AU665895B2 - Large scale billboard display - Google Patents

Description

1 BACKGROUND OF THE INVENTION The present invention relates generally to ink jet printing systems for large scale graphic generation and deals more particularly with a method for producing a large scale color graphic that presents substantially the same spectral content to a viewer when the graphic is illuminated with front or back lighting.

Large scale color graphic systems for producing images on sheet material or other substrates for use in outdoor advertising, road side billboards and signs and displays in railway or airport terminals, shopping malls and other such public areas are disclosed in U.S. Patent 4,547,786 entitled "INK JET PRINTING SYSTEM" and U.S. Patent 4,811,038 entitled "INK JET PRINTING SYSTEM AND DRUM THEREFORE" both of which are assigned to the same assignee as the present invention and the disclosures of which are incorporated herein by reference.

The large scale color graphic systems, such as those referenced above, produce images using four color process pigment inks on an opaque white substrate. The images are generally optimized for outdoor viewing in natural liSht by da i and may be illuminated from the front by artificial lighting means for viewing at night. Although there is a difference in the spectral content of the viewed image under natural and artificial illumination, the lighting is sufficiently similar to cause the image produced with the four color process pigmented inks to appear substantially the same under either natural or artificial illumination. Additionally, the contrast of the image, that is, the ratio of the light reflected from

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2 the lightest area on the image to the light reflected from the darkest area on the image, remains substantially constant regardless of the illumination type.

In order to achieve a more dramatic nighttime effect, images are produced which are intended for backlight viewing, that is, the light source is located such that the image is located between the light source and a viewer. Generally, these images are produced using four color process pigmented inks deposited on a translucent white substrate. The substrate carrying the image is suspended on a frame or other such apparatus and is illuminated with a light source located at the rear, that is, on the opposite side of the substrate carrying the image.

A general problem associated with images produced on a substrate intended for backlighting is that the image must generally be produced with more highly pigmented inks or thicker ink films than those images produced on substrates intended for lighting by front illumination. When such images are illuminated by backlight at night, the image is of generally good quality however, during daytime viewing, the same image generally appears very dark and the colors may not be true, that is, not having the same spectral content when viewed by a viewer under the different lighting conditions. i( It is ther.2ore a general aim of the present invention to substantially overcome the problems associated with images produced on a substrate and which have different spectral content when illuminated by backlighting and front lighting.

*it o r 3 Summary of the Invention According to a first embodiment of this invention there is provided a large scale billboard display for use with backlighting and frontlighting for displaying a colour image which exhibits substantially an equivalent spectral content when the image is illuminated with either backlight or with frontlight, :rid billboard display being made in accordance with the following steps: applying a first ink film on a first surface; applying a second ink film on a second surface; locating said first and second ink films in registry; front light passing through said first ink film thickness twice from a light source located on the front side as said first surface and back light passing through said second ink film and said first ink film from a light source located on the back side of said first surface whereby light passes through two film thicknesses in either case, whereby a viewer observing said first ink film on the front side as said first ink film observes light having the same spectral content as light passing through said second ink film and said first ink film from a light source located on the back side of said first film.

According to a second embodiment of this invention there is provided a large scale billboard display for use with backlighting and froint!ighting for displaying a colour image using four colour process on a substrate wherein a viewer perceives substantially the same spectral content when the image is illuminated by backlight or frontlight, said billboard display being made in accordance with the steps of: providing at least one sheet-like substrate having front and rear surfaces for receiving or not receiving one or more coloured inks in predetermined amounts in registry to produce a resultant desired colour forming the image; °0 25 depositing one or more coloured inks in predetermined amounts and at predetermined locations on one of said front and rear surfaces to form the image; depositing one or more coloured inks in predetermined amounts and at predetermined locations on the other of said front and rear surfaces, said inks and SS 'predetermined locations on said other of said front and rear surfaces being in registry with 30 said inks and said predetermined locations on said one of said front and rear surfaces whereby the image formed on said one of said front and rear surfaces is the mirror image of the image formed on said other of said front and rear surfaces. i E According to a third embodiment of this invention there is provided a large scale billboard display for use with backlighting and frontlighting for displaying a colour image with four colour process inks on a surface whereby the image exhibits substantially the same spectral content when illuminated by a light source located in front of the surface carrying the image as when illuminated by a light source located behind the surface R1. carrying the image, said billboard display being made in accordance with the steps of: I J [N:\LIBXX](00703:VGS/KEH ~p -y i I- i- 1 I- 3A providing at least one sheet of a material having a front and rear surface for receiving on at least one of said front and rear surfaces, the coloured inks at predetermined locations on the sheet surface and in a predetermined overlapping manner to generate a first image having the desired colours on the sheet material surface; 6 producing a first image having the desired colours by providing a first ink film on a first surface; producing a second image having the desired colours by providing a second ink film on a second surface, and locating said first and second ink films in registry.

According to a fourth embodiment of this invention there is provided a large scale billboard display for use with backlighting and front lighting for displaying a colour image which exhibits substantially an equivalent spectral content when the image is illuminated with either backlight or front light characterised by: a flexible translucent substrate vinyl sheet material having a front surface and a rear surface disposed opposite said front surface and having optical properties such that light impinging on said front surface from a source of illumination located on the same side as said front surface is reflected therefrom and light directed at said rear surface from a source of illumination located on the same side as said rear surface passes therethrough; one or more coloured inks deposited at predetermined locations in a first ink film thickness on said front surface for producing the desired colour image on the front surface; one or more coloured inks deposited at predetermined locations in a second ink film thickness on said rear surface for producing said desired colour image on said rear 1 surface, said one or more coloured inks deposited at predetermined locations on said front surface being disposed substantially opposite said one or more coloured inks deposited at Ot "predetermined locations on said rear surface so that said desired image on said front surface has substantially the same ink film thickness as the ink film thickness of said desired image on said rear surface, said desired image on said front surface being the mirror image of and in registry with said desired image on said rear surface, whereby light from a light source located on the same side as the front surface passes through said first ink film thickness impinging on the front surface and being reflected back through said first ink film thickness and light from a light source located on the same side as the rear surface passes through said second ink film thickness, through 0 said translucent vinyl substrate and through said first ink film thickness such that a viewer located on the same side as the front surface observes light having substantially the same equivalent spectral content when the desired image is illuminated from either a source of 0 backlight or a source of front light.

0000 According to a fifth embodiment of this invention there is provided a large scale billboard display for use with backlighting and frontlighting for displaying a colour image 2; LE [N:\LIBXX]00703:vGS/KEH xcmr 0 4 *l o0 tea~ i oo o oo o oo,0 a i o o oo I o o D a o o which exhibits substantially an equivalent spectral content when the image is illuminated with either backlight or frontlight and characterised by: a flexible substrate having a front surface, one or more coloured inks deposited at predetermined locations in a second ink film thickness on said front surface for producing a desired colour image on said front surface, said first surface being provided with an overpainted layer covering said colour image on said front surface, said overpainted layer comprising a translucent substantially white layer, one or more coloured inks deposited at predetermined locations in a first ink film lo thickness provided on said overpainted substantially white layer for producing a desired colour image thereon, said first ink film thickness providing an image substantially identical to that provided on said first surface and having an ink film thickness of substantially the same thickness as said second coloured ink film forming said above mentioned coloured image, 15 whereby light from a light source located on the same side as said first ink film formed coloured image passes through said first ink film thickness impinging on the substantially white layer and is reflected back through said first ink film thickness, and light from a light source located on the rear side of said substrate passes through said substrate, and through said second ink film thickness and through said overpainted layer and through said first ink film thickness such that a viewer located on the same side of the sign as said first ink film formed colour image observes light having substantially the same or equivalent spectral content.

According to a sixth embodiment of this invention there is provided a large scale billboard display for use with backlighting and frontlighting for displaying a colour image 25 which exhibits substantially an equivalent spectral content when the image is illuminated with eitiier backlight or frontlight and characterised by: a flexible substrate having a front surface, one or more coloured inks deposited at predetermined locations in a second ink film thickness on said front surface for producing a desired colour image on said front surface, a second substrate adjacent said first surface said second substrate covering said colour image on said front surface, said second substrate comprising a translucent substantially white layer, one or more coloured inks deposited at predetermined locations in a first irt.. film thickness provided on said second substrate substantially white layer for producing a desired colour image thereon, said first ink film thickness providing an image substantially identical to that provided on said first surface and having an ink film thickness of substantially the same thickness as said second coloured ink film forming said above mentioned coloured image, I:Yi W 0 C' [N:\LIBXX]00703:VGS/KEH c-- I ~I 3C whereby light from a light source located on the same side as said first ink film formed coloured image passes through said first ink film thickness impinging on the substantially white layer and is reflected back through said first ink film thickness, and light from a light source located on the rear side of said flexible substrate passes through said flexible substrate, and through said second ink film thickness and through said second substrate and through said first ink film thickness such that a viewer located on the same side of the sign as said first ink film formed colour image observes light having substantially the same or equivalent spectral content.

In accordance with the present invention, a method for producing an image with four colour process ink on a substrate surface whereby the image exhibits substantially the same spectral content when illuminated by a light source located in front of the surface carrying the image and when illuminated by a light source located behind the surface carrying the image is presented. One or more of differently pigmented inks are applied or printed onto a surface of a substrate, such as a vinyl flexible sheet which is preferably o 16 translucent, to create the desired coloured graphic. In one aspect of the invention, a second image is created and applied on the opposite surface of the substrate such that the ink film forming the second image is in registry with the ink film forming the first image.

S"When the image is viewed under frontal lighting conditions, light from a light source Spasses through the ink film forming the first image to the substrate and is substantially completely reflected by the substrate surface back through the ink film and toward a viewer. The viewer observes an image illuminated by light that has passed through the ink film an equivalent of two film thicknesses. When the image is illuminated with a backlight, the light from the light source passes through the ink film of the second image, on through the substrate, and through the ink film forming the first image toward a viewer. Again, the viewer observes an image illuminated with light that has passed through two film thicknesses. Accordingly, both front and rear lighting ill.uminate an image that is observed by a viewer wherein the colour content of the light illuminating the image is absorbed and passed by the equivalent of two ink thicknessses with either lighting type and therefore light reaching the [N:\LIBXX]00703:VGS/KEII 1 U- 4 viewer has substantially the same spectral content under either lighting type.

In another aspect of the invention, the second image is created on a surface of a second substrate and both substrates are then laminated such that both images are in registry and alignment with one another. Frontal light passes through the first ink film and is reflected by the surface of the first substrate back toward a viewer such that the viewer observes an image that is illuminated with light which is passed through two ink film thickness. When the image is viewed with backlighting, light passes through the second substrate, which is preferably transparent, through the second ink film and through the first substrate, which is preferably translucent, and through the first ink film in a direction toward a viewer. The viewer observes an image wherein light passes through two ink film thicknesses and has the same spectral content when illuminated by front lighting or backlighting.

,s i S44*4 '4 I cc I; JJ*.4 L I r_ BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the present invention will become readily apparent from the following written description and drawings wherein: Fig. 1 is a vector diagram illustrating cyan, magenta and yellow color components to explain four color process principles.

Fig. 2 shows an ink film on a substrate with front lighting in the prior art; Fig. 3 shows an ink film on a substrate with backlighting in the prior art; Fig. 4 illustrates one embodiment of the method of the present invention wherein a substrate has an ink film on both front and rear surfaces of the substrate; Fig. 5 illustrates another embodiment of the method of the present invention wherein each of two substrates carry an ink film forming the image and are laminated such that the images are in registry; Fig. 6 illustrates another embodiment of the method of the present invention wherein n first ink film image is carried on the substrate surface and is overpainted by a layer of translucent white ink upon which a second ink film image is carried in registry with the first image.

n4- i_ n. m DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Prior to describing the method of the present invention in detail, it is beneficial to have a working knowledge of the four color process system for generating color images of the type with which are of concern to the present invention. Turning first to Fig. 1, a vector diagram is illustrated therein wherein red, blue and green vectors, designated 10, 12 and 14, respectively and vectors 16, 18 and 19 represent the colors yellow, magenta and cyan, respectively.

As known, the red, green and blue vectors represent primary colors and if combined in roughly equal proportions, that is, each vector is substantially the same magnitude, the resultant combination is representative of white light. It can also be seen that if one or more of the red, green, blue vectors have unequal magnitudes with respect to one another, the resulting combination will produce a colored light. The resultant color of any combination of the red, green and blue vectors is determined by the addition of the respective vectors. For example, if the blue vector 12 is removed from white light, only the red and green vectors 10,14 respectively remain and the vector sum of the red and green vectors produce the color yellow shown by the vector 16. If the vector 14, repre- ;sentative of green light, is reduced in magnitude, the '.4o resultant vector will shift clockwise toward the red vector and the resultant color may be seen as orange. Similarly, if the red vector 10 is removed from white light the remaining blue and green vectors 12,14 respectively will produce the color cyan shown by the vector 19. Likewise, if the color green shown as the vector 14 is removed from white light, the remaining red and blue vectors add to produce the color magenta shown by the vector 18.

64i9 4,I« lA I 1 1111111, ssaalllRww i r j7 The foregoing provides the fundamentals for understanding a four color process using transparent substractive pigmented inks to produce a colored graphic image.

For purposes of explanation it is assumed that the various pigmented inks used are ideal. A perfect process yellow ink passes red and green light unattenuated and totally absorbs blue light. Likewise, an ideal perfect process magenta ink is transparent to red and blue light but absorbs green light and an ideal process cyan ink is transparent to blue and green light but absorbs red light. Colored graphic images generated with pigmented inks such as the graphic generation disclosed in the above-identified patents, result in multi-layer ink films and produce accumulative effects. For example, in a two-layer ink film comprised of yellow and magenta process inks, both blue and green light are absorbed and the resultant color is red. In the case of a three-layer ink film of yellow, magenta and cyan, all of the red, green and blue light is absorbed and the resultant color produced is black. For further details of four color process systems and techniques, the reader may refer to numerous textbooks and literature available in the art.

Turning to Figs. 2 and 3, Fig. 2 shows an ink film on a substrate with front lighting in the prior art and Fig. 3 *4 shows an ink film on a substrate with backlighting in the prior art. In Fig. 2, an opaque white substrate generally designated has a front surface 22 and rear surface 24 and upon which an ink film generally designated 26 is applied to the surface 22.

The ink film 26, for purposes of explanation, is considered to be a yellow pigmented ink. The pigmentation of the yellow ink St film 26 is such that 50% of the blue light is removed or ,I .absorbed in a single passage of light through the film. A light source generally designated 28 is assumed to emit white So,, light, which recalling from above, comprises the vector addition of equal magnitude red, green and blue vectors and which white light is shown as the ray 30. The white light ray r r pr C c impinges on the surface 22 of the substrate 20 and is reflected as white light represented by the reflected ray 32.

White light emitted from the light source 28 and designated by the ray 34 passes through the yellow ink film 26 and impinges on the surface 22 of the substrate 20 and is reflected back through the film 26 as reflected ray 36. The yellow ink film absorbs 50% of the blue component comprising the white light ray 34 in one passage through the film toward the substrate surface 22 and passes 100% of the red and green components of the white light. The impinging resultant light is reflected from The substrate surface 22 back through the yellow ink film 26 as reflective ray 36 which comprises 100% of the red and green components and 50% of the blue component reflected from substrate surface 22, that is, the blue component is again reduced by 1/2. An observer indicated generally at 38, views the color of the reflected ray 36 produced by 100% of the red and greel components of the original white light and 25% of the blue component of the original white light. The ink film will appear to the observer 38 as a modestly dense yellow color.

Turning to Fig. 3, an example of a backlit image in the prior art is illustrated wherein the substrate generally c.dsignated 4e is preferably a translucent white substrate and includes a front surface 42 and rear suriAce 44. As in the case of the front light example illustrated in Fig. 2, the ink film is assumed to be a yellow pigmented ink and is generally designated 46 and is applied to the surface 42 of the substrate A white light source generally designated 48 is located behind the substrate 40, that is, on the same side as the rear surface 44 of the substrate 40. For purposes of comparison to o";o the front light example shown in Fig. 2, the intensity of the white light emitted from the light source 48 is made so that o the light represented by the ray 50 passing through the substrate 40 is equal in intensity to the white light rry 32 of Figure 2. This condition is imposed only for purposes of i p__I1~ li~sPI i comparison to the example illustrated in Fig. 2 however, it is i not necessary since the light passing through the ink film 46 and the substrate 40 is judged only with reference to the light passing through the substrate alone. The light emitted from the light source 48 and designated by the ray 52 passes through the substrate 40 and the ink film 46 and emerges as the ray 54.

Since the lIght passes through the ink film 46 only once, the blue component of the white light has a 50% absorption and the light reaching an observer generally designated 56, is comprised of 100% of the red and green components and 50% of the blue component so that the yellow ink film appears to the observer 56 as a pale yellow color.

In order to make the ink film 46 of Fig. 3 look Ssimilar to the color of the ink film 26 in Figure 2, the Sthickness of the ink film in Figure 3 is doubled as is i currently done in the prior art. Since the blue light loss is j 50% for each thickness, the resultant would be light made of 100% of the red and green components and 25% of the blue component thereby appearing as the same color to the respective observers in Figures 2 and 3 when viewed in front and back light, respectively. However, if the substrate and ink film S• Ii Simage of Figure 3 is viewed with a front light source as in the case of Figure 2, the light passing through the double thickness ink film in reality makes four passages through the ink film and the resultant reflected light seen by the observer is comprised of 100% of the red and green components and 6.25% of the blue component. Thus it can be seen that the spectral content of the light reaching a viewer is not the same for both type lighting for each of the images produced in the prior art.

It will be appreciated by those skilled in the art that the above analysis may be extended to ink films of any color or in combinations of any such ink films. The analysis is however, complicated in that the available pigmented inks are not perfect and ideal as assumed in the analysis In Figures l* t, c I A p.C~-XC 81~8RP lsl ~assslrPIPU~WYRbR~B~sllDe~lp~ 2 and 3. Non-linearities in apparent color contamination with film thickness may cause the color of an ink film to be different whether viewed in front or rear light and accordingly, such images produced with conventional known methods do not appear the same to an observer when the image is illuminated with both front and back light even when produced according to the prior art.

Now considering the invention in further detail, reference is made to Figure 4 wherein a substrate, generally designated 58, includes a front surface 60 and rear surface 62.

An image comprised of ink films generally designated as 64 and 66 respectively are applied side-by-side to one surface 60 of the substrate 58. A substantially identical image comprising ink films 68 and 70 respectively are applied to the rear surface 62 of the substrate 58 and in registry with the image applied to the front surface 60. That is, the ink film 68 is in registry with the ink film 64 and the ink film 70 is in registry with the ink film 66. It will be seen that the respective images are mirror images of one another.

A light source generally designated 72 provides front illumination and transmits a ray of white light generally designated 74 toward the substrate 58. The ray 74 passes through the ink film 64 and is reflected by the surface 60 of the substrate 58 back through the ink film 64 as ray 76 toward an observer generally designated 78. The observer sees an image having a spectral content that is the result of light passing through the equivalent of two ink film thicknesses.

When the image is iituminated with a backlight generally designated 80, white light emitted as the ray 82 passes through Sol the ink film 70, through the substrate 58 and through the ink film 66 and emerges as the ray 84 in a direction toward an S* observer generally designated 86. The observer 86 sees a image having a spectral content produced by white light passing through two ink film thicknesses. It can be seen that the 11 observer 78 and observer 86 view an image having substantially the same spectral content whether the image is illuminated by the front light source 72 or the rear light source 88.

In practice, it is preferable that the translucent substrate 58 have an approximate 15% transmission factor resulting in approximately 85% reflectance of light impinging on the substrate surface. It is also found that since imperfect pigmented inks are used and applied to a substrate which is only semi-opaque, and further that the spectral content of the front and back light sources may differ, the optimum reproduction between front and back light conditions may require that the density and color balance of the image applied to the rear surface 62 of the substrate 58 be somewhat different than the density and color balance of the image applied to the front surface 60 of the substrate 58. For example, it may not be necessary to use black pigmented ink on one of the front surface 60 or rear surface 62 which is due in part to the fact that black pigmented ink is nearly opaque and therefore there is no requirement to apply the black pigmented ink to both the front and rear surfaces since all light is substantially absorbed by one thickness.

Turning now to Fig. 5, another embodiment of the method of the present invention is illustrated therein wherein the image to be viewed is created by depositing ink film generally designated 88 on the surface 90 of a substrate 0 generally designated 92. A second image is created by depositing an ink film generally designated 94 on the front surface 96 of a secord substrate generally designated 98. The images carried by the substrates 92 and 98 respectively are l ocated in registry and the substrate 92 and 98 are laminated such that the front darface 96 of the substrate 98 is facing the rear surface 100 of the substrate 92. Preferably, the i substrate 92 has a 15% transmission factor and the substrate 96 is preferably transparent. It will be seen that when the r-

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v 12 substrates are laminated with the ink films and accordingly the images in registry, light originating from a front light source passes through the ink film 88 and is reflected from the surface 90 so that the light passes through two ink film thicknesses. Likewise, light emitted from a backlight passes through the substrate 96, ink film 94, substrate 92 and ink film 88 so that light again passes through two ink film thicknescss. Accordingly, it is seen from Fig. 5 that the method of the present invention provides an image viewed by an observer wherein light reaching the observer has substantially the same spectral content regardless of the image being illuminated by a front light or a back light source.

Turning now to Fig. 6, another embodiment of the method of the present invention is illustrated wherein the desired image is created by a first ink film generally designated 102 which is applied to the front surface 104 of a substrate generally designated 106. The layer of ink film 102 and substrate surface is overpainted with a translucent white paint layer generally designated 108. A second ink film generally designated 110 is applied to the surface 112 of the translucent white ink or paint layer 108 and in registry with the first ink film layer 102. The substrate 106 preferably is e. transparent having a 1001 transmission factor while the layer of translucent white paint or transparent semi-reflective material 108 has a 15t transmission factor. In this embodiment it can be seen from Fig. 6 that light emitted from a light source placed in front of the image passes through the ink film layer 110 and is reflected by the surface 112 of the white ink layer 108 back through the film 110 thereby passing through the ink film twic,., which is the equivalent of two ink thicknesses.

S" Likewise, it can be seen that a light source placed in back of the substrate 106 emits light which passes through the P substrate 106 and through the film 102, through the whice ink layei 108 and through the ink film 110. Accordingly, a viewer r I-

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rr 13 observing the image receives light which has substantially the same spectral content whether the image is illuminated by front light or a back light since the emitted light passes through two thicknesses of ink film in both instances. One benefit of this embodiment is that only one substrate is required thus reducing costs of a final colored graphic that is to be viewed under both front and back lighting conditions.

Again as described above, compensation may be made to correct for imperfect pigmented inks and light sources having different spectral content (such as sunlight and fluorescent lamps) to adjust the density and color balance achieved wiln fronc and back lighting.

A method for producing an image with a four color process ink on a substrate surface wherein the image exhibits i substantially the same spectral content, when illuminated by a i; light source located in front of the surface carrying the image as when illuminated by a light source located behind the surface carrying the image has been disclosed above in several preferred embodiments. It will be understood that additional changes and embodiments may be made by those skilled in the art without departing from the spirit and scope of the present invention. Therefore, the invention has been described by way of illustration rather than limitation.

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Claims (15)

1. A large scale billboard display for use with backlighting and frontlighting for displaying a colour image which exhibits substantially an equivalent spectral content when the image is illuminated with either backlight or with frontlight, said billboard display being made in accordance with the following steps: applying a first ink film on a first surface; applying a second ink film on a second surface; locating said first and second ink films in registry; front light passing through said first ink film thickness twice from a light source located on the front side as said first surface and back light passing through said second ink film and said first ink film from a light source located on the back side of said first surface whereby light passes through two film thicknesses in either case, whereby a viewer observing said first ink film on the front side as said first ink film observes light having the same spectral content as light passing through said second ink film and said first ink film from a light source located on the back side of said first film.

2. The large scale billboard display according to claim 1 wherein the method steps of applying first and second ink films further include the steps of applying said first ink film on a first surface of a first substrate and applying said second ink film on a surface of a second substrate.

3. The large scale billboard display of claim 1 wherein the method steps of applying first and second ink films further include the steps of applying said first ink film on a first surface of a first substrate and applying said second ink film on a second surface of said first substrate and oppositely disposed from said first surface.

4, The large scale billboard display of claim 3 wherein the method steps of applyin, said first and second ink films further include .pplying said first and second ink films to said first and second surfaces respectively of a translucent substrate.

5. A large scale billboard display for use with backlighting and frontlighting for displaying a colour image using four colour process inks on a substrate wherein a viewer perceives substantially the same spectral content when the image is illuminated by 30 backlight or frontlight, said billboard display being made in accordance with the steps of: providing at least one sheet-like substrate having front and rear surfaces for receiving or not receiving one or more coloured inks in predetermined amounts in registry to produce a resultant desired colour forming the image; depositing one or more coloured inks in predetermined amounts and at predetermined locations on one of said front and rear surfaces to form the image; depositing one or more coloured inks in predetermined amounts and at predetermined locations on the other of said front and rear surfaces, said inks and Spredetermined locations on said other of said front and rear surfaces being in registry with Ssaid inks and said predetermined locations on said one of said front and rear surfaces [N,\LIBXX]00703:VGSIKLH oa oo 0* o so o°* 0 o o so oo to er *0 0 000 0440~ 0lr rI. 00,0* II bb----L whereby the image formed on said one of said front and rear surfaces is the mirror image of the image formed on said other of said front and rear surfaces.

6. A large scale billboard display as defined in claim 5 wherein said method step of providing a sheet like substrate includes providing a translucent substrate.

7. A large scale billboard display as defined in claim 5 wherein said step of providing a sheet like substrate includes providing a vinyl translucent substrate.

8. A large scale billboard display for use with backlighting and frontlighting for displaying a colour image with four colour process inks on a surface whereby the image exhibits substantially the same spectral content when illuminated by a light .,Ource located in front of the surface carrying the image as when illuminated by a light source located behind the surface carrying the image, said billboard display being made in accordance with the steps of: providing at least one sheet of a material having a front and rear surface for receiving on at least one of said front and rear surfaces, the coloured inks at predetermined locations on the sheet surface and in a predetermined overlapping manner to generate a first image having the desired colours on the sheet material surface; producing a first image having the desired colours by providing a first ink film on a first surface; producing a second image having the desired colours by providing a second ink film on a second surface, and locating said first and second ink films in registry.

9. A large scale billboard display as defined in claim 8 further including the step of producing said first surface by overpainting said second ink film on said second surface with a white translucent ink film layer.

10. A large scale billboard display as defined in claim 9 further including the step °of illuminating said first ink film by locating a light source on the same side as said sheet 1 material rear surface whereby light passes through said sheet material and said second ink film, through said white translucent ink layer and through said first ink film so that light S, reaching an observer passes through two ink film thicknesses. 3

11. A large scale billboard display as defined in claim 9 further including the step of illuminating said first ink by locating a light source on the same side as said sheet material front surface whereby light passes through said first ink film in one direction toward said white translucent ink layer, and reflecting light impinging on said white t translucent ink layer back through said first ink film in a direction substantially opposite to the one direction so that light reaching an observer passes through two ink film thicknesses.

12. A large scale billboard display for use with backlighting and front lighting for T; displaying a colour image which exhibits substantially an equivalent spectral content when X' the image is illuminated with either backlight or front light characterised by: [N:\LIBXX]00703:VGSIKEH 16 a flexible translucent substrate vinyl sheet material having a front surface and a rear surface disposed opposite said front surface and having optical properties such that light impinging on said front surface from a source of illumination located on the same side as said front surface is reflected therefrom and light directed at said rear surface from a source of illumination located on the same side as said rear surface passes therethrough; one or more coloured inks deposited at predetermined locations in a first ink film thickness on said front surface for producing the desired colour image on the front surface; one or more coloured inks deposited at predetermined locations in a second ink film thickness on said rear surface for producing said desired colour image on said rear surface, said one or more coloured inks deposited at predetermined locations on said front surface being disposed substantially opposite said one or more coloured inks deposited at predetermined locations on said rear surface so that said desired image on said front surface has substantially the same ink film thickness as the ink film thickness of said desired image on said rear surface, said desired image on said front surface being the mirror image of and in registry with said desired image on said rear surface, whereby light from a light source located on the same side as the front surface passes through said first ink film thickness impinging on the front surface and being reflected back through said first ink film thickness and light from a light source located on the same side as the rear surface passes through said second ink film thickness, through said translucent vinyl substrate and through said first ink film thickness such thai a viewer located on the same side as the front surface observes light having substantially the same equivalent spectral content when the desired image is illuminated from either a source of backlight or a source of front light.

13. A large scale billboard display for use with backlighting and frontlighting for "displaying a colour image which exhibits substantially an equivalent spectral content when *the image is illuminated with either backlight or frontlight and characterised by: a flexible substrate having a front surface, one or more coloured inks deposited at predetermined locations in a second 30 ink film thickness on said front surface for producing a desired colour image on said front surface, said first surface being provided with an overpainted layer covering said colour image on said front surface, said overpainted layer comprising a translucent substantially white layer, one or more coloured inks deposited at predetermined locations in a first ink film thickness provided on said overpainted substantially white layer for producing a desired colour image thereon, .said first ink film thickness providing an image substantially identical to that y provided on said first surface and having an ink film thickness of substantially the same [N-,LIBXX]00703:VGS/KEH I Pr- 1 thickness as said second coloured inkk film forming said above mentioned coloured image, whereby light from a light source located on the same side as said first ink film formed coloured image passes through said first ink film thickness impinging on the substantially white layer and is reflected back through said first ink film thickness, and light from a light source located on the rear side of said substrate passes through said substrate, and through said second ink film thickness and through said overpainted layer and through said first ink film thickness such that a viewer located on the same side of the sign as said first ink film formed colour image observes light having substantially the same or equivalent spectral content.

14. A large scale billboard display for use with backlighting and frontlighting for displaying a colour image which exhibits substantially an equivalent spectral content when equivalent spectral content. the image is illuminated with either backlight or frontlight and characterised by: a flexible substrate having a front surface, i O o o n e o r m o r e c o lo u r e d in k s d e p o s ite d a t p r e d e te r m in e d l o c a t io n s in a s e c o n d S 15 ink film thickness on said front surface for producing a desired colour image on said front o 0 0 surface a second substrate adjacent said first surface said second substrate covering 0 said colour image on said front surface, o osaid second substrate com prising a translucent substantially w hite layer, one or more coloured inks deposited at predetermined locations in a first ink film thickness provided on said second substrate substantially white layer for producing a oo o desired colour image thereon, said first ink film thickness providing an image substantially identical to that provided on said first surface and having an ink film thickness of substantially the same thickness as said second coloured ink film forming said above mentioned coloured image. whereby light from a light source located on the same side as said first ink film formed coloured image passes through said first ink film thickness impinging on the substantially white layer and is reflected back through said first ink film thickness, and light from a light source located on the rear side of said flexible substrate passes through said flexible substrate, and through said second ink film thickness and through said second substrate and through said first ink film thickness such that a viewer located on the same side of the sign as said first ink film formed colour image observes light having substantially the same or equivalent spectral content.

15. A large scale billboard display substantially as herein described with reference *same or equivalent spectra! content. to any one of Figures 4-6. NIX 3G" /E N:\LIBXX00703:VGS/MEI II..,A F" 18 Dated 13 February, 1995 Metromedia Company Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON 0* 0 0 a pa 0 0 0 043* 0.4 0 0 2* 0 0 0 0 0 0 0 0000 *0 a. a, a *a ala. a aaaaa a a ~5~9a K [N:\LIBXX]00703:VGS/KEH LARGE SCALE BILLBOARD DISPLAY ABSTRACT A large scale billboard display (58) for use with backlighting (82) and front lighting (74) for displaying a color image which exhibits substantially an equivalent spectral content when the image is illuminated with either backlight (82) or front light (74). 6 Display (58) comprises a flexible translucent substrate vinyl sheet material (58) having a front surface and a rear surface (62) disposed opposite said front surface (60) and having optical properties such that light (74) impinging on said front surface (60) from a source of illumination (72) located on the same side as said front surface (60) is reflected therefrom (76) and light (82) directed at said rear surface (62) from a source of illumination located on the same side as said rear surface (62) passes therethrough; one or more colored inks (64) and (66) deposited at predetermined locations in a first ink film thickness on said front surface (60) for producing the desired color image Son the front surface Sas one or more coiored inks (68) and (70) deposited at predetermined locations in a second ink film thickness on said rear surface (62) for producing said desired color image on said rear surface (62) said one or more colored inks (64) and (66) deposited at predetermined locations on said front surface (60) being disposed substantially opposite said one or more colored inks (68) and (70) deposited at predetermined locations on said rear surface (62) so that said desired image on said front surface (60) has substantially the sarne ink film thickness as the ink film thickness of said desired image on said rear surface said desired image on said front surface (60) being the mirror image of and in registry with said desired image on said rear surface (62), whereby light (74) from a light source (72) located on the same side as the front surface (60) passes through said first ink film thickness impinging on the front surface and being reflected back through said first ink film thickness and light (82) from a light source (80) located on the same side as the rear surface (62) passes through said i second ink film thickness, through said translucent vinyl substrate (60) and through said first ink film thickness such that a viewer (78) or (86) located on the same side as the front surface (60) observes light (76) or (84) having substantially the same equivalent spectral content when the desired image is illuminated from either a source of backlight or a source of front light (72). Figure 4 In:\libxxl00439:pag II II