GB2204171A - Illuminated signs - Google Patents

Abstract

An illuminated sign comprises light-sources 16 in a housing 10. Apertures 18, 19 formed in one wall of the housing and defining letters or other symbols are occupied by respective tubular, transparent elements 20. One or more coloured filters 23 may be provided. The transparent elements 20 may be of circular or polygonal cross-section and contain air or coloured liquid. Alternatively, the transparent elements 20 may be solid. The sign may be illuminated by natural light instead of the fluorescent tubes 16 shown. <IMAGE>

Description

Title:"Optical mask" Description of Invention The present invention relates to a mask in which there is incorporated a light-transmitting region, whereby light can pass through the mask by way of said region. Masks of this kind are commonly used in signs, for example signs indicating the position of an exit from a building. Generally, the mask is incorporated in a housing containing a light-source and the mask comprises a piece of opaque sheet material and a piece of light-transmitting sheet material. Apertures defining the letters to be displayed are cut in the opaque sheet material and these apertures are spanned by the light-transmitting sheet material. The latter material may be coloured and thus act as a filter to filter out a part of the light which is incident on the filter from the light source.With this known arrangement, the intensity of illumination of the piece of sheet material spanning an aperture in the opaque sheet material is substantially uniform and the letter displayed is of substantially uniform brightness, throughout its area.

According to the present invention, there is provided a mask in which there is incorporated a light-transmitting element, whereby light can pass through the mask by way of said element and wherein the element has a nonuniform thickness. Parts of the mask other than the light-transmitting element may be opaque to visible light.

Variations in the thickness of the light-transmitting element cause the brightness observed when light is transmitted through the element to vary from one position to another on the element. By the thickness, I mean that dimension of the element which extends in the direction of transmission light from one side of the mask to the other side.

As compared with the letters of a known sign as hereinbefore described, letters defined by a mask in accordance with the present invention have a distinctive and striking appearance.

The light-transmitting element of a mask embodying the present invention is preferably elongated and arranged with its length transverse to the direction in which light passes through the mask. The element preferably has a curved profile, as viewed in a cross-section transverse to its length.

There may be associated with the mask a light source and a coloured filter may be interposed between the light source and the light-transmitting element of the mask. Alternatively, the mask may be illuminated by natural light, optionally through a coloured filter. In a further alternative arrangement, the light-transmitting element of the mask is coloured and therefore acts as a filter.

An example of a mask embodying the present invention, the mask being one component of an assembly which also includes a light-source, will now be described with reference to the accompanying drawing which shows a perspective view of the assembly, a part of the mask and a part of an adjacent wall of the assembly being broken away to reveal internal parts.

The assembly illustrated in the drawing comprises a housing 10 which has the form of a rectangular prism and includes a front wall I I, a rear wall 12 which is parallel to the front wall, mutually parallel upper and lower walls 13, 14 and opposite end walls, one of which is shown at 15. The end walls are incorporated in respective demountable covers which include flanges overlapping with end portions of the front, rear, upper and lower walls. The covers may be retained in position by screws or other releasable fasteners.

The walls 11 to 14 may be integral with one another or permanently connected together.

A number of electrically energisable light-sources 16 are disposed inside the housing 10 and are conveniently mounted on the rear wall 12. In the example illustrated, the light-sources 16 are constituted by rectilinear florescent tubes. Other known light-sources may be provided.

The front wall 11 comprises a flat panel 17 of sheet material which is opaque to visible light. In this panel, there are formed a number of apertures defining letters or other symbols which are to be displayed. These apertures are exemplified in the drawing by a P-shaped aperture 18 and an A-shaped aperture 19. The aperture 18 is occupied by an elongated, light-transmitting element 20 arranged with its longitudinal axis lying in a plane parallel to the face of the panel 17. The thickness of the element 20, that is the dimension measured in a direction from the rear wall 12 to the front wall II, is considerably greater than the thickness of the panel 17. The element 20 is preferably positioned to protrude from the panel 17 in both a direction inwardly of the housing 10 and a direction outwardly of the housing.The element 20 preferably occupies the aperture 18 completely. A sealant may be applied to seal the joint between the element 20 and the panel 17 around the periphery of the aperture 18.

The element 20 preferably has a substantially uniform transverse crosssection along its entire length. As viewed in cross-section, the element 20 has a curved profile. For example, when the element is in an unstressed condition, the profile may be circular. The profile may be deformed somewhat when the element is inserted into the aperture 18 so that the profile is no longer exactly circular.

The element 20 may be tubular. Thus, the element may be formed of a length of cylindrical tube. Alternatively, the element 20 may have a polygonal transverse profile, in which case the element may be tubular or solid. For example, the transverse cross-section of the element may have a rectangular external profile and a substantially circular internal profile. In a case where the element 20 is tubular, the interior of the element may be occupied by air or some other colourless medium or the interior of the tube may be occupied by a coloured medium, for example an aqueous solution of a dye. In a case where the tube contains a coloured medium or a colourless liquid, the ends of the tube are sealed. The ends of the tube are preferably sealed, even when the tube contains air.The tube may be closed at its ends by deformation of the wall, or the end of the tube may-be closed by a sealant.

The element 20 is conveniently formed by a length of an extrusion of a flexible plastics material. The plastics material may be coloured to act as a filter and filter out a port of the light incident on the element. The element 20 may be coloured by application of surface layer of coloured material, either on the outside of the element or, in a case where the element is tubular, inside the element. Alternatively, the colouring medium may be dispersed throughout the material of which the element 20 is formed.

However, in the example illustrated, the element is preferably colourless.

The element 20 comprises a rectilinear portion and a curved portion.

Alternatively, these portions of the letter p may be constituted by respective elongated elements mounted together in the aperture 18. The element may be formed of glass.

In the aperture 19, there are mounted three rectilinear elements, two of which are indicated by the reference numbers 21 and 22. The elements 21 and 22 may be formed of the same material as is the element 20, have the same transverse profile as does the element 20 and be mounted in the aperture 19 in the same manner as the element 20 is mounted.

A filter 23 of sheet material is mounted on the panel 17 inside the housing 10 to lie between the light-sources 16 and the elements 20, 21 and 22.

The filter is coloured to filter out a part of the light emitted from the lightsources 16 and allow only coloured light to fall on the elements 20, 21 and 22.

This light is transmitted through these elements to the outside of the housing 10 but the brightness of each element is not uniform. A person viewing the front wall 11 from outside the housing sees, within each light-transmitting element, brighter and darker bands extending along the element.

The filter 23 may be supported inside the housing by suitable formations provided on the front wall 11, from which it can readily be removed. Thus, the filter could easily be substituted by a differently coloured filter. The filter 23 may be of one colour only or may comprise portions of different colour. Alternatively, a number of filters may be mounted on the front wall II, these being differently coloured.

The internal surface of the walls of the housing 10 may be adapted to reflect light, to reduce the proportion of light which is absorbed by the walls of the housing. The front wall II may be constituted entirely by the panel 17 or may comprise a frame in which the panel 17 is mounted. The elements 20, 21 and 22 may be integral with other parts of the front wall II. Such an integral front wall may be formed by moulding a plastics material. In this case, parts of the front wall other than those parts which define the letters or other symbols to be displayed would be adapted to prevent the transmission of light, for example by the application of an opaque coating or layer, or be adapted to transmit light less completely than are those parts of the wall which define the symbols.

In a case where the device will be illuminated by natural light, the light-sources 16 and at least the rear wall 12 of the housing may be omitted so that natural light can fall on the rear face of the panel 17. This arrangement may be suitable in a case where the panel 17 is to be installed in an aperture in a door or an aperture in a wall of a building.

The features disclosed in the foregoing description, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (14)

1. CLAIMS:

   I. A mask in which there is incorporated a light-transmitting element, whereby light can pass through the mask by way of said element and wherein the element has a non-uniform thickness.
2. 2. A mask according to Claim I wherein the thickness of the mask is substantially less than the thickness of said element.
3. 3. A mask according to Claim I or Claim 2 wherein said element is elongated and arranged with its length generally transverse to the direction in which light passes through the mask.
4. 4. A mask according to Claim 3 wherein said element has a curved profile, as viewed in cross-section in a plane transverse to its length.
5. 5. A mask according to Claim 3 or Claim 4 wherein said element is tubular.
6. 6. A mask according to any preceding Claim wherein said element is transparent.
7. 7. A mask according to any preceding Claim which incorporates a plurality of light-transmitting elements.
8. 8. A mask according to any preceding Claim comprising a panel defining an aperture which is occupied by the light-transmitting element.
9. 9. An assembly comprising a mask according to any preceding Claim and a light-source for illuminating the or each light-transmitting element from one side of the mask.
10. 10. An assembly according to Claim 9 comprising a housing, wherein the mask forms or is incorporated in a wall of the housing and wherein the lightsource is disposed inside the housing.
11. II. An assembly according to Claim 9 or Claim 10 wherein there is interposed between the light-source and the light-transmitting element a coloured filter.
12. 12. The combination comprising a mask according to any one of Claims I to 8 and a coloured filter.
13. 13. A sign substantially as herein described with reference to the accompanying drawing.
14. 14. Any novel feature or novel combination of features disclosed herein or in the accompanying drawing.