GB2220025A - Natural-light illumination enhancement assembly - Google Patents

Abstract

A natural-light enhancement assembly comprises an upright sheet 10 of transparent or translucent material profiled so as to present a series of light-refracting projections 12, the unmirrored lower surfaces of which are inclined to the mid-plane 13 of the sheet at a shallower angle than the upper surfaces. In variations, at least the upper surfaces of the projections are convex. The assembly is used to enhance illumination in a greenhouse or factory. <IMAGE>

Description

NATURAL-LIGHT ILLUMINATION ENHANCEMENT ASSEMBLY The present invention relates to an assembly for enhancing greenhouse or factory illumination using natural light.

According to the present invention, a natural-light enhancement assembly comprises an upright sheet of transparent or translucent material profiled so as to present a series of horizontally-extending light-refracting projections having light-receiving upper surfaces inclined in a first sense to the mid-plane of the sheet and less steep unmirrored lower surfaces inclined to said mid-plane in the opposite sense thereto.

In this context, by an upright sheet of material is meant one having its mid-plane either vertical or within 20 (preferably 5 ) of vertical.

Conveniently, each projection is in the form of a prism comprising flat upper surfaces inclined to said mid-plane at an included angle in the range 30 to 60 (preferably about 45 ) and/or lower surfaces inclined to said mid-plane at an included angle in the range 60 to 90" (preferably 70 ).

Alternatively, the projections may be in the form of a prism, the upper walls of which are convex e.g. having a radius of curvature of 1 mm or more.

Additionally the lower walls of the projections may also be convex e.g. having a radius of curvature of 1 mm or more, up to infinity (flat walls).

Conveniently, the mean thickness of the sheet is about 2 mm and the sheet is grooved to a depth of about 1 mm to provide said projections.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 Is a diagrammatic end view, on an enlarged scale, of a first profiled sheet according to the present invention; and Figure 2 is a diagrammatic end view, on the same scale as Figure 1, illustrating a modified form of profiled sheet according to the present invention.

Thus referring first to Figure 1 of the drawings, this shows a vertical sheet 10 of transparent plastics material profiled so as in cross-section to present a series of projections 12 each in the form of an elongate prism having a flat upper surface inclined at 45" to the mid-plane 13 of the sheet, and a lower surface inclined (in the opposite sense) at an angle of 70C to said plane.

Conveniently, the sheet is extruded acrylic e.g. "perspex" or polycarbonate.

Figure 2 illustrates a modified form of profiled sheet In which the projections 12 are slightly convex so as to spread the transmitted light and give a somewhat more uniform light distribution across the floor of the greenhouse or other structure in which the sheet is being used. In the example shown, the radius of curvature of the upper surfaces of the projections is about 2.25 mm and that of the lower surfaces about 1.75 mm but other values, preferably of 1 mm or more, can be used instead, if desired.

The broken line 14 in Figures 1 and 2, indicates the path of light incident on sheet 10 and refracted downwards as Illustrated.

The direction of light transmitted by sheet 10 can be varied by tilting the sheet anticlockwise as viewed in Figures 1 and 2 at up to 20 to the vertical but as soon as the critical angle at the rear face 16 is reached, total internal reflection will occur.

There is obviously scope for adjustment of the tilt value by rotational adjustment of the sheet to accommodate variations in sun position over the winter months.

The light enhancement assembly of the present invention is particularly suited for use in widespan greenhouses especially one-sided east-west-orientated widespan greenhouses. In this latter case, the assembly is conveniently hung from the ridge of the greenhouse to redirect light to the north of the assembly.

Claims (11)

1. A natural-light enhancement assembly comprising an upright sheet of transparent or translucent material profiled so as to present a series of horizontally-extending light-refracting projections having light-receiving upper surfaces inclined in a first sense to the mid-plane of the sheet and less steep unmirrored lower surfaces inclined to said mid-plane in the opposite sense thereto.

2. An assembly as claimed in Claim 1 in which each projection is in the form of a prism comprising flat upper surfaces inclined to said mid-plane at an included angle in the range 30 to 60 and/or lower surfaces inclined to said mid-plane at an included angle in the range 60 to 90".

3. An assembly as claimed in Claim 2 in which the flat upper surfaces are inclined at about 45" to said mid-plane.

4. An assembly as claimed in Claim 2 or Claim 3 In which the lower surfaces are inclined at about 70" to said mid-plane.

5. An assembly as claimed in Claim 1 in which each projection is in the form of a prism, the upper walls of which are convex.

6. An assembly as claimed in Claim 5 in which the upper walls have a radius of curvature of 1 mm or more.

7. An assembly as claimed in Claim 5 or Claim 6 in which the lower walls of the projections are convex.

8. An assembly as claimed in Claim 7 in which the lower walls have a radius of curvature of 1 mm or more, up to infinity (flat walls).

9. An assembly as claimed in any preceding claim in which the mean thickness of the sheet is about 2 mm and the sheet is grooved to a depth of about 1 mm to provide said projections.

10. An assembly substantially as hereinbefore described with reference to, and/or as illustrated Sn, Figure 1 of the accompanying drawing.

11. An assembly substantially as hereinbefore described with reference to, and/or as illustrated in, Figure 2 of the accompanying drawing.