US3582642A

US3582642A - Asymmetrical light-reflecting screens

Info

Publication number: US3582642A
Application number: US713471A
Authority: US
Inventors: Sune Johansson
Original assignee: ELEKTRISKA EXAKTOR AB
Current assignee: ELEKTRISKA EXAKTOR AB
Priority date: 1967-03-29
Filing date: 1968-03-15
Publication date: 1971-06-01
Anticipated expiration: 1988-06-01
Also published as: FR1557548A; DK123885B; GB1187913A; DE1622846A1

Abstract

An asymmetrical light-reflecting screen for tubular fluorescent lamps has wall members parallel with the longitudinal axis of the fluorescent lamp and wall members perpendicular to the said axis, and all wall members are inclined to assumed vertical planes therethrough to reflect the light rays emanating from the fluorescent lamp only in one sense in each direction longitudinally and transversely of the fluorescent lamp.

Description

United States Patent inventor Sune Johansson Varnamo, Sweden Appl. No. 713,471 Filed Mar. I5, 1968 Patented June I, 1971 Assignee Elektriskn Alrtiebolaget Enktor Vnrnarno, Sweden Priority Mar. 29, 1967 Sweden 4246/67 ASYMMETRICAL LIGHT-REFLECTING SCREENS 6 Claims, 3 Drawing Figs.

US. Cl. 240/78,

240/41 .1, 240/4l.36, 240/46.39, 240/92 Int. Cl F21s 1/06 Field of Search 240/78, 78

(LD), 78 (LD7),4l.36,4l.l,92, 46.39, 51.11

[56] References Cited UNITED STATES PATENTS 2,837,632 6/1958 Lipscomb 240/78(LD7) 2,97l,083 2/1961 Phillips 240/78(LD7) 3,169,710 2/1965 Lipscomb... 240/78 3,390,263 6/ l 968 Lipscomb 240/78 Primary Examiner-Samuel S. Matthews Assistant Examiner-Monroe H. Hayes Attorney-Karl W. Flocks PATENTEDJUN Hem 3.582.642

' SHEET 2 [1F 2 This invention relates to a light-reflecting screen having light directing surfaces, which is intended for tubular fluorescent lamps and which comprises light-reflecting wall means extending in parallel with the longitudinal axis of the fluorescent lamp, and light-reflecting wall means extending perpendicularly to the said axis. Characteristic of the invention is that both the wall means parallel with the longitudinal axis of the tubular fluorescent lamp and the wall means perpendicular to said axis are inclined to the assumed vertical planes of the wall means. The invention thus provides an asymmetrical light-reflecting screen by which the light rays emanating from the fluorescent lamp are directed in a definite sense, resulting in an ideal work illumination with the incident light rays falling obliquely from behind and from the left with respect to the viewing direction during work.

The invention will be more fully described in the following with reference to the accompanying drawings which illustrate an embodiment, chosen by way of example, of the asymmetrical light-reflecting screen. ln the drawings:

FIG. 1 is a plan view of part of the screen;

FIG. 2 is a longitudinal section of the screen combined with a tubular fluorescent lamp;

FIG. 3 is a cross section ofthe screen combined with a tubular fluorescent lamp;

FIGS. 4 and 5 on a larger scale are a longitudinal section and a cross section, respectively, of the screen.

The light-reflecting screen consists of wall means 1 and 2 which are disposed at right angles to each other and have light directing surfaces for directing the light rays emanating from a tubular fluorescent lamp 3. The light-reflecting wall means I extend in parallel with the longitudinal axis of the fluorescent lamp 3 while the light-reflecting wall means 2 extend perpendicularly to the said axis.

In accordance with the invention, both the wall means 1 parallel with the longitudinal axis of the tubular fluorescent lamp 3 and the wall means 2 perpendicular to said axis are inclined to the assumed vertical planes of said wall means.

This means that if the lamp 3 is horizontal with the screen horizontally disposed therebcneath, the wall means 1 and 2 are inclined from the vertical, while if the lamp 3 and screen are vertical, the wall means 1 are inclined from the vertical and the wall means 2 are inclined from the horizontal; the third possibility is if the lamp 3 is disposed horizontally and the screen is disposed vertically in spaced relationship adjacent thereto, the wall means 1 are then inclined from the horizontal and the wall means 2 are inclined from the vertical.

The inclination of the wall means 1 and 2, which form the generally planar gridlike screen by intersecting one another, is quite apparent in each of the figures and may be defined in relation to the plane of the screen. Thus, when it is stated that the wall means 1 and 2 are inclined to the assumed vertical plane of said wall means, what is meant is that these walls are not truly perpendicular to the plane of the screen (e.g., see FIGS. 2-5) but are inclined at an angle from the perpendicular to the plane of the screen.

In the preferred embodiment illustrated in the drawings all light-reflecting wall means 1 are inclined in the same direction from the assumed vertical planes of the wall means, while all light-reflecting wall means 2 are inclined in the same direction from the assumed vertical planes of said wall means. As a result, the wall means 1 and 2 will reflect the light rays emanating from the fluorescent lamp 3 only in one sense in each direction with respect to the longitudinal axis and the transverse direction of the fluorescent lamp 3.

The light-reflecting wall means 1 and 2 make preferably the same angle with the assumed vertical planes of said wall means. This angle can amount to say 40. As will best be seen from FIGS. 4 and 5 which are a correct scale reproduction of the light-reflecting screen, the wall means 1 and 2 are of upwardly increasing thickness, and the surface 4 which is facing upwardly by reason of the inclination makes an angle of 35 with the assumed vertical planes of the wall means while the downwardly facing surface 5 makes an angle of 45 with the assumed vertical planes or the assumed horizontal plane of the wall means.

In addition to the surfaces 4 and 5, the wall means 1 and 2 also include surfaces 6 and 7 which are located at the upper edges of the wall means 1 and 2. Of these surfaces 6 and 7, surface 6 is inclined at an angle of 10 and surface 7 at an angle of 36 to the assumed vertical planes of said surfaces.

The light-reflecting wall means 1 and 2 are so arranged in relation to each other as to reflect the light rays from the fluorescent lamp 3 substantially in angles ranging between 60 and 15 to the vertical. To this end, the wall means 1 are spaced a distance of 20 mm. Also the wall means 2 are spaced at distance of 20 mm. The height of the screen is l8 mm., the surfaces 4 and 5 amounting to 13.5 mm. of this height. At the lower ends the wall means 1 and 2 have a thickness of say 1 mm., and in the transition between the

surfaces

4, 5 and 6, 7 they have a thickness ofS mm.

In order that the light-reflecting screen shall effectively direct the light rays in the desired directions obliquely downwardly and forwardly the surfaces of the screen are coated with a light-reflecting layer. This layer may preferably consist ofaluminum, e.g. pure aluminum.

As will be seen from FIGS. 4 and 5 the edge portions of the screen are of such a configuration that several screens can be interconnected without affecting the direction of the light rays.

The invention is not restricted to the embodiment described above and illustrated in the drawings but can be modified within the scope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A light-reflecting, gridlike screen having light-directing surfaces, intended for tubular fluorescent lamps, comprising:

a first series of light-reflecting wall means extending parallel to the longitudinal axis of the fluorescent lamp, and a second series of light-reflecting wall means disposed at an angle to and intersecting with said first series of wall means to form said gridlike screen, said second series of wall means extending perpendicularly to said longitudinal axis of said lamp, wherein both said first and second series of wall means are inclined at an angle from the perpendicular to the plane of said screen, and

wherein each of said light-reflecting wall means of said first series are inclined in the same direction, and wherein each of said wall means of said second series of lightreflecting wall means is inclined in the same direction, so that the wall means reflect the light rays emanating from the fluorescent lamp only in one sense in each direction with respect to the longitudinal axis and the transverse direction of the fluorescent lamp.

2. A light-reflecting screen as set forth in claim 1 wherein the angle of inclination from the perpendicular to the plane of said screen of said wall means of said first series and said second series is the same.

3. A light-reflecting screen in accordance with claim 2 wherein said angle of inclination is about 40 from the perpendicular to the plane of said screen.

4. A light-reflecting screen in accordance with claim 3 in which the wall means are of upwardly increasing thickness, and the surface which is facing upwardly by reason of said inclination, makes an angle of about 35 from the perpendicular to the plane of said screen, while the downwardly facing surface makes an angle of about 45 from the perpendicular to the plane of said screen.

5. A light-reflecting screen as claimed in claim 1, in which the wall means are so arranged in relation to each other as to reflect light rays from the fluorescent lamp substantially at angles ranging between 60 and 15 to the vertical.

6. A light-reflecting screen as claimed in claims 5, in which the surfaces of the screen are coated with a light-reflecting layer, preferably of aluminum.

Claims

1. A light-reflecting, gridlike screen having light-directing surfaces, intended for tubular fluorescent lamps, comprising: a first series of light-reflecting wall means extending parallel to the longitudinal axis of the fluorescent lamp, and a second series of light-reflecting wall means disposed at an angle to and intersecting with said first series of wall means to form said gridlike screen, said second series of wall means extending perpendicularly to said longitudinal axis of said lamp, wherein both said first and second series of wall means are inclined at an angle from the perpendicular to the plane of said screen, and wherein each of said light-reflecting wall means of said first series are inclined in the same direction, and wherein each of said wall means of said second series of light-reflecting wall means is inclined in the same direction, so that the wall means reflect the light rays emanating from the fluorescent lamp only in one sense in each direction with respect to the longitudinal axis and the transverse direction of the fluorescent lamp.

3. A light-reflecting screen in accordance with claim 2 wherein said angle of inclination is about 40* from the perpendicular to the plane of said screen.

4. A light-reflecting screen in accordance with claim 3 in which the wall means are of upwardly increasing thickness, and the surface which is facing upwardly by reason of said inclination, makes an angle of about 35* from the perpendicular to the plane of said screen, while the downwardly facing surface makes an angle of about 45* from the perpendicular to the plane of said screen.

5. A light-reflecting screen as claimed in claim 1, in which the wall means are so arranged in relation to each other as to reflect light rays from the fluorescent lamp substantially at angles ranging between 60* and 15* to the vertical.