WO1989011713A1

WO1989011713A1 - Luminaire for signs

Info

Publication number: WO1989011713A1
Application number: PCT/AU1989/000223
Authority: WO
Inventors: David Robin Bean; John Brown
Original assignee: STANILITE PACIFIC Ltd
Current assignee: STANILITE PACIFIC Ltd
Priority date: 1988-05-19
Filing date: 1989-05-19
Publication date: 1989-11-30
Anticipated expiration: 1990-11-19

Abstract

An internally illuminated, edge lit sign assembly comprising a source of strip illumination (15), a planar material (12) capable of internally passing light emitted from the source of strip illumination (15), the planar material being of essentially uniform composition throughout and having front (18) and rear (19) planar faces, the planar faces bounded by an edge surface (16, 20, 21, 17), at least a portion of which edge surface is adapted to receive light emitted from the source of strip illumination (15), at least a portion of the light emitted from the source of strip illumination (15) being distributed within the planar material (12). The assembly includes an indicia volume (20) which, in most forms of the invention, comprises a surface roughening of a specified type whereby light rays emanating from the source of strip illumination (15) and incident upon the volume (20) are refracted either forwardly through to the front planar face (18) or rearwardly through to the rear planar face (19). In a particular form of the invention the front face (12) is angled towards the rear face (19) whereby the planar material (12) is a genrally wedge shaped structure. The assembly is particularly suited for special purpose lighting required for exit signs and the like where stringent requirements relating to contrast between lettering and background illumination on a sign must be met.

Description

LUMINAIRE FOR S IGNS

The present invention relates to a luminaire assembly for signs and the like. More particularly the present invention relates to luminaire assemblies for signs and the like which are of the internally illuminated, edge lit type.

PRIOR ART

Prior art "internally illuminated" signs are known. Figures 1 and 2 show two types of such prior art signs. Figure 1 shows the particular variety known as internally illuminated, back lit. In this type of sign, as shown, a light source is located immediately behind an at least semi-transparent sign 2 having relatively opaque indicia 3 marked thereon (or vice versa). The light or lights 4 are arranged to shine through the sheeting thereby resulting in the indicia 3 being clearly visible to an outsider observer by virtue of differences in the transmission of the light from the light sources 4 through the sign backing material 2 and the indicia 3. This form of assembly typically provides the illumination characteri sti cs requi red for emergency si gns and the l i ke as spec i fi ed i n Australian Standard AS 2293.1 (1987), particularly Section 2.5. Such assemblies are, however, relatively bulky.

To overcome the problem of bulkiness referred to above there is also known the internally illuminated, edge lit type of sign as generally illustrated in Figure 2. This type of sign comprises a generally clear sheet of material 5 having a strip light source 6 arranged to shine light through at least one edge surface of the sheet. The sheet 5 has sunken, etched letters 7 engraved into a front face, the cross-section of the etching being more clearly shown in section AA of Figure 2. The light from the light source 6 is refracted through at least the front surface of the sign 5 in such a way that the edges of the lettering 7 tend to exhibit more luminance than other portions of the lettering. Frequently a uniformly coloured backing sheet 8 is provided having stenciled thereon a minic of the indicia 7 whereby, when viewed from the front of the sign 5, the observer can also view light reflected from the indicia on the coloured backing sheet 8. The clear sheet 5 is typically commercially available planar acrylic sheeting or the like, which sheeting has parallel front and rear faces and which sheeting is merely cut to size or equivalent by the sign manufacturer or plastic supplier/manufacturer. The etching of the indicia 7 is subsequently added as an additional manufacturing step", the major area of the sunken surface (generally designated 9) being relatively smooth. This form of internally illuminated, edge lit sign tends to exhibit a non-uniform luminance to the observer when viewed from the front. Typically the luminance is greater near the top of the sign (closest to the light source) and least at the bottom of the sign (furthest from the light source). This variability in luminance is undesirable particularly when the ratio of luminance of the brightest point of the background compared with the darkest point of the background exceeds acceptable limits. Furthermore whilst this form of construction allows considerable contrast at the edges of the lettering 7 as compared with the background luminance the high contrast does not extend uniformly across and within all of the lettering.

Australian Patent Application No. 54158/79 to PLUMLY provides a summary in its introductory portion of the relevant prior art. AUA54158/79 discloses the general idea of roughening a face of a light transmitting planar material, the roughened face being opposite that face of the material through which light is ultimately to be transmitted to viewers. The construction of embodiments of the present invention differ in detail from that disclosed in the PLUMLY citation and also result in an improved illuminated sign arrangement, particularly in the context of exit signs used under emergency conditions and in the context of satisfying AS2293.1 (1987). The text of AUA54158/79 is incorporated herein by cross reference. The text of the United States Patents listed on page 2 of AUA54158/79 is also incorporated herein by cross reference.

Australian Standard AS 2293.1 (1987) is specifically directed at requiring uniform luminance of the lettering, uniform luminance of the background surrounding the lettering (for a predetermined distance around the' lettering) and for ensuring a minimum contrast between the luminance levels of the lettering and of the background.

It is an object of the present invention to provide an internally illuminated, edge lit type of sign which provides improved uniformity of luminance of lettering and of background when compared to prior art internally illuminated, edge lit signs. SUMMARY OF THE INVENTION According to the present invention there is provided an internally illuminated, edge lit sign assembly comprising a source of strip illumination; a planar material capable of internally passing light emitted from said source of strip illumination; said planar material being of essentially uniform composition throughout and having front and rear planar faces; said planar faces bounded by an edge surface at least a portion of which edge surface is adapted to receive light emitted from said source of strip illumination, at least a portion of the light emitted from said source of strip illumination being disbributed within said planar material; said planar material having a refractive index greater than that of the light transmitting medium in which it is immersed; an indicia volume (indicia-shaped in the plane of said planar material) having means entrapped within said volume for refracting or reflecting (or a combination of both) light rays emanating from said source

of strip illumination and incident upon said volume in either or both of a direction forwardly through said front planar face and/or a direction rearwardly through said rear planar face.

Preferably said indicia volume is constituted by the application of a light transmitting material to said rear surface; said light transmitting material having entrapped within it randomly oriented particles; said particles having a refractive index different from said light transmitting material. (In a particular preferred form said particles have a refractive index greater than that of the volume in which they are immersed, which volume itself has a refractive index which is greater than that of said planar material).

In an alternative preferred form said light transmitting material is applied to said from surface instead of said rear surface or in addition to being applied to said rear surface.

In a further alternative preferred form said light transmitting material is located within said planar material.

In yet an alternative preferred form said indicia volume is constituted by finely etched markings being inscribed into said rear surface of said planar material. In yet an alternative preferred form said light transmitting material is effected by "doping" of said rear surface of said planar material in order to achieve an indicia volume with a different refractive index or opaqueness as compared with that of said planar material.

Preferably all external dimensions of said planar material are much greater than the wavelength of light emitted by said source of strip illumination.

Preferably said source of strip illumination is located externally adjacent at least a portion of said edge surface and arranged so that light from said source of strip illumination is directed through said portion of said edge surface and into said planar material substantially in one general direction.

Preferably said external light transmitting medium is air. Preferably said planar material comprises acrylic plastic, clear plastic ploycarbonate, plexiglass and the like.

Preferably said edge surfaces comprise a top edge surface, first and second opposed side edges and a bottom edge.

Preferably said source of strip illumination is externally adjacent to and extends substantially the length of said top edge surface whereby light from said source of strip illumination is directed into said planar material through said top edge surface and substantially in the direction of said bottom edge.

Preferably said front and said rear planar faces are not parallel.

Preferably said front and said rear planar faces taper continuously closer together in the general direction of said light rays. Preferably the angle of said taper is an internal angle in the range 1° - 30°. More preferably the internal angle range is 1° - 5º. Most preferably the angle is approximately 2°.

Preferably said planar material is of width approximately 400mm, height approximately 175mm and has a top edge surface depth of approximately 9mm and a bottom edge depth of approximately 2mm.

Preferably said indicia volume comprises a roughened area inscribed on said rear surface of said planar material which when viewed from said front planar face by an observer located in said light transmitting medium in which said planar material is immersed forms intelligible markings; said roughened area comprising irregularities in said rear surface whereby the directions of internal reflection of said light upon striking said irregularities is randomised resulting in at least portions of said light immediately following so striking irregularities being passed forwardly through said front surface thereby resulting in a relatively higher proportion of said light emerging from said front surface at those locations than would otherwise be the case.

Preferably said sign assembly also includes an opaque planar backing sheet having a first planar face adapted to be placed against or in close juxtaposition with said rear face of said planar material, said first planar face having inscribed thereon uniformly coloured indicia areas of contrasting colour as compared to said uniform background colour, said uniformly coloured indicia areas appearing to an observer as intelligible markings when viewed through said planar material from said front surface of said planar material.

Preferably said uniformly coloured indicia areas are co-extensive with and mirror said roughened area on said rear surface of said planar material when the two are placed against each other or are in close juxtaposition.

In an alternative preferred form said uniformly coloured indicia areas themselves comprise roughened raised surfaces relative to said uniform background colour whereby light refracted out of said rear surface is randomly scattered by said roughened raised surface and at least portions of the randomly scattered light are reflected generally perpendicularly back into said planar material through said rear surface at such an angle that said light continues through said planar material and is immediately refracted out of said front surface of said planar material rather than being internally reflected thereby resulting in increased perceived relative luminance of said indicia when viewed by an observer from said front surface of said planar material.

In a further broad form there is provided an internally illuminated, edge lit sign assembly comprising a source of strip illumination; a planar material capable of internally passing light emitted from said source of strip illumination; said planar material being of essentially uniform composition throughout and having front and rear planar faces; said planar faces bounded by an edge surface at least a portion of which edge surface is adapted to receive light emitted from said source of strip illumination, at least a portion of the light emitted from said source of strip illumination being distributed within said planar material; said planar material having a refractive index greater than that of the light transmitting medium in which it is immersed; said front and said rear planar faces being not parallel, said front and said rear planar faces tapering continuously closer together in the general direction of said light rays.

Preferably the angle of said taper is an internal angle in the range 1º - 30º . More preferably the internal angle range is 1° - 5°. Most preferably the angle is approximately 2°.

In an alternative broad form the essence of the above described invention is utilised, but in "negative" form ie, said indicia volume comprises the bulk of said planar material leaving only unmodified portions of either the rear face, from face or regions sandwiched therebetween appearing as intelligible indicia to an observer viewing said front face of said planar material.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described with reference to the drawings wherein:

Figure 1 discloses a prior art internally illuminated, back lit sign,

Figure 2 discloses a prior art internally illuminated, edge lit sign,

Figure 3 shows diagramatically some of the possible principles of operation of aspects of the present invention,

Figure 4 discloses a first embodiment of the present invention, Figure 5 discloses a second embodiment of the present invention, Figure 6 discloses a third embodiment of the present invention, Figure 7 discloses a fourth embodiment of the present invention, and

Figure 8A shows a perspective view of a fifth embodiment, Figure 8B shows a right side view of a fifth embodiment, Figure 8C shows view of the liminaire housing assembly of the fifth embodiment,

Figure 8D shows a left end view of the clear planar material which forms the facia of the fifth embodiment, Figure 8E shows a right end view of the planar material of the fifth embodiment,

Figure 8F shows a front view of the planar material and a section through the planar material of the fifth embodiment.

Figure 9 discloses alternative light source arrangements relative to the planar material.

Figure 10 discloses an arrangement used for the 6th to 11th embodiments of the invention.

DETATLED DESCRIPTION OF PREFERRED EMBODIMENTS

Figures 1 and 2 have been previously described in the introductory portion of this specification, the luminaire of Figure 2 being an internally illuminated, edge lit type of the same general construction as the preferred embodiments of the present invention. Detailed differences will, however, become clear in the following description of the preferred embodiments of the present invention.

Referring, initially, to Figure 3 there is shown the behaviour of light rays trapped within a medium, which medium has non-parallel boundary surfaces. The angled boundary surfaces mean that the angle of incidence of the internal ray as it strikes consecutive internal boundary surfaces is continually changing thereby allowing for the possibility that, eventually, the angle of incidence will be such that the ray is at least partially refracted through the boundary surface to the external medium rather than being entirely internally reflected from the internal boundary wall. It is hypothesised that this angled boundary wall structure allows for an even, uniform escape of light rays from all portions of the boundary walls of the medium in which the light ray is initially trapped.

Section BB in Figure 3 also shows that, proportionately, the number of light rays emerging from a given area of the medium can be increased by roughening the boundary surface in that area whereby there is an increased likelihood that a ray will strike the roughened surface at a critical angle which allows the light ray to escape from the medium.

Also shown in Figure 3 at section CC is the increased probability of re-reflection of an emergent ray from an external roughened surface 10 whereby a proportionately greater proportion of emergent rays are reflected back into the medium and are immediately refracted out of an opposing boundary wall of the medium 11. The roughened surface 10 is a treated surface which is di stringui shed from the surrounding area 12 in that, when viewed from a distance, the light reflected from the roughened surface represents intelligible indicia to an observer.

FIRST EMBODIMENT Referring now to Figure 4 there is shown a first embodiment of the present invention. Specifically there is shown a luminaire for and including a sign comrpising, essentially, a planar backing sheet 13 having a first face 14. The first face 14 faces a rear face 19 of a planar material 12. The planar material 12 has, in addition to the rear face 19, a front face 18, a top edge 16, a bottom edge 17, a first side edge 20 and a second side edge 21. A source of strip illumination 15 is located generally above the top edge 16 and arranged to inject light rays from the light source into the top edge 16 whereby the light rays enter the interior of the planar material 12. In use the first face 14 of the planar backing sheet 12 is maintained essentially against the rear face 19 of the planar material 12. Intelligible information is communicated to an observer facing the front face 18 of the planar material 12 as follows:

In this particular case the desired information is the word "EXIT". The message is communicated by firstly marking the letters "EXIT" in mirror form as a roughened area on the rear face 19 of the planar material. The roughened surface can be created by any suitable means which provides a finely roughened texture. This can include surface etching (chemical or mechanical), sanding, sand blasting and the like. The important feature in the roughened surface is that it includes variations in the rear surface plane of the rear face 19 which presents a variety of angles of incidence to internally incident light rays whereby an increased proportion of light rays per unit area of incidence strike at angles which cause the incident rays to be at least partially refracted through the rear face and a further proportion of rays per same unit area to be internally reflected in the direction of the front face 18 than would otherwise be the case it the roughening was not there.

Additionally the first face 14 of the planar backing sheet 13 has marked thereon indicia 22 against a uniform background 23. The indicia 22 are coextensive in area with the mirror indicia comprising the roughened area on the rear face 19 of the planar material 12. In this embodiment the indicia 22 comprise white painted letters on a green background 23. The white letters 22 form the word "EXIT" and when the backing sheet 13 is appropriately placed against the rear face 19 of the planar material 12 the white lettering 22 is visible to a viewer viewing through the front face 18, the white lettering being coextensive with the roughened area of the rear face 19 so that It is not obvious to the observer that the lettering is the result of light returning from two planes (the plane of the rear face 19 and the plane of the first face 14).

As shown the cross-section of the planar material 12 parallel to either the first side edge 20 or the second side edge 21 is of right triangular shape. The right triangular cross-section of the planar material 12 combined with the roughened area on the rear face 19 when exposed to light rays injected through the top edge 16 as shown from light source 15 produce an image of the indicia when viewed from the front face 18 which satisfies the requirements of Australian Standard AS 2293, Part 1 (1987), particularly clauses 2.5.2, 2.5.4.1 and 2.5.4.2.

NATA test results carried out on this embodiment which confirm that it satisfies the requirements (in both single sided and double sided form) are attached to this specification as Annexure A.

The text of Australian Standard AS 2293-1 (1987) is incorporated herein by cross-reference.

The double sided version of the first embodiment is simply an assembly incorporating a second planar backing sheet and a second planar material arranged "back to back" against the planar backing sheet 13 and planar material 12 shown in Figure 4. Provided the light source 15 is placed symmetrically across the top of the fitting the single light source can be used to inject light into both planar material components (refer fifth embodiment).

In this first embodiment the sign is of dimensions as shown in Figure 2.3 of page 17 of AS 2293.1 (1987) ie a "24 metre" sign. As stated in the annexed test report the uniformity of luminance and contrast of luminance characteristics required for the exacting task of emergency exit sign lighting were met by this first embodiment.

The planar material of the first embodiment comprises commercially available moulded acrylic material. The backing sheet is formed from cardboard, stiff pager, opaque plastic or the like. The source of strip illumination 15' is a 10 watt "cool white" (4200°K) 26mm diameter tubular fluorescent light tube. Where less exacting requirements are placed on the luminaire for signs ie the lighting uniformity and contrast requirements can be somewhat relaxed as compared with AS 2293-1 (1987) then luminaires can be produced which adopt only some of the features which provide the desired uniformity and contrast.

The second, third and fourth embodiments illustrate exemplary alternative arrangements.

SECOND EMBODIMENT Specifically, referring to Figure 5 there is shown a second embodiment of construction generally similar to that of the first embodiment of Figure 4 save that the right triangular cross-section for the planar material has not bee adopted. Rather the front and rear faces of the planar material are parallel. In this embodiment the roughened texture of the rear surface of the planar material is sufficient to provide an improved uniformly luminant indicia as viewed from the front face of the planar material although not necessarily to the standard of AS 2293-1.

THIRD EMBODIMENT Referring to Figure 6 there is shown a third embodiment where the right triangular cross-section of the planar material is adopted thereby providing uniform luminance across the entire from face of the planar material. However no etching or other surface roughening has been carried out to form indicia on the rear face of the planar material. In this embodiment the indicia applied to the backing sheet 13 form the only means of creating intelligible indicia to a viewer when viewing the assembly from the front face of the planar material 12.

FOURTH EMBODIMENT Referring to Figure 7 a fourth embodiment is shown similar in construction to that of embodiment 3 of Figure 6 save that the indicia 22 on the first base 14 of the backing sheet 13 comprise a raised and roughened surface relative to the background 23 of the first face 14.

The third and fourth embodiments when illuminated as illustrated by the source of strip illumination 15 provide a relatively improved uniform background illuminance behaviour over the whole of the from surface area of the sign although again not necessarily to quite the rigorous standard required by AS 2293-1. FIFTH EMBODIMENT

Referring to Figures 8A and 8F there is shown a fifth embodiment of the present invention, which embodiment is very similar 1n construction to that of the first embodiment save that two portions of planar material have been placed back to back in order to form a double sided sign, the two portions of planar material being anchored within a top housing, which housing also contains the source of strip illumination for the fifth embodiment.

With particular reference to Figures 8D and 8E a specific ridging portion 30 is molded Integrally as part of the planar material, which ridge portion is used to anchor the back to back planar material portions within the slot portion 31 of the strip light source housing 32. The relative dimensions of the embodiment are shown marked on the drawings.

SIXTH EMBODIMENT

The sixth embodiment provides a double sided sign whose lighting characteristics relating to contrast of the message against the background together with evenness and adequacy of background illumination are improved over the first to fifth embodiments described above.

Referring to Figure 10 the sign is shown in diagramatic form and comprises a first planar material 30 of right triangular cross section together with a second planar material 31 also of right triangular cross section, these two components, as shown in Figure 10, noted in opposed relationship with a legend plate 32 interposed therebetween. Onto the rear surfaces 33 and 34 of the planar material 30, 31 is silk screened a UV activated pigment formed into the shape of the desired message (when viewed from the viewing faces 35, 36 of the sign). The legend plate 32. has a legend printed on both sides 37, 38, which legend coincides with the legend silk screened onto the rear faces 33, 34 of the planar materials when the whole assembly is aligned. In use light is projected through top surfaces 39, 40 of the planar material and the sign is viewed from viewing surfaces 35, 36. The use of silk screening results in a particularly fine roughening effect on the surface which results in enhanced apparent brightness of this portion of the sign when viewed from the front viewing direction. The roughening produced by the silk screening process appears to be similar to that achieved by very fine sand blasting. However, such fine sand blasting is very difficult to control in practice. The surface roughening, therefore, in this particular embodiment of the invention is much finer than has been the case typically in the prior art and result in an enhanced illumination performance.

The sixth embodiment can be varied by additionally coating the balance of the rear surfaces 33, 34 with fine droplets of a transparent or translucent green medium thereby giving a "frosted" effect which thereby increased the apparent level of luminence of the background, green areas.

SEVENTH EMBODIMENT This embodiment is essentially as described for the sixth embodiment with reference to Figure 10 except that the rear surface 33, 34 of the planar material (other than that part covered by the legend) is covered with either an applied pigment or very fine etching (either mechanical or chemical etching), thereby providing an alternative means of achieving uniform background illumination.

EIGHTH EMBODIMENT In a further variation of either the sixth or seventh embodiment the legend plate 32 is dispensed with and a plain interleaf substitute.

NINTH EMBODIMENT In a further variation of the sixth and seventh embodiments the legend is applied to the front (viewing) surfaces 35, 36 of the planar material by the same processes as described in embodiments six and seven. The application of the legend to these front faces can be either as an alternative to or in addition to the legend applied to the rear faces 33,

34.

TENTH EMBODIMENT

In a further variation of the sixth, seventh and ninth embodiments the etching of the legend on the rear and/or front surfaces of the planar material is dispensed with entirely and the sign relies entirely upon the legend applied to the faces 37, 38 of the legend plate 32. Naturally the contrast and lighting levels of this embodiment are not as great as those of the others relating to Figure 10. FLEVENTH EMBODIMENT With reference to Figure 10 this embodiment is conceptually the same as that of the sixth, seventh and ninth embodiments save that, in addition, a metal cover plate or an applied opaque coating is applied thereby masking the background field. The lettering can be coloured by means of use of a coloured legend plate or by use of an appropriately coloured opaque or translucent coating on the rear surface or an appropriately coloured translucent coating on the front surface of the two planar material portions 30, 31.

In relation to any of the embodiments of the invention described above a reflective strip can be applied to a lower edge surface of the sign assembly whereby light is reflected back, upwardly into the planar material into which light is initially injected by the light source.

For the purpose of exit signs typical colouring is green lettering on a white (illuminated) background or white lettering on a green background. Naturally other colourings can be used provided that the colouring aids in creating a sufficient contrast level between the lettering and the background for the purpose for which the sign is to be used.

The above describes only some embodiments of the present invention and modifications obvious to those skilled in the art can be made without departing from the scope and spirit of the present invention.

In particular Figure 9 shows some alternative arrangements of light sources relative to the planar material.

ANNEXURE A

NATA TEST SHEETS UPON EMBODIMENTS 1 AND 5

TEST NO. T00541. NATA TEST YES NO

DATE OF TEST: 11-05-88. DATE OF REPORT: 11-05-88.

CLIENT: STANILITE PACIFIC. LTD. ADDRESS: P.O. BOX 182, AUBURN. NSW. 2144 CONTACT : Mr. W. MacDouall . ORDER NO. - - - - - -. LUMINAIRE STANILITE Edge Lit EXIT SIGN Series 2000. Single Sided.

CATALOGUE NO. 2000/110/S.

NATURE OF TESTS: Tested for compliance with the following clauses of

AS2293, Part 1 - 1987 :-

Clauses 2.5.2; 2.5.4.1 and 2.5.4.2.

CLASSIFICATION: Complied in all respects.

NATA REG. NO. 2258.

TESTED BY .........................................................

AUTHORISED SIGNATORY: ...........................................................

DATE: 11.5.88................................................

PAGE 1 OF 4 TEST NO . T00541

DESCRIPTION OF LUMINAIRE

MANUFACTURER: STANILITE PACIFIC LTD. TYPE : Edge Lit EXIT SIGN, Single Sided, Series 2000/110/S.

LAMP : 10 Watt 26mm diam tubular fluorescent, THORN "Coolwhite"

ANCILLIARY EQUIPMENT: Series 7500, 110V, 10W DC, Inverter.

DESCRIPTION OF TEST

TEST PROCEDURES: The test was carried out in accordance with the requirements of AS2293 Part 1 - 1987, "Emergency

Evacuation Lighting In Buildings". Part 1 - Design and Installation, Clause 2.5 EXIT SIGNS.

The test voltage was 88V DC being 80% of the 110V DC central system in accordance with the requirements of Clause A2.4. Test Voltage of AS2293, Part 1.

TEST INSTRUMENT: The equipment used was a TOPCON BM-3 Luminance Meter, SECV Certificate No 87/127.

SIGNED . .. . . . . . .. . . . . . . . . ... . .

PAGE 2 OF 4 TEST NO. T00541.

TEST RESULTS

CLAUSE 2.5.2 DIMENSIONS

The dimensions of the legend complies with the requirements of this clause.

Therefore the sign is suitable for viewing distances up to 24 metres as prescribed in clause 2.5.2.1.

CLAUSE 2.5.4 ILLUMINATION

2.5.4.1. General Requirements.

The sign presents a uniform appearance when viewed from within the range of directions from which it is required to be seen.

UNCERTAINTIES: The uncertainties are not greater than: Applied Voltage ±0.10 volts Luminance + 6.0% of indication + 1% of full range value. Angular measurement ± 0.5 deg.

SIGNED .......................

PAGE 3 OF 4 T00541

TEST RESULTS (cont'd)

CLAUSE 2 .5.4. ILLUMINATION I

2.5.4 .2 Internally illuminated exit signs.

CLAUSE REQUIREMENTS MEASURED ALLOWABLE

2.5.4.2. Minimum (a) (1) Background L, 10.68cd/sq.m. 8 cd/sq.m. within 25mm of legend.

(a) (ii) Ratio of L, 10.60:1 greater than legend to background 4:1

(a) (iii) Variation of L 2.07:1 less than within legend 5:1

Variation of L 1.72:1 less than within background 5:1

SIGNED

PAGE 4 OF 4 TEST NO. T00540. NATA TEST YES NO

DATE OF TEST: 11-05-88, DATE OF REPORT: 11-05-88.

CLIENT: STANILITE PACIFIC. LTD. ADDRESS: P.O. BOX 182, AUBURN. NSW. 2144 CONTACT: Mr. W. MacDouall. ORDER NO. LUMINAIRE STANILITE Edge Lit EXIT SIGN Series 2000. Single Sided.

CATALOGUE NO. 2000/110/S.

NATURE OF TESTS: Tested for compliance with the following clauses of

AS2293, Part 1 - 1987 :-

Clauses 2.5.2; 2.5.4.1 and 2.5.4.2.

CLASSIFICATION: Complied in all respects.

NATA REG. NO. 2258.

TESTED BY

AUTHORISED SIGNATORY:

DATE: .11.5.88.

PAGE 1 OF 4 TEST NO. T00540.

DESCRIPTION OF LUMINAIRE

MANUFACTURER: STANILITE PACIFIC LTD. TYPE : Edge Lit EXIT SIGN, Single Sided, Series 2000/110/D.

LAMP : 10 Watt 26mm diam tubular fluorescent, THORN "Coolwhite"

ANCILLIARY EQUIPMENT: Series 7500, 110V, 10W DC, Inverter.

DESCRIPTION OF TEST

The test voltage was 88V DC being 80% of the 11OV DC central system in accordance with the requirements of Clause A2.4. Test Voltage of AS2293, Part 1.

TEST INSTRUMENT: The equipment used was a TOPCON BM-3 Luminance Meter SECV Certificate No 87/127.

SIGNED

PAGE 2 OF 4 TEST NO . T00540.

TEST RESULTS

CLAUSE 2.5.2 DIMENSIONS

The dimensions of the legend complies with the requirements of this clause.

CLAUSE 2.5.4 ILLUMINATION

2.5.4.1. General Requirements.

UNCERTAINTIES: The uncertainties are not greater than: Applied Voltage ± 0.10 volts Luminance + 6.0% of indication + 1% of full range value Angular measurement + 0.5 deg.

SIGNED

PAGE 3 OF 4 T00540.

TEST RESULTS (cont'd)

CLAUSE 2.5.4. ILLUMINATION 2.5.4.2. Internally illuminated exit signs.

CLAUSE REQUIREMENTS MEASURED ALLOWABLE

(a) (ii) Ratio of L, 10.60:1 greater than legend to background 4:1

(a) (iii) Variation of L 2.07:1 less than within legend 5:1

Variation of L 1.72:1 less than within background 5:1

SIGNED

PAGE 4 OF 4

Claims

1. An internally illuminated, edge lit sign assembly comprising a source of strip illumination; a planar material capable of internally passing light emitted from said source of strip illumination; said planar material being of essentially uniform composition throughout and having front and rear planar faces; said planar faces bounded by an edge surface at least a portion of which edge surface is adapted to receive light emitted from said source of strip illumination, at least a portion of the light emitted from said source of strip illumination being disbributed within said planar material; said planar material having a refractive index greater than that of an external light transmitting medium in which it is immersed; an indicia volume (indicia-shaped in the plane of said planar material) having means entrapped within said volume for refracting or reflecting (or a combination of both) light rays emanating from said source of strip illumination and incident upon said volume in either or both of a direction forwardly through said front planar face and/or a direction rearwardly through said rear planar face.

2. The assembly of claim 1 wherein said indicia volume is constituted by the application of a light transmitting material to said rear surface; said light transmitting material having entrapped within it randomly oriented particles; said particles having a refractive index different from said light transmitting material.

3. The assembly of claim 2 wherein said particles have a refractive index greater than that of the volume in which they are immersed, which volume itself has a refractive index which is greater than that of said planar material.

4. The assembly of any previous claim wherein said light transmitting material is applied to said front surface instead of said rear surface or in addition to being applied to said rear surface.

5. The assembly of claim 2 wherein said light transmitting material is located within said planar material.

6. The assembly of claim 1 wherein said indicia volume is constituted by finely etched markings being inscribed into said rear surface of said planar material.

7. The assembly of claim 1 wherein said light transmitting material is effected by "doping" of said rear surface of said planar material in order to achieve an indicia volume with a different refractive index or opaqueness as compared with that of said planar material.

8. The assembly of any previous claim where all external dimensions of said planar material are much greater than the wavelength of light emitted by said source of strip illumination.

9. The assemble of any previous claim wherein said source of strip illumination is located externally adjacent at least a portion of said edge surface and arranged so that light from said source of strip illumination is directed through said portion of said edge surface and into said planar material substantially in one general direction.

10. The assembly of any previous claim wherein said external light transmitting medium is air.

11. The assembly of any previous claim wherein said planar material comprises acrylic plastic, clear plastic ploycarbonate, plexiglass and the like.

12. The assembly of any previous claim wherein said edge surfaces comprise a top edge surface, first and second opposed side edges and a bottom edge.

13. The assembly of any previous claim wherein said source of strip illumination is externally adjacent to and extends substantially the length of said top edge surface whereby light from said source of strip illumination is directed into said planar material through said top edge surface and substantially in the direction of said bottom edge.

14. The assembly of claim 13 wherein said front and said rear planar faces are not parallel.

15. The assembly of claim 14 wherein said front and said rear planar faces taper continuously closer together in the general direction of said light rays.

15. The assembly of claim 14 wherein the angle of said taper is an internal angle in the range 1° - 30º.

17. The assembly of claim 15 wherein the internal angle range is 1° - 5°.

18. The assembly of claim 15 wherein said internal angle is approximately 2°.

19. The assembly of any one of claims 14 - 18 wherein said planar material is of width approximately 400mm, height approximately 175mm and has a top edge surface depth of approximately 9mm and a bottom edge depth of approximately 2mm.

20. The assembly of any previous claim wherein said indicia volume comprises a roughened area inscribed on said rear surface of said planar material which when viewed from said front planar face by an observer located in said light transmitting medium in which said planar material is immersed forms intelligible markings; said roughened area comprising irregularities in said rear surface whereby the directions of internal reflection of said light upon striking said irregularities is randomised resulting in at least portions of said light immediately following so striking irregularities being passed forwardly through said front surface thereby resulting in a relatively higher proportion of said light emerging from said front surface at those locations than would otherwise be the case.

21. The assembly of claim 20 wherein said sign assembly also includes an opaque planar backing sheet having a first planar face adapted to be placed against or in close juxtaposition with said rear face of said planar material, said first planar face having inscribed thereon uniformly coloured indicia areas of contrasting colour as compared to said uniform background colour, said uniformly coloured indicia areas appearing to an observer as intelligible markings when viewed through said planar material from said front surface of said planar material.

22. The assembly of claim 21 wherein said uniformly coloured indicia areas are co-extensive with and mirror said roughened area on said rear surface of said planar material when the two are placed against each other or are in close juxtaposition.

23. The assembly of claim 21 wherein said uniformly coloured indicia areas themselves comprise roughened raised surfaces relative to said uniform background colour whereby light refracted out of said rear surface is randomly scattered by said roughened raised surface and at least portions of the randomly scattered light are reflected generally perpendicularly back into said planar material through said rear surface at such an angle that said light continues through said planar material and is immediately refracted out of said front surface of said planar material rather than being internally reflected thereby resulting in increased perceived relative luminance of said indicia when viewed by an observer from said front surface of said planar material.

24. The assembly of any previous claim wherein said indicia volume Is created by silk screening a pigment onto an external surface of either or both of said front and rear planar faces.

25. An internally Illuminated, edge lit sign assembly comprising a source of strip illumination; a planar material capable of internally passing light emitted from said source of strip illumination; said planar material being of essentially uniform composition throughout and having front and rear planar faces; said planar faces bounded by an edge surface at least a portion of which edge surface is adapted to receive light emitted from said source of strip illumination, at least a portion of the light emitted from said source of strip illumination being distributed within said planar material; said planar material having a refractive index greater than that of the light transmitting medium in which it is immersed; said front and said rear planar faces being not parallel, said front and said rear planar faces tapering continuously closer together in the general direction of said light rays.

26. The assembly of claim 25 wherein indicia are applied to an external surface of either or both of said front and rear planar faces by silk screening a pigment thereon.

27. The assembly of claim 25 wherein the angle of said taper is an internal angle in the range 1° - 30°.

23. The assembly of claim 25 wherein the internal angle range is 1º - 5°.

29. The assembly of claim 25 wherein the angle is approximately 2°.

30. The assembley of any previous claim wherein the essence of the above described assembly invention is utilised, but in "negative" form ie, said indicia volume comprises the bulk of said planar material leaving only unmodified portions of either the rear face, front face or regions sandwiched therebetween appearing as intelligible indicia to an observer viewing said front face of said planar material.