GB2333587A

GB2333587A - Illumination system for a feezer

Info

Publication number: GB2333587A
Application number: GB9901271A
Authority: GB
Inventors: Anthony Bousfield
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1998-01-22
Filing date: 1999-01-21
Publication date: 1999-07-28
Anticipated expiration: 2019-01-21
Also published as: GB9901271D0; GB9801312D0; GB2333587B

Abstract

A freezer 31 capable of being internally illuminated wherein the illumination is provided by an edge-lit panel 32;33;34 of a substantially transparent material having two opposed surfaces of which at least one is within the freezer and on which a matrix of dots 12 is applied so as to produce a light piping effect internally to the freezer.

Description

Illumination System The present invention relates to an illumination system, in particular to an illumination system for use in a freezer unit.

Conventional freezers are internally illuminated by a single light source, usually a conventional incandescent light bulb, contained within a transparent or translucent housing and located on one of the intemal sides of the appliance. The light source is activated by a suitable electro-mechanical switching device on the opening of the door of the refrigerator. Improving the illumination provided by such light sources by increasing the number of the light sources within the freezer tends to increase the total heat energy dissipated. This increase in heat dissipation may produce an undesirable temperature rise within the freezer which has to be compensated for by an increased rate of cooling. The same occurs when a more intense single light source having a higher wattage is used instead of increasing the number of light sources. Furthermore, the continuous illumination of freezer cabinets, for example where the freezer has a transparent door through which its contents can be viewed, is also not desirable given the amount of heat dissipated from the light sources or more intense light source.

The state of the art in respect of illuminated edge-lit display systems, as used in vertically mounted signs, is typified by EP-A-0549679. EP-A-0549679 addresses the problem of uneven illumination of an edge-lit system by applying a matrix of dots to two opposing surfaces of a transparent sheet which is edge-lit. In effect, the dots "pipe' the light from the transparent sheet and the matrix is adjusted such that the density of the dots varies across the sheet to even out the illumination.

Surprisingly, it has now been found that the intemal illumination of a domestic freezer can be significantly improved by the use of an edge-lit panel of a transparent or translucent material on which a matrix of dots is located so as to produce a light piping effect. The illumination provided by the edge-lit panel is more evenly distributed throughout the freezer. Consequently, the freezer can be illuminated by a light source having a reduced wattage as compared to conventional light sources used in freezer illumination. A further advantage of the present invention is therefore the ability to provide continuous illumination without significantly increasing the amount of heat dissipated.

Accordingly, in a first aspect of the present invention there is provided a freezer capable of being internally illuminated wherein the illumination is provided by an edge-lit panel of a substantially transparent material having two opposed surfaces of which at least one is within the freezer and on which a matrix of dots is applied so as to produce a light piping effect internally to the freezer.

One or more edge-lit panels may be used.

The edge-lit panel may be a side panel of the freezer, which includes the rear panel, roof or lid, or the edge-lit panel may be present as a shelf on which the matrix of dots has been applied to one or, preferably, both opposed surfaces.

Preferably, the edge-lit panel is formed from acrylic sheet, such as that sold under the tradename Perspex obtainable from Imperial Chemical Industries plc.

Such sheet may include an optical brightner, such as that sold under the tradename Ovitex OB obtainable from Ciba Specialty Chemicals (UK) Limited, in order to improve the light transmittance of the sheet.

Typically, the thickness of the edge-lit panel is less than 15 mm and preferably in the range from 6 mm to 8 mm.

Preferably, a protective transparent or translucent layer is applied to the surface of the edge-lit panel that carries the matrix of dots. It is particularly preferred that the transparent or translucent layer is applied directly to the surface that carries the matrix of dots.

Preferably a light diffuser is applied to the surface that carries the matrix of dots. Particularly preferred is where such a light diffuser also acts as a protective layer as hereinbefore described. Typically, the light diffuser is formed from a sheet of suitable material such as that used for the edge-lit panel, e.g. acrylic sheet, and preferably the sheet has a thickness of up to 3 mm.

Preferably, where the edge-lit panel is a side panel of the freezer, a reflective layer is applied to the surface which opposes the surface that carries the matrix of dots. Typically, such a layer is formed from a sheet of suitable material such as white, pigmented or metallised plastics sheet or film which may have a thickness of up to 3 mm.

In a particularly preferred form when the the edge-lit panel is positioned as a side panel, the edge-lit panel is part of a lighting assembly which includes both a light diffuser and also a reflective layer.

In the present invention the matrix of dots serves to provide a conventional light diffusion effect as described in the prior art.

In order to provide a uniform distribution of light from the edge-lit panel it is preferred that the fraction of the surface covered by the dots is increased with increasing distance from the light source. Typically, the fraction of the surface covered by the dots ranges from 0.05 close to the light source and from 0.15 to 0.55, for example 0. 16, at the furthest distance from the light source. Although this increase may be achieved by increasing the number of dots per unit area, it is further preferred that the increase is achieved by increasing the diameter of the dots and hence the matrix of dots provides smaller diameter dots close to the light source and larger diameter dots further away from the light source. Typically, the diameter of a dot close to the light source is about 0.3 mm and that of a dot at the furthest distance from the light source is 0.7 mm. Particularly preferred is a matrix of dots in which there is a constant distance between the centres of adjacent dots.

Typically, the dots are white. However, non-white dots may be used to achieve a desired aesthetic effect.

A single light source may be used in the present invention. However, particularly where the distance over which the light within the panel is to be transmitted, hereinafter referred to as the transmission distance, is large, two or more light sources may be used. Preferably, where the transmission distance is large, the two or more light sources are positioned at opposing edges of the edge-lit panel. Typically, a single light source may be used where the transmission distance is in the range 450 to 600 mm. Typically, two opposing light sources are used where the transmission distance is in the range 900 to 1200 mm.

In a preferred, embodiment the light source and electrical connections to the light source are located outside the freezer cabinet, i.e. that part of the freezer which is maintained at the desired operating temperature of the freezer. In this arrangement, the edge-lit panel preferably extends through a side panel, roof panel or base panel of the freezer such that at least one edge is outside the freezer cabinet in close proximity to the light source(s). This arrangement has the advantage that the light source does not give off heat to the interior of the freezer cabinet. In addition the placement of the light source and electrics outside the freezer cabinet allows access for maintenance and protects the light source and electrics from the effects of any water seepage or ingress of ice inside the freezer. Some light sources, in particular certain types of fluorescent tube-type lighting may not operate efficiently at the low temperatures typically found within freezer cabinets and therefore locating the light source outside the freezer cabinet offers significant benefits in reliability and efficiency of the light because the light can reach its optimum operating temperature more quickly.

The illuminated panel may be inserted into the freezer cabinet through a slot cut through the insulation surrounding the cabinet and through the inner liner of the cabinet. The illuminated panel may be secured to the rear or side wall of the cabinet, with an edge of panel, e.g. 5 to 15mum extending through an adjacent panel of the freezer cabinet to the outside. The tube and electrics may then be fitted adjacent to or mounted on the part of the panel which extends out of the cabinet.

When a freezer unit is combined with a refrigerator unit or display cabinet, the same light source may be used to light a panel within the freezer and a panel within the refigerator or display cabinet. This is particularly effective when the light source is located outside the freezer cabinet.

The invention will now be further described, by way of example only, with reference to the accompaying drawings which are: Figure 1 shows part of the matrix of dots on an edge-lit panel.

Figure 2 shows a partially sectioned view through a lighting assembly which includes an edge-lit panel.

Figure 3 shows a conventional freezer indicating alternative positions for the edge-lit panel.

Figure 4 shows a conventional freezer indicating additional altemative positions for the edge-lit panel.

Figure 5 shows the positioning of the light source along the edge of the edge-lit panel.

Figure 6 shows a perspective view along section A-A of Figure 5.

Figure 7 shows a section through a freezer cabinet indicating a possible position for the edge-lit panel and light source.

In Figure 1, an edge-lit panel (11) has been printed with a matrix of dots (12) on one surface.

In Figure 2, an edge-lit panel (21) similar to that of Figure 1 and suitable for use as a side panel of a freezer cabinet is shown in a lighting assembly comprising a light diffuser (22) and a reflective layer (23).

In Figure 3, a freezer (31) is shown having three possible positions for the location of an edge-lit panel. The edge-lit panel may be located as a roof panel (32) and/or base panel (33) in which positions a lighting assembly similar to that of Figure 2 is preferably employed. The edge-lit panel may also be located as a shelf panel (34) in which position it is prefered that the edge-lit panel has a matrix of dots printed on both surfaces.

In Figure 4, a freezer (41) is shown having two possible positions for the location of an edge-lit panel. The edge-lit panel may be located as a back panel (42) and/or side panel (43).

In Figure 5, an edge-lit panel (51) is shown with a housing for a light source (52) positioned along an edge and which housing is electrically connected via a cable (53) to a power source and control mechanism (54).

In Figure 6, a view is shown along section A-A which shows that the light source (61) closely abutts the edge of the edge-lit panel (62).

In Figure 7, a freezer (71) is sectioned to show a possible position of an edge-lit panel (72) and a light source (73). The light source (73) is positioned outside the freezer cabinet on an external surface (74) of the freezer (71) and the edge-lit panel may penetrate from the external surface (74) through the foam insulation (75) of the freezer into the interior of the freezer. The light source may be positioned within the exterior housing of the freezer but ouside the freezer cabinet itself.

Claims

Claims 1. A freezer having a freezer cabinet capable of being internally illuminated wherein the illumination is provided by an edge-lit panel of a substantially transparent material having two opposed surfaces of which at least one is within the freezer cabinet, at least on of said surfaces carrying a matrix of dots so as to produce a light piping effect within the freezer.
2. A freezer as claimed in claim 1 wherein the edge-lit panel is part of a lighting assembly which includes both a light diffuser which is in contact with a surface of the panel and also a reflective layer which contacts the other opposed surface of the panel.
3. A freezer as claimed in claim 1 or claim 2 wherein the edge-lit panel has a matrix of dots applied to both opposed surfaces.
4. A freezer as claimed in any one of claims 1 to 3 wherein the edge-lit panel is formed from a sheet of plastics material.
5. A freezer as claimed in claim 4 wherein the plastics sheet includes an optical brightner.
6. A freezer as claimed in any one of claims 1 to 5 wherein on the surface of the edge-lit panel that carries the matrix of dots the fraction of the surface covered by the dots is increased with increasing distance from the light source.
7. A freezer as claimed in claim 6 wherein the increase in the fraction of the surface covered by the dots is achieved by increasing the diameter of the dots.
8. A freezer as claimed in any preceding claim wherein the edge-lit panel is a side panel of the freezer.
9. A freezer as claimed in any preceding claim wherein the edge-lit panel is a shelf.
10. A freezer as claimed in any preceding claim wherein said light source is located outside the frezer cabinet.
11. A freezer as claimed in claim 10 comprising an outer housing and an inner liner defning a freezer cabinet, said outer housing and inner liner being spaced apart and separated by an insulating material, wherein said light source is located between the outer housing and the inner lining and the edge-lit panel extends from a location adjacent said light source outside the freezer cabinet into the freezer cabinet.