GB2450090A

GB2450090A - Fascia apparatus for use in a housing with a self-luminous light source

Info

Publication number: GB2450090A
Application number: GB0711143A
Authority: GB
Inventors: Frederick Douglas Williams
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-06-11
Filing date: 2007-06-11
Publication date: 2008-12-17
Also published as: GB0711143D0

Abstract

A fascia apparatus (106) for signage housing employing a self-luminous light source has a multi-layer structure comprising a reflective layer (206) having a light-transmissive region (208) therein for reflecting electromagnetic radiation unable to escape through the light-transmissive region (208) back into a body (104) of a housing (100).

Description

I

FASCIA APPARATUS

1] The present invention relates to a fascia apparatus of the type that, for example, serves as part of a housing for a self-luminous light source.

(0002] In the field of self-luminous signage, it is known to employ tritium gas to manufacture so-called "self-luminous" light sources. In this respect, tritium gas-based light sources have been used for many years and across many industries to make safety signs, patterns and markers, as well as being used in instrument panels. Such self-luminous light sources have also found application in nautical environments, for example shipping, due to the ability of the self-luminous light sources to operate under-water without an external power supply or replacement of any internal power supply. The self-luminous light sources have also been employed in the aerospace industry as well as in difficult terrains, such as deserts, mountains, forests and on off-shore platforms.

(0003] Self-luminous tritium light sources are available in different configurations and sizes, for example cylindrical form with a circular cross-section, tubular form with a square or rectangular cross-section, torroidal form, or spherical form. For all such configurations, at least one surface, or part of a surface to be exposed in at least one direction, is employed as a light-emitting surface.

4] Chemically, tritium gas is an unstable isotope of hydrogen and emits electrons upon decay of the nucleus of the isotope, thus emitting low-energy 3 radiation. Tritium has an approximate half- life of 12.5 years and light sources comprising tritium gas have a useful lifespan of about 25 years.

5] Commercial quantities of tntium gas are available as a by-product of the nuclear fission process used in nuclear power reactors to generate electricity. Due to the tritium gas being a radioactive substance, generation and distribution of the tritium gas is tightly controlled and regulated by governmental agencies in the UK and elsewhere. Furthermore, for use as self-luminous light sources, the level of purity of tritium gas needs to be high, of the order of 99.99% purity levels, but production costs are high to achieve such levels of purity for the tritium gas.

[00061 In this respect, the tritium gas obtained directly as a by-product of the nuclear power generation process has a low purity, the tritium gas by-product containing a number of impurities, for example helium. Water is another impurity and occurs in larger quantities that other impurities in the tritium gas production process, resulting in the creation of tritiated water.

7] The 13 radiation emitted by the tritium gas is known to excite certain phosphors, which are excited by the energy of the 3 radiation into a state that results in the emission of photons. Hence, once purified, the tritium gas is sealed within a borosilicate glass capsule having its internal surface coated with a suitable phosphor. Typically, such self-luminous light sources are encased in a mall black anodised aluminium housing or a high-impact plastic housing to preserve the structural integrity of*the borosilicate glass capsule.

8] Due to the relatively expensive production costs of purified tritium gas, any improvement in the efficiency of the use of the purified tntium gas is desirable from a commercial perspective. Additionally, conservation, of what is a very limited commodity, through efficient use and maximum exploitation of the purified tritium gas is also desirable.

9] Indeed, examples of inefficient use of self-luminous light sources are disclosed in US patent no. US 4,383,382 and UK patent no. GB 1,030,951. In relation to GB 1,030,951, elongate self-luminous light sources are used in a segmented fashion to construct letters and numbers used behind a front panel in signage, for example the capital letter E' being composed from one vertical light source and three, shorter, horizontal light sources. As an alternative, US 4,383,382 discloses the use of a front panel having opaque lettering formed therein and an array of parallel self-luminous light sources disposed behind the front panel and in front of reflectors of varying horizontal widths in order to provide illumination behind lettering of varying widths.

(0010] Alternatively, a single self-luminous light source can span the width of a sign having a rear reflector to direct as much light as possible towards a front panel of the sign containing the opaque lettering as described in US 3,409,770.

However, light output of the sign is low as is uniformity of distribution of luminous intensity.

1] According to a first aspect of the present invention, there is provided a fascia apparatus for a housing for a self-luminous light source, the apparatus comprising: a display panel including: a message layer; and a reflective layer arranged to provide a window to the message layer and, when in use, reflect inwardly electromagnetic radiation that does not pass through the window.

2] The message layer may comprise a message portion transmissive to electromagnetic radiation and an opaque region. The window may comprise another message portion and a reflecting region, the another message portion corresponding to the message region of the message layer.

3] The another message portion of the reflective layer may be of a larger scale than the message portion of the message layer.

4] The message portion may bear a same informational content as the another message portion and expressed in a same manner. The another message layer may be sufficiently large to prevent visibility thereof through the message portion.

5] A reflector unit may be disposed, when in use, behind the reflective layer, the reflector unit having a light-reflecting layer disposed thereupon.

(0016] According to a second aspect of the present invention, there is provided a self-luminous sign apparatus comprising the fascia apparatus as set forth above in relation to the first aspect of the invention.

(0017] The apparatus may further comprise a body defining an open cavity for receiving a self-luminous light source, an internal surface of the body having a light-reflecting layer disposed thereupon.

8] It should be understood that references herein to the self-luminous light source are intended to refer to any light source that provides emissions, electromagnetic or nuclear, to serve ultimately to provide light for illumination purposes. Furthermore, self-luminous light sources do not require an external power supply for generating electromagnetic radiation in the visible range of the electromagnetic spectrum. Rather, the energy is "internally" released for conversion into such electromagnetic energy, i.e. no electrical current needs to flow through a device or component in order to achieve emission of visible light.

9] It is thus possible to provide a reflector apparatus that optimises use of emissions from a self-luminous light source and so results in improved output light intensity levels, which is of particular benefit for signage applications.

0] At least one embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a self-luminous sign unit; and Figure 2 is a schematic diagram of a fascia apparatus constituting an embodiment of the invention.

1] Throughout the following description identical reference numerals will be used to identify like parts.

[00221 Referring to Figure 1, a self-luminous sign unit 100 typically comprises a housing 102 formed from a body 104 that defines an open cavity (not shown) and a front panel, or fascia, 106 that closes the open cavity. The fascia 106 bearing an opaque region 108 surrounding, in this example, a light-transmissive message 110 or pictogram, for example the word "EXIT", or a running man with an arrow pointing to a safe direction of escape.

3] Referring to Figure 2, the fascia 106 is a multi-layer structure comprising a protective cover layer 200. In this example, the cover layer 200 is formed from Polyethylene Thallate Glocol (PETG) or polycarbonate or any other suitable light-transmissive protective material that is, for example, fire-resistant.

4] A message layer 202 is disposed adjacent the cover layer 200, the message layer 202 having the opaque region 108 and a first light-transmissive message and/or pictogram 110. The first light-transmissive message and/or pictogram 110 can be formed as one or more solid light-transmissive regions amongst the opaque region 108, or as one or more cut-outs or apertures in the opaque region 108.

(0025] A diffuser layer 204 is disposed adjacent the message layer 202 and is formed from an etched glass material manufactured by Ritrama, Inc, for example a "PTA Silver" etched glass product available from dorotape (UK) Limited of Market Harborough, Leicestershire, UK, or any other suitable material capable of diffusing, particularly visible light.

(0026] A reflective layer 206 is then disposed adjacent the diffuser layer 204. The reflective layer 206 is, in this example, formed from any suitable reflective material from the acrylic or the vinyl group of polymers, such as polyvinylchloride (PVC). In this example, a back surface 210 relative to the body 104 of the reflective layer is high- gloss and white in colour. Alternatively or additionally, a paint having a light-reflecting pigment, for example, titanium dioxide, can be used to coat the back surface 210 where appropriate.

7] The reflective layer 206 has a second light-transmissive message and/or pictogram 208 formed therein, either as one or more solid light-transmissive (as opposed to reflective) regions formed in the reflective layer 206 or one or more cut-outs or apertures in the reflective layer 206. The second light-transmissive message and/or pictogram 208 are the same message in terms of shape as the first light-transmissive message and/or pictogram 110, but align when the fascia 106 is assembled. However, the scale of the second light-transmissive message and/or pictogram 208 is greater than that of the first light-transmissive message and/or pictogram 110.

8] In this example, the cover layer 200, the message layer 202, the diffuser layer 204 and the reflective layer 206 are sandwiched together and maintained in abutment by an adhesive applied around the periphery of the surfaces of these layers to be held together as a single unit constituting the fascia 106.

9] In this example, one or two layers of light-reflecting, such as white, paint are disposed on the reflector tray (not shown). Additionally, or alternatively, one or two layers of light-reflecting, such as white, paint are disposed on one or more interior surfaces of the body 104. One technique for depositing the layer(s) of paint is by spray-painting.

0] In operation, self-luminous light sources (not shown) are contained within the housing 102 and emit, inter alia, visible light, for example around 560 nm in wavelength. In this example, the self-luminous light sources comprise capsules or cylinders formed from borosilicate glass to contain purified tritium gas, the internal surface of the capsule being coated with a phosphor, for example zinc sulphide.

The skilled person will appreciate that other phosphors or radioactive materials can be employed where appropriate. The self- luminous light sources are disposed in a reflector tray (also not shown) within the body 104 for directing light emitted by the self-luminous light source towards the fascia 106 when placed over the body 102 to form the housing 100. Of course, whilst use of a single self-luminous light source has been described above, the skilled person will appreciate that a greater number of self-luminous light sources can be employed.

1] Light incident upon reflective portions of the reflective layer 206 are reflected back into the housing 102 for "re-use" by reflection of the returned light back towards the fascia 106 by the light-reflecting paint deposited within the body 104 and/or on the opposing surface of the reflector tray. The second light-transmissive message and/or pictogram 208 is sufficiently large to prevent visibility thereof through the message layer 202, whilst optimising reflection of light back into the housing 102, for example by providing a peripheral border of more than about 3 mm, for example for than 5 mm, such as 10 mm.

2] Light that escapes the confines of the body 104 and the reflective layer 206 through the light-transmissive region(s) or aperture(s) in the reflective layer 206 are then incident upon the diffuser layer 204, where the incident light that has escaped is diffused. Consequently, about 85% of the light incident upon the diffuser layer 204 is allowed to propagate to the message layer 202.

3] The diffused light is visible by the naked eye through the light-transmissive regions or apertures of the message layer 202 and the transparent protective cover layer 200. As the size of the second message and/or pictogram 208 is larger than the first message and/or pictogram 110, the boundaries of the second message and/or pictogram 208 are not visible to an observer of the self-luminous sign unit 110.

4] Hence, through use of the reflective layer 206 and/or depositing paint within the body 104, improved light output by the self-luminous sign unit 100 can be achieved.

Claims

Claims: 1. A fascia apparatus for a housing for a self-luminous light

source, the apparatus comprising: a display panel including: a message layer; and a reflective layer arranged to provide a window to the message layer and, when in use, reflect inwardly electromagnetic radiation that does not pass through the window.
2. An apparatus as claimed in Claim 1, wherein the message layer comprises a message portion transmissive to electromagnetic radiation and an opaque region.
3. An apparatus as claimed in Claim 2, wherein the window comprises another message portion and a reflecting region, the another message portion corresponding to the message region of the message layer.
4. An apparatus as claimed in Claim 3, wherein the another message portion of the reflective layer is of a larger scale than the message portion of the message layer.
5. An apparatus as claimed in Claim 3 or Claim 4, wherein the message portion bears a same informational content as the another message portion and expressed in a same manner.
6. An apparatus as claimed in any one of the preceding claims, wherein a reflector unit is disposed, when in use, behind the reflective layer, the reflector unit having a light-reflecting layer disposed thereupon.
7. A self-luminous sign apparatus comprising the fascia apparatus as claimed in any one of the preceding claims.
8. An apparatus as claimed in Claim 7, further comprising a body defining an open cavity for receiving a self-luminous light source, an internal surface of the body having a light-reflecting layer disposed thereupon.
9. A reflector apparatus substantially as hereinbefore described with reference to Figures 1 and 2.