Image Display System
This invention relates to an image display system.
Advertising hoardings are known which comprise a two dimensional image which is printed onto paper and adhered to the hoarding. Lights may be provided for illuminating the image at night. Another known type of hoarding comprises a backlit transparency carrying a two dimensional image.
Whilst it is expensive to advertise on hoardings, the revenue obtainable by advertising companies from each hoarding is limited. In order to reduce the cost of the hoarding to the advertiser and to increase revenue for the advertising company, it has been proposed to provide various forms of display systems which mechanically change the display image at regular intervals. In this manner, several advertisements are sequentially displayed on the hoarding and thus although the cost to each advertiser is less, the advertising company can obtain an increased revenue.
Another advantage of display systems which sequentially display advertisements in that they are more eye-catching than conventional static advertisements. Hitherto display systems which sequentially display different images have been complicated and expensive in construction.
US Patent No. US 5 962 109 discloses a display system comprising a translucent back film carrying a first image to be displayed, an intermediate diffuser film disposed in front of the first image, and an apertured front film carrying a second image to be displayed. In use, the system is arranged to display the first image when the light intensity behind the rear film is greater -than the light intensity in front of the front film, and to display the second image when the relative light intensities are reversed. The system can thus display either the first image or the second image, depending on the relative light intensities.
The apertured film is of the type disclosed in US
Patent Nos. 4 673 609, 4 925 905, 4 883 556 and 5 525 177 and comprises an opaque sheet of flexible plastics film, in which an of apertures is formed. The image is printed on the front surface of the film. In use, when the level of light behind the rear film is greater than that in front of the apertured front film, the first image is visible through the apertures in the front film. However, I have found that the apertured front film is visible and interferes with the presented image. Also, when the level of light in front of the apertured front film is greater than that behind the rear film, the second image formed on the front of the apertured front film is visible. However, the pattern of apertures remains visible and detracts from the presented image. This problem is exacerbated because the intermediate diffuser film, which is normally white in colour so that it does not affect the colour of the first image, is visible as a pattern of white dots through the apertured front film.
Another disadvantage of the apertured film which is used is that it is expensive to manufacture and is only available in small widths, thereby making it unsuitable for use in large advertising hoardings.
I have now devised a display image of the type disclosed in US Patent No. US 5 962 109 which alleviates the above-mentioned problems.
In accordance with this invention there is provided a display system comprising a translucent substrate having a
■translucent image of a first image to be displayed provided on or behind the rear surface thereof and a layer of apertured sheet material disposed in front of said substrate and provided with a second image to be displayed on the front surface thereof, the system being arranged to display said first image when the light intensity behind said substrate is greater than the light intensity in front of said apertured sheet material and to display said second image when the relative light
intensities are reversed, wherein the front surface of the apertured sheet material on which said second image is provided is 3-dimensional .
I have found that both the first and second images are substantially improved by providing the second image on 3- dimensional surface to the apertured sheet material.
The first image is improved because the surface of the apertured sheet material, through which the first image is viewed is 3-dimensional rather than flat and this helps to distract the viewer's eye from the presence of the apertures. Another reason is that the apertured sheet material is less visible because any light incident on the front surface of the apertured sheet material is scattered and is not reflected into the viewer's eye. The second image is improved because the surface of the apertured sheet material on which the second image is viewed is 3-dimensional rather than flat and this helps to distract the viewer's eye from the presence of the apertures. Another reason that the apertures are less visible is that the 3- dimensional surface of the apertured sheet material confines the angles through which light can pass through the apertures. Thus, less light passes through the apertures to illuminate the diffuser film and less of the reflected light passes back through the apertures. In this manner, the level of the white light passing through the apertures is substantially reduced.
The reduction in the amount of light allowed to pass through the apertures also has the effect of darkening the
• first image when the level of light behind the substrate is greater than that in front of the apertured sheet. This has the effect of sharpening the first image and improves the pale and washed out look of the first image provided in the above- mentioned system.
Grids and meshes having a 3-dimensional front surface are widely available in large widths and thus a display system in .accordance with this invention, is less expensive in
construction than the above-mentioned system and can be formed to provide very wide images.
In one embodiment, the apertured sheet material comprises woven or knitted threads, preferably having an irregular pattern of threads and apertures to further help distract the eye from the presence of the apertures.
In an alternative embodiment, the sheet material comprises a punched sheet of material.
Preferably, the apertured sheet material is formed of plastics or of another material such as metal coated with plastics.
Preferably the apertured sheet material comprises an outer layer of PVC: PVC is a plastics material which can accept printing. Preferably, the rear surface of the apertured sheet material on which said second image is provided is 3- dimensional. This further confines the angles through which light can pass through the apertures.
Preferably the first image is printed or otherwise provided on the rear surface of the substrate as a mirror image of the image to be displayed. In this manner, only two sheets are required compared with the three that are required in the above-mentioned system.
The rear surface of the sheet material may be coated with a black material' in order to improve its opacity, e.g. by printing.
The rear surface of the sheet material may abut the
■ front surface of the substrate and indeed, the sheet material may in fact be bonded to the front of the substrate. Preferably, means are provided for back lighting the substrate, in order to display the first image. At night, the substrate may be back lit to display the first image and during day the back light can be extinguished in order to display the second image. Preferably light sensing means are provided for
energising said back lighting means when the light intensity in front of said apertured sheet material falls below a predetermined limit.
Preferably the translucent substrate and the apertured sheet material, carrying the first and second images respectively, are fastened together so as to make it easier to change both images together.
An embodiment of this invention will now be described by way of an example only and with reference to the accompanying drawings in which:
Figure 1 is in a perspective view of an embodiment of display system in accordance with this invention;
Figure 2 is a sectional view along the line II - II of Figure 1; Figure 3 is a front view of the system of Figure 1, when displaying a first image; and
Figure 4 is a front view of the system of Figure 1, when displaying a second image.
Referring to Figure 1 of the drawings, there is shown a display system comprising a housing 10 having a large rectangular opening 11 in its front, through which the images to be displayed can be viewed.
Referring to Figure 2 of the drawings, a plurality of elongate lighting tubes 12 are mounted at the rear of the housing against the back wall thereof. A flat substrate 13 of white paper or plastics material extends across the housing 10 in a plane which extends parallel to the plane of the opening
•11. A mirror image of a first image A to be displayed is printed on the rear of the substrate 13 in the conventional manner.
A mesh 14 of woven or knitted PVC-coated polyester fibres extends across the housing 10 in front of the substrate
13 and in a plane which extends parallel thereto. The 3- dimensional curved front surface of the fibres in the mesh 14 are printed with a second image B to be displayed. The 3-
dimensional curved rear surface of the fibres in the mesh 14 are then printed with a layer of black material 15, in order to improve the opacity of the sheet. However, this is not necessary if the material from which the sheet is formed is sufficiently opaque. The apertures 16 in the mesh 14 preferably occupy approximately 50% of the surface area of the mesh 14.
Referring to Figure 3 of the drawings, in use when the lamps 12 are illuminated and the ambient lighting level is relatively low, light from the lamps 12 is transmitted through the substrate 13 carrying the image A. The coloured areas of the image A filter the light so that the image A becomes visible on the substrate 13.
The light then passes through the apertures 16 in the mesh 14, so that the image A can be seen through the opening 11.
The image B on the mesh 14 cannot be seen be virtue of the fact that the light transmitted through the apertures 16 from behind the image A is brighter than the ambient lighting in front of the system. Furthermore, this factor also helps to make the apertured sheet 14 itself invisible, especially when the display is viewed from a distance.
The 3-dimensional surface of the mesh 14, through which the first image is viewed distracts the viewer' s eye from the presence of the apertures 16. Another reason that the mesh 14 is invisible is that any light incident on the front surface of the mesh 14 is scattered and is not reflected into the viewer' s eye .
Referring to Figure 4 of the drawings, in use when the lamps 12 are extinguished and the ambient lighting level is relatively high, no light is transmitted through the substrate 13. The image B printed on the front of the apertured sheet 14 then becomes visible by virtue of the fact that the ambient lighting in front of 'the system in brighter than that being transmitted through the apertured sheet 14. The front of the substrate 13 is white and thus any reflected light passing
through the apertures 16 appears to be white and does not affect the image B. Indeed, when the image B is viewed from a distance, it is not readily apparent that the image B is printed on an apertured sheet. The surface of the mesh 14 on which the image B is provided is 3-dimensional and this helps to distract the viewer's eye from the presence of the apertures 16. Another reason that the apertures 16 are less visible is that the 3- dimensional front and rear surfaces of the mesh 14 confine the angle ex, through which light can pass through the apertures 16. Thus, only a very small amount of light passes through the apertures 16 to illuminate the substrate 13 and less of the light reflected off the substrate 13 passes back through the apertures 16. In this manner, the level of the white light passing through the apertures has a negligible effect on the image B .
The reduction in the amount of light allowed to pass through the apertures 16 also has the effect of darkening the image A when the level of light is such that image is being viewed. This has the effect of darkening the image A to the extent that a proportion of black can be removed from the printing of the image A.
A display system in accordance with this invention is thus simple in construction and yet is able to display two images A, B.
In the embodiment shown, the images A, B can be changed independently of each other. However, in an alternative
■embodiment, the substrate 13 and apertured sheet 14 may be fastened together, so as to make it easier to change both images together.
In a further embodiment, control means may be provided for controlling the lamps 12 according to the lighting levels in front of the second image B. It is also envisaged that means could be provided for illuminating the front of the second image B, in order to make the image B visible. Control means
could also be provided for gradually changing the relative lighting levels, so that the images A,B gradually merge.