in FIG. 3, the concentric light lowering prisms 20 operate to lower light towards the work area. The operation of the light lowering prisms on the sector away from the work area, lowers light adjacent the work area to provide a uniform distribution of light adjacent the work area 12. Light lifting prisms 22, which are arranged concentrically in parallel planes, originate from and terminate at circumferentially spaced points, around the rim 25 on the inside of the refractor, and lie in planes normal to the optical axis CA. and parallel to the outer light lowering concentric prisms 20.

Prisms 22 form sectors of incomplete circles terminating at the bottom rim 25 of the refractor. As shown by typical ray 0, prisms 22 act to lift the light rays incident thereupon, so as to direct it toward the work area instead of letting the light pass directly down through the bottom of the light director into non useful areas.

The light lifting prisms 22 are disposed mainly on the sector of the light director nearest the work area so that the action of prisms 22 is effective to direct light onto the work piece 12.

The operation of the refracting prisms 20 is to direct the light in beam direction onto the work area, as shown by light rays a and b and in FIGS 1 and 3. Light ray 0 being already in the beam direction, therefore, passes through a section of director 19, without receiving any substantial redirection. Ray s falls on the sector away from the work area and is similarly passed through the director 19 substantially undirected.

Therefore, the combination of the light lowering prisms 20 and the light lifting prisms 22 is seen to concentrate a greater amount of useful light onto the work area than that provided by prior art lamps.

The invention also contemplates further means for directing the light toward the work area in that it provides longitudinal refracting prisms 21 (see FIG. 4) disposed on the interior of the light director 19, and which extend vertically from the plane of the uppermost lifting prism 2-2.

As shown by the enlarged sectional inserts in FIG. 4, the incident angle of the longitudinal prisms 21, is varied towards the work side sector of the light director so that the light from the light source 13 away from the work area is laterally refracted and spread as seen by typical ray paths j, i, p, 11, q, and g in FIG. 4 and ray paths 1, g, h, i, j, k, l and m in FIG. 2.

As further shown in FIG. 2, the lateral refraction provided by the longitudinal prisms 21, is asymmetrical with respect to a vertical plane passing through the light center L0. This will become evident from a study of the effect of the prisms 21 on typical ray paths, such as g and k. Ray k passes through the director 19 and receives substantially no lateral redirecton, while ray g which passes through the director at a point substantially opposed to the point at which ray k passes, is refracted by an angle of approximately 30. The effect of this asymmetrical lateral refraction is to laterally direct most of the light towards the work area 12 as most clearly shown by central ray k which receives no lateral redirection.

As shown in FIG. 1, a lamp shade 23 may be placed over the lamp. As shown in FIG. 1, shade 23 diffuses the direct light incident thereon. In a preferred embodiment, the shade is open at both the top and bottom portions thereof and is made of a translucent or diffusing material.

The off-center position of the stand 15, with respect to the base 16, provides an indication to the user of the proper orientation of the lamp with respect to the work area.

To further insure the proper arrangement of the light director 19 with respect to the work area, a longitudinal ridge 26 may be formed at the downwardly extending portion 18 on the work area side of the director. A mating longitudinal slot (not shown) is formed within the inner surface of holder 17 at the section which corresponds to the greatest extension of base 16. Thus, engagement of the ridge and slot will insure that the director is placed in proper relation to the base and the work area.

The longer portion of the base 16 extends in the direction of the work area. This off center support also serves to support the uneven weight distribution of the light director 19.

It is to be understood that the embodiments shown herein are only for purposes of example and that I wish my invention to be defined by the claims which are appended.

What I claim is:

1. A desk lamp for use in providing illumination to a work area comprising a base, a stand supported by said base, a socket adapted to receive a light source therein, a bowl-shaped refractor surrounding said socket, said refractor having concentric prism means generated about an optical axis tilted with respect to the vertical, means for lowering light, prism means for lifting light and located at the lower portion of the inner surface of said refractor, said light lifting prism means being generated in planes normal to the tilted optical axis of said refractor, longitudinal prism means disposed in the upper portion of the inner surface of said refractor for laterally deflecting light towards the work area, the angle of incidence of said longitudinal prism means being varied along said inner surface to direct the maximum amount of light in lateral directions toward the work area, said base including an extension lying in the direction of the optical axis, thereby providing an indication for the proper orientation for said lamp with respect to the work area.

2. A desk lamp according to claim 1, further comprising a diffusing lamp shade disposed over and about said lamp and said refractor.

3. For use in combination with a desk lamp for providing illumination to a desk work area and provided with a support and a socket on the support and adapted to receive a light source therein; a refractor constituting means for underlying the source of light and for redirecting light from the source asymmetrically relative to a transverse center plane therethrough in the direction of the work area on one side of the transverse plane, said refractor comprising concentric prisms displaced vertically with respect to one another, and lying in planes tilted with respect to the horizontal, the uppermost prisms of said concentric prisms lying in said tilted planes so that on the said one side said uppermost concentric prisms are above the horizontal and on the other they are below the horizontal, all of said concentric prisms being designed for direct light control and constituting means formed about an optical axis tilted with respect to the vertical for intercepting light from the source on the aforementioned one side of the transverse plane through said refractor at angles from above to below the horizontal and from above to below the center of the light source and for refracting the same downwardly at varying vertical angles toward the work area, and for intercepting light from the source on the other side of the transverse plane at angles, from below the horizontal downwardly and for redirecting the same downwardly at vertical angles away from the work area, said refractor comprising second prism means for intercepting relatively low angled light from the source on the one side of the transverse plane and for lifting the same toward the work area.

4. The refractor of claim 3 wherein said refractor includes annular means for mounting the same about the 5 socket in the lamp, said second prism means are constituted of concentric prisms generated about the tilted axis originating and ending at circumferentially spaced points about said annular mounting means and extending for the most part in the direction of the work area on the one side of the transverse plane.

-5. The refractor of claim 4 including generally vertical prism means for intercepting the radiant emission of light from said source and for refracting the same toward said Work area, the angle of incidence of said vertical prisms being varied around the tilted axis to direct the maximum amount of light in lateral directions toward the Work area.

6 References Cited UNITED STATES PATENTS 8/ 1926 Dorey 240-106 2/1930 Dorey et a1. 240106 1/1937 Rolph v 240106 5/ 1942 Ludwig 240-81 11/1962 Clark et al 240-406 FOREIGN PATENTS 5/ 1938 England.

NORTON ANSHER, Primary Examiner. RICHARD M. SHEER, Assistant Examiner.

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