GB2213576A

GB2213576A - Improvements relating to road lighting appliances

Info

Publication number: GB2213576A
Application number: GB8828775A
Authority: GB
Inventors: Michael Andrew Cunningham
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-12-11
Filing date: 1988-12-09
Publication date: 1989-08-16
Anticipated expiration: 2008-12-09
Also published as: GB8828775D0; GB2213576B

Abstract

A road lighting appliance (13) has a device (16) to mask the light source (15) so that the latter shall not be directly visible at ground level in a continuous series of such lighting appliances beyond a distance from the appliance which is at least half the distance to the next appliance so that, to a driver or pedestrian whilst proceeding along the road, only the most adjacent light source will be directly visible whilst the road ahead will appear to be well lit without the direct visibility of any further light sources. <IMAGE>

Description

IMPROVEMESTS RELATING TO ROAD LIGHTING APPLIANCES THIS INVENTION concerns a device for improving the-effective illumination from road lighting appliances.

It is a well known phenomenon that the human eye will adjust, by narrowing of the iris to the presence of bright light sources with the effect that illumination by the light source of the surrounding area appears diminished. By shading the light source to interrupt a direct path to the eye, the general illumination provided by the light appears enhanced.

It is an object of the present invention to provide, on a road lighting appliance a device to occlude the light source, i.e. the bulb or illuminated tube, at least partially to reduce the distance over which the source may be viewed directly.

According to the present invention there is provided, on a road lighting appliance, a device to occlude the light source at least partially such that the latter shall not be directly visible at ground level beyond a predetermined distance from the appliance.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 diagrammatically illustrates the illumination of a lighted road, by use of a device in accordance with the invention; Fig. 2 is an end view of the upper part of a road lighting appliance incorporating the invention; Fig. 3 is a side view thereof; Fig. 4 is a view similar to Fig. 2 incorporating a modification.

Fig. 5 is a view similar to Fig. 2 incorporating a further modification.

Referring now to Fig. 1, there is illustrated a length of road having lighting appliances uniformly spaced therealong. In the example shown, the road consists of an upper level horizontal section 10, an inclined section 11 and a lower level horizontal section 12. Road lighting appliances are equally spaced along the sides of the road and each consists of an upright post 13 from which extends an upper horizontal arm 14 with a light source generally indicated at 15 at its outer end.

Schematically illustrated at 16 in Fig. 1 is a mask which surrounds the light source 15 about a horizontal axis therethrough, by such an extent that the light source is not directly visible at ground level beyond a predetermined distance given as x-y in Fig. 1. In each of a continuous series of lighting appliances as illustrated in Fig. 1 the masks 16 should limit the direct visibility of its associated light source 15 to between one half and two thirds of the distance from the next appliance. In this way, to a driver or pedestrian, whilst proceeding along the road, only the most adjacent light source will be directly visible whilst the road ahead will appear to be well lit without the direct visibility of any further light sources.Thus the overall illumination will appear to be enhanced, and in some cases this can enable the actual power of the lighting system to be reduced without apparent loss of illumination. Therefore a cost saving in operation can be realised.

Referring now to Figs. 2 and 3, the mask 16 can take many forms but in this example is shown as a hood 18 preferably manufactured by moulding from a plastics material, and attached, for example, by screws or rivets at 19 to an upper part 20 of the appliance. In this case, the light source 15 is illustrated as a gas filled tube 21, whilst the lower part of the appliance is constituted by a removable transparent lens 22 attached to the upper part 20. It will be seen that the hood 18 has sides 23 which extend downwardly alongside the lens 22, and each side 23 may incorporate an adjustable extension plate 24 whereby the vertical extent of the sides may be determined. This may be necessary, as in the example of Fig. 1, in the case of an undulating roadway, in order to set the distance beyond which each side of each individual light source shall not be directly visible.

Referring now to Fig. 4, it will be seen that the outer hood 18 and sides 23 have been replaced by an inner attachment 25, again with adjustable side extension plates 26 which lie alongside the tube 21 within the lens 22. In this case, they should be produced from a heat-resisting material to prevent them from becoming distorted.

It will be appreciated that the device may take many forms depending upon the shape and configuration of the lighting appliance but that the resultant effect should be that of masking the light source on each side thereof in the direction of the roadway.

In some cases, it may be necessary to provide the mask on one side only of an appliance and in extreme cases it may be adjustable completely to occlude the light source on one side or the other.

In the embodiment of Fig. 4 the degree of adjustment of the sides of the mask, being much closer to the light source itself, may be considerably less than in the embodiment of Figs. 2 and 3, and in any case may not be adjustable at all.

It is envisaged that the device, particularly when applied to the outer top surface of the lighting appliance can be installed very quickly and at minimal expense so that it may readily be applied to existing lighting appliances. Moreover, in the construction of new appliances the mask may be integral with the upper part of the appliance.

Referring now to Fig. 5, in another embodiment which is particularly suitable for adaptation of existing lighting appliances, the appliance is fitted with a replacement transparent bowl 30 preferably, though not essentially, produced by moulding in an acrylic material.

In this case the mask on each side of the bowl is provided by a cylindrically lenticular reflective zone 31 having its axis at right angles to the line of the roadway, in order to reflect light from the light source 21 back across the lamp and downwards to supplement the direct light from the source 21. The internal surface of the acrylic bowl in zones 31 is easily rendered reflective by a process of metalising as is well known in the plastics industry.

With this embodiment it is a simple procedure to replace existing lamp bowls which are continuously transparent from side-to-side, with an arrangmeent modified as described and illustrated.

As a further alternative, the reflective surface within the bowl may be provided on a separate plate slidable within the bowl to provide adjustment of the vertical extent of the reflective zone.

Claims

1. A road lighting appliance, including a device to occlude the light source at least partially such that the latter shall not be directly visible at ground level beyond a predetermined distance from the appliance.

2. A road lighting appliance according to Claim 1, in which said device is attached to the upper surface of the appliance in the region of the light source and extends downwardly on each of two opposed sides thereof to a level below that of the bottom of the light source.

3. A road lighting appliance according to Claim 1 or Claim 2, wherein said device is adjustable in height relative to the light source on each side thereof.

4. A road lighting appliance according to Claim 3, wherein the height of the device is adjustable by means of a plate adjustably attached thereto one on each side of the light source such that a bottom edge of said plate may be raised and lowered selectively.

5. A road lighting appliance according to Claim 1, wherein said device is contained within a housing for the light source and thus located within a removable transparent lens thereof.

6. A road lighting appliance according to any preceding claim, in a continuous series of such lighting appliances along a roadway, wherein the device occludes the. light source such that the latter shall not be directly visible at ground level beyond a position at least half of the distance to the next appliance such that to a driver or pedestrian, whilst proceeding along the road, only the most adjacent light source will be directly visible whilst the road ahead will appear to be well lit without the direct visibility of any further light sources.

7. A road lighting appliance according to Claim 1, wherein said device comprises a heat resisting mask lying alongside the light source on at least one side thereof.

8. A road lighting appliande according to Claim 1 or Claim 5, wherein said device comprises a mask on each side of the light source in the form of a cylindrically lenticular reflective surface having its axis at right angles to the line of the roadway.

9. A road lighting appliance according to Claim 8, wherein said cylindrically lenticular reflective surface comprises a zone of a transparent lens or bowl attached to the appliance around the underside of the light source, the internal surface of the bowl in said zone being rendered reflective by a process of metalising.

10. A road lighting appliance substantially as hereinbefore described, with reference to and as illustrated in Figs. 1 to 4 or Figs. 1 and 5 of the accompanying drawings.

10. A road lighting appliance according to Claim 8, wherein the reflective surface is provided by a plate slidable within a transparent lens or bowl attached to the appliance around the underside of the light source, to provide adjustment of the vertical extent of the reflective surface.