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(11) | EP 0 446 068 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Illumination of a surface |
| (57) A surface (1) bearing markings or indicia, such as a street sign or an advertising
board, is illuminated by means of an elongate tubular light bulb which is mounted
relative to the surface so that it extends in a direction away from the surface, and
so that light emitted from the bulb is cast onto the surface. The light bulb is located
in an elongate housing (7) which has a first portion (9) extending in a direction
generally perpendicular to the surface (1), and a second portion (11) which is inclined
to the first portion. |
[0001] The present invention relates to the illumination of a surface on which markings or indicia are provided, such as, for example, surfaces bearing advertisements or instructions, and signs providing instructions or directions in a right way, including especially street signs.
[0002] It is known to illuminate street signs using one or more light bulbs, especially fluorescent light bulbs, which are fixed relative to the surface so that light emitted from the bulbs is cast onto the surface, generally from one edge of the surface. Such bulbs are generally positioned on the end of an arm which extends in a direction away from the signs. The bulbs are generally fixed so that they extend in a direction generally parallel to the surface of the sign which is illuminated. This arrangement has certain disadvantages. For example, the housing in which the bulbs are fixed, which has an elongate configuration, extends parallel to the surface of the sign which is illuminated, and can provide a significant obstruction to visual inspection of the sign. Furthermore, for satisfactory illumination of the sign, it is important that the distance between the sign and the light bulb is properly selected. This distance is dependent upon, amongst other things, the size and shape of the sign, and the desired degree of illumination. In order to provide satisfactory illumination for a wide range of signs, it is necessary for users of this illumination technique to stock a range of arms on which the light bulbs can be mounted. Maintenance of a large inventory of such arms is clearly undesirable.
[0003] The present invention provides a surface which is illuminated by one or more light bulbs which extend in a direction generally away from the surface.
[0004] Accordingly, in a first aspect, the invention provides an illuminated surface on which markings or indicia are provided, the surface having associated with it at least one light bulb which is fixed relative to the surface so that it extends in a direction generally away from the surface and so that light emitted from the bulb is cast onto the surface, generally from one edge of the surface.
[0005] The surface to be illuminated would generally be on a sign. The sign may provide information such as directions or instructions in a right of way, such as by a road which carries vehicles or by a pedestrian walkway. The surface may be located within a building or otherwise under cover. Commonly, however, the surface will be located outside.
[0006] The surface which is illuminated by the light bulb will generally be planar. However, the invention also finds application in the illumination of surfaces which are non-planar. For example, the surface may be almost planar, deviating from true planarity to only a small extent, for example to make the markings or indicia on it easier to read. Alternatively, the surface might deviate from planarity more significantly, for example forming part of a substantially spherical or cylindrical object. Indeed, the invention finds particular application in the illumination of a cylindrical body which has indicia or markings on its curved surface. Such indicia or markings might, for example, be advertisements. More than one light bulb may be provided around the perimeter of the cylindrical body.
[0007] The markings or indicia on the surface may be provided in a reflective material, to assist inspection thereof.
[0008] The provision of one or more light bulbs fixed relative to a surface to be illuminated in such a way that the bulb or bulbs extend in a direction away from the surface has certain advantages. In particular, the housing in which the bulbs may be located, which is generally elongate, is positioned relative to the sign so that only an end face of housing faces a person who wishes to inspect the sign. Obstruction of the sign by the housing is therefore minimised. Furthermore, it has been found significantly that satisfactory illumination of the surface is markedly less dependent on the distance between the surface and the light bulbs, since the bulbs themselves extend away from the surface to a significant degree. It has therefore been found that signs with a wide range of sizes and shapes can be illuminated satisfactorily using a significantly reduced number of arms or housings by which light sources are mounted on posts. The inventory of components required to be maintained by installers of street signs and other signs can therefore be reduced significantly.
[0009] Another advantage of the present invention is that the housing within which the bulb or bulbs are mounted may also serve the function of the arm which extends between the bulb or bulbs and the surface to be illuminated as a single integral component. This enhances the rigidity and strength of the component, reducing the likelihood of damage, whether accidental or intentional.
[0010] The angle between the axis of the bulb and the plane of the surface to be illuminated would generally be somewhat less than 90° so that light emitted from the sign is cast onto the surface. Preferably, that angle is less than 85°, more especially less than 80°. Generally, that angle will be greater than 60°, in order to minimise obstruction to inspection of the sign, and preferably the angle will be greater than 75°. It is particularly preferred that that angle is about 78°.
[0011] Generally, the light bulb will be mounted spaced apart from the surface to be illuminated. The light bulb will generally be mounted in a housing which extends between the bulb and the surface. Preferably, the housing has a first portion which extends directly away from the surface, the angle between the surface and the first portion of the housing being about 90°. The housing may have a second portion which is at an angle to the first portion, on which the bulb is mounted. The second portion will be inclined to the surface to be illuminated, so that light emitted from the bulb is cast onto the surface. The bulb may be mounted on a reflective plate by which light emitted from the bulb is reflected onto the surface to be illuminated.
[0012] More than one bulb may be provided for illumination of the surface. For example two bulbs may be provided, and may be mounted on a plate which may optionally bevelled to facilitate dispersion of light over a large area.
[0013] When viewed from beyond the edge of the surface from which light is cast onto the surface, for example when viewed from above the surface when the light bulb is positioned above the surface, the bulb will generally be positioned so that the angle between the bulb and the surface is about 90°. However, that angle could be less, for example as little a 75° or even as little as 60° or less in some circumstances, for example, a cluster of two or more bulbs may be provided in an array, for example a V-shaped array.
[0014] Furthermore, a cluster of bulbs may be arranged around a body having indicia or markings on its side walls, the bulbs serving to illuminate those side walls. For example, a cluster of four bulbs, extending perpendicularly to one another, may be provided to illuminate each of the four walls of a pillar having a square or rectangular cross-section and advertisements or directions or other markings on its four side walls.
[0015] Generally, the lights bulbs will be mounted on a post which extends generally parallel to the surface which is to be illuminated. Commonly, the post will be located behind the surface, and a housing will extend from the post, on or in which the light bulb or bulbs are provided. In many applications, the surface will be provided on a sign which is mounted on the same post as the light bulb. When the sign is relatively small, it can be mounted just on that post on which the light is mounted. When the sign is somewhat bigger, it may be necessary to mount it between two or more posts. In this event, lights may be provided on each of the posts on which the sign is mounted, or on separate posts.
[0016] A photo electric control device may be provided, associated with the or each light bulb, for control of the illumination of the surface dependent on ambient light conditions.
[0017] The light bulbs will generally be provided within a rigid housing which can provide suitable physical protection. The body may be formed from polymeric material, but it will generally be preferred that it be formed from a metal such as steel. The housing will generally include a transparent glazing panel through which light emitted from the bulb or bulbs may be transmitted. The material of the glazing panel will generally be selected for a required degree off impact resistance, and for this reason, polymeric materials such as polycarbonates will generally be preferred. The housing may include a reflective plate on which the bulb or bulbs are mounted, which may be rendered reflective by a coating of a white paint or enamel. The housing may include appropriate electric circuitry for the bulb or bulbs, including, for example, fuses, switches, and photo electric control devices. The housing will preferably be arranged to prevent ingress of contaminants, especially when the surface to be illuminated is exposed to contaminants. For example, the housing will preferably include a seal to prevent ingress of moisture, dust particles, and insects.
[0018] Another advantage of the present invention is that the housing within which the bulb or bulbs are mounted and the arm which extends between the bulb or bulbs and the surface to be illuminated can be provided as a single integral component. This enhances the rigidity and strength of the component, reducing the likelihood of damage, whether accidental or intentional.
[0019] Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is an isometric view of a sign mounted on a post which is illuminated by tubular light bulbs located within a housing;
Figure 2 is a side view of the sign shown in Figure 1;
Figure 3 is a cross-section through the housing shown in figures 1 and 2, taken on the line A-A in Figure 2;
Figure 4 is a top view of the sign shown in Figure 1;
Figure 5 is a side view of a cluster of two light bulbs which can be used to illuminate a sign;
Figure 6 is a top view of a cluster of two light bulgbs which can be used to illuminate a sign; and
Figure 7 is a top view of a cluster of five light bulbs which can be used to illuminate the curved surface of a cylindrical body.
[0020] Referring to the drawings, Figures 1, 2 and 4 show a generally rectangular sign 1 which is mounted on a post 3. The sign has markings on its principal surface, which are provided in a reflective material.
[0021] Two tubular light bulbs 5 are provided for illuminating the sign. The light bulbs are positioned in a steel housing 7 which is fixed to the post 3. The housing 7 and the bulbs 5 are positioned so that the bulbs extend in a direction generally away from the surface of the sign which is to be illuminated, and so that light emitted from the bulbs is cast onto that surface, generally from above that surface. When viewed from above, as shown in figure 4, the angle between the housing and the sign is about 90°.
[0022] The housing includes a first portion 9 which, as can be seen in figure 2, extends in a direction generally perpendicular to the sign 1. The housing further includes a second portion 11 in whicht he bulbs 5 are mounted. The second portion 11 of the housing is inclined to the first portion 9 thereof, so that the angle between the axis of the bulbs 5 within the housing and the plain of the sign is in the preferred range of 75° to 80°. This arrangement has the advantage that the degree of illumination of the sign 1 by the light bulbs 5 is satisfactory, while inspection of the sign is not obstructed unduly by the housing 7.
[0023] The light bulbs 5 are mounted on a plate which is provided with a coating of white enamel, so that light emitted by the bulb is reflected towards sign 1. The plate is bevelled, as can be seen in figure 3. A glazing panel 15, formed from a polycarbonate material, is provided to cover the bulbs 5 within the housing. A rubber gasket 17 is provided between the glazing panel 15 and the housing 7 to prevent ingress of moisture and other contaminants.
[0024] The housing 7 contains fuses and other circuitry associated with the bulbs 5. It also includes a photo electric control 19 for control of the light bulbs 5 dependent on ambient conditions.
[0025] As shown in the drawings, the housing 7 includes a socket portion 21 in which the end of the post 3 is received. Alternative arrangements for mounting the housing 7 on the post 3 might include, eg. a side mounting arrangement in which an end of the housing is bolted onto the post, and a clamp mounting, in which a clamp is used to retain an end of the housing on post.
[0026] Figure 5 shows a cluster of two bulb housings 31,33. The housings are connected to one another so as to point in opposite directions. The cluster can be used to illumiante two opposite surfaces of a sheet, or outwardly facing surfaces of a pair of sheets which are in face-to-face relationship.
1. An illuminated surface (1) on which markings or indicia are provided, the surface
having associated with it at least one light bulb which is fixed relative to the surface
so that it extends in the direction generally away from the surface and so that light
emitted from the bulb (5) is cast onto the surface.
2. An illuminated surface as claimed in claim 1, in which the angle between the axis
of the bulb (5) and the plane of the surface (1) is less than about 85°.
3. An illuminated surface as claimed in claim 1 or claim 2, in which the angle between
the axis of the bulb (5) and the plane of the surface (1) is greater than about 60°.
4. An illuminated housing as claimed in any one of claims 1 to 3, in which the or each
light bulb (5) is mounted in a housing (7) which extends between the bulb and the
surface (1).
5. An illuminated surface as claimed in claim 4, in which the housing (7) has a first
portion (9) which extends directly away from the surface (1), and a second portion
(11), which is at an angle to the first portion so that it is inclined to the surface
to be illuminated, the bulb (5) being mounted on the second portion of the housing.
6. An illuminated surface as claimed in claim 4 or claim 5, in which the housing contains
more than one bulb (5).
7. An illuminated sign as claimed in any one of claims 1 to 6, which includes a photoelectric
control device associated with the or each light bulb (5), for control of the illumination
of the surface (1) dependent on ambient light conditions.
8. An illuminated surface as claimed in any one of claims 1 to 7, which includes at least
two light bulbs (5) which are mounted independently of one another at positions spaced
apart along an edge of the surface.
9. An illuminated surface as claimed in any one of claims 1 to 7, which includes at least
two light bulbs which are mounted in a cluster at a single point along at or towards
an edge of the surface.
10. An illuminated surface as claimed in any one of claims 1 to 9, in which the surface
(1) is generally planar.
11. An illuminated surface as claimed in any one of claims 1 to 10, in which the or each
light bulb (5) is positioned so as to cast light onto the surface (1) from an edge
thereof.