IES20090131A2 - An illuminated display apparatus - Google Patents

Abstract

An illuminated display apparatus comprises an image-bearing panel 14, a diffusion panel 12 arranged next to and nin register with the image-bearing panel, and a light source 20 for illuminating the image-bearing panel through the diffusion panel. The light source comprises a series of LED modules 20 distributing along a channel memeber 16 extending along an edge of the diffusion panel. To compensate for the fall-off of the intensity of illumination of the image away from the lift edge, which would normally occur with an edge-lit display, the diffusion panel 12 is designed so that its light transmissivity increases with increasing distance form the LED modules 20. <Figure 1>

Description

An illuminated Display Apparatus This invention relates to an illuminated display apparatus .

According to the present invention there is provided an illuminated display apparatus comprising an image-bearing panel, a diffusion panel arranged next to and in register with the image-bearing panel, and a light source for illuminating the image-bearing panel through the diffusion panel, the light source being distributed along an edge of the diffusion panel, wherein over at least a region of the diffusion panel adjacent the said edge the light transmissivity through the panel increases with increasing distance from the light source.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a first embodiment of the invention.

Figure 2 is a cross-section through the lower part of the 25 embodiment of Figure 1.

Figure 3 shows an alternative form of LED-retaining clip to that shown in Figures 1 and 2.

Figure 4 shows the graduated light transmissivity of the diffusion panel in Figures 1 and 2. and 2, an illuminated jorm of a light box comprises a rectangular frame 10 forming a peripheral housing for the light box. Rectangular diffusion and image-bearing panels 12, 14 respectively are mounted in register next to one another in an edge of the frame 10 (the right hand edge as shown in Figures 1 and 2). The panel 14 is transparent or translucent and carries an image (text and/or graphics) to be displayed. A second diffusion panel 12' and image-bearing panel 14' may be similarly mounted in the opposite edge of the frame 10 in the case where a respective image is to be displayed on each side of the box; otherwise the opposite edge of the frame can be blanked off with an opaque panel.

An elongated channel member 16 of substantially constant cross-section is set into the inside surface of the frame 10, the channel member extending at least along the lower horizontal bar 18 of the frame. A plurality of LED modules 20 are set into the channel 22 of the channel member 20, the modules 20 being distributed substantially along the full length of the bar 18 and connected in series by electrical conductors 24. The LED modules 20 are retained in the channel 22 by convex spring clips 26 whose opposite edges engage under internal projections 28 running along opposite sides of the channel near its base, the clips extending over and trapping the conductors 24 between the modules 20. Alternatively, Figure 3, concave spring clips 30 may be used, whose opposite edges engage under internal projections 32 running along opposite sides at the top of the channel.

The LED modules 20 may be of the type marketed by LED Inc. of 1601 Fairview Dr. #22, Carson City, NV 89701, USA, or by Lighting & Electronic Design, Inc. of 141 Cassia Way STE C, Henderson, NV 890141, USA. Depending on the width of the LED modules 20, they may either sit on rails 34 extending along the base of the channel 22, as shown in the drawings, or sit between these rails in the case of narrower modules.

In use, light emitted by the LED modules 20 into the interior of the light box is reflected around inside the box and emerges through the diffusion panel 12 and imagebearing panel 14 so that the image on the latter is visible to an external viewer. The diffusion panel 12 is made of, or bears a layer of, a light diffusion material so that the light from the LED modules is diffused as it passes into and through the image-bearing panel. Since in this embodiment the LED modules 20 are distributed only along the lower edge of the diffusion panel 12, the intensity of illumination of the panel 12 will be greatest adjacent that edge and decrease with increasing distance away from that edge. This would normally lead to a fall-off of the intensity of illumination of the image in the vertical direction.

In an attempt to compensate for this, the diffusion panel 12 is designed so that its light transmissivity increases with increasing distance from the LED modules 20, i.e. it becomes progressively more opaque towards the lower edge. This is shown in Figure 4, where 50 represents a narrow vertical strip of a graduated coating 50 applied to the diffusion plate 12. At the bottom 52 the coating 50 is fairly opaque, having a relatively low density of pinhole apertures. Near the middle 54 the density of pinhole apertures has increased, while at the top the graduated coating 50 is nearly transparent. The graduated coating 50 may be in shades of grey or a colour. The graduated coating 50 may be printed directly onto an opal glass, Ifc acrylic, polycarbonate or other diffusion panel 12, or it may be printed into an initially clear panel 12 and backed up with translucent white or coloured vinyl film to provide the necessary diffusive properties.

The channel member 16 may be made by extrusion of, e.g., aluminium, PVC or steel. It is preferably made of a material, and of a wall thickness (e.g. 1mm or less), which allows the member to be bent at least to a gentle curve in a plane normal to its base and parallel to its longitudinal axis. This will allow the member to be deformed to fit along the edge of curved or circular display panels.

Although in the above embodiment the diffusion panel 12 was illuminated only along its bottom edge, this is only satisfactory for relatively small area displays, say 300mm high. For larger displays, say up to 600mm high, the diffusion panel 12 could be illuminated along both its top and bottom edges by setting a second channel member 16 with LED modules 20 into the inside surface of the top bar 36 of the frame 10, the LED modules illuminating the diffusion panel 12 in a downward direction. In such a case the graduated coating 50 would be designed such that the light transmissivity through the panel 12 increases with increasing distance from the top and bottom of the frame 10 to reach a maximum in a central region of the panel. In other embodiments the diffusion panel could be illuminated from all four sides of the frame 10, and the graduated coating designed accordingly. Also, the display need not be rectangular; for example, it could be circular with LED modules extending around all or part of the frame.

IEO 9 ο 1 31 The above embodiment of display apparatus has the following advantages: - The LED channel member 16 eliminates the need to individually bond LED lighting modules to a surface using either double sided tape or adhesive. Research has confirmed that a large percentage of LED lighting pod manufacturers recommend this method of fixing.

Once the LED pods are positioned they are difficult to reposition without causing damage to the double sided adhesive tape. Removal of this tape is extremely difficult and time consuming when making way for the fitting of replacement or relocated LED modules.

- The LED channel member eliminates the need to individually screw fix or bolt each LED module individually. Normally various rows (depending on sign panel height) are required to successfully back illuminate sign panels. Each row consists of 10 to 15 pods per running meter as an average requirement to back light a sign panel within a sign case or backlight a 3D letter/ logo face panel.

- A double sided sign case of approximately 1200 high x 3000mm long requires in the region of 400 individual LED lighting modules to successfully give proper and even illumination when back lighting sign panels using conventional techniques. Using the present embodiment reduces this quantity by as much as two thirds, i.e. 160 LED modules approximately. The pods can be positioned top and/or bottom of the display (illuminating up/down) and also in horizontal rows at selected distances apart depending on brightness of light output from the LEDs.

JEQ 9 0 1 3 1 - Using the channel member reduces labour by as much as 75% when fitting the LED modules, as not only does it dispense with bonding or fixing the modules but also with the use of applying self adhesive tape between each pod gap. Proper adhesion must last for the duration of LED module, which is approximately 5 years.

- The channel member's reusable clips eliminates the use of double sided adhesive tape, adhesive or any form of mechanical fixing when fitting LED modules. All these methods are extremely time consuming compared to using the present embodiment. The channel member and clips also act a cable tidy as it is an effective method of ensuring that both cables and cable connectors are neatly retained within the channel member. This is an important factor to ensue that shadows caused on the display panel by untidy cables/connectors are eliminated.

- Substantial savings on the cost of servicing is also achieved by reducing the time spent when replacing LED modules. Sign 'down time' and costs during servicing are also reduced.

- There are no adhesive or mechanical fixings of LED modules, other than fitting the channel member. The channel member is also designed to simplify and speed up and adjusting the lighting intensity and/or effects made by LED modules in comparison with other fixing methods for LEDs described above.

- The distance between the modules can be extended (to the maximum of the interconnecting cable) or reduced by 'I / simply sliding the pods within the channel member. Additional clips overlapped may be used when extending. Clips reduced in size or renewed can be used when reducing the distance between modules.

Large savings on illumination costs are also achieved by reducing electricity consumption when using the present embodiment.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims (5)

Claims

1. An illuminated display apparatus comprising an image-bearing panel, a diffusion panel arranged next to and in register with the image-bearing panel, and a light source for illuminating the image-bearing panel through the diffusion panel, the light source being distributed along an edge of the diffusion panel, wherein over at least a region of the diffusion panel adjacent the said edge the light transmissivity through the panel increases with increasing distance from the light source.

2. An apparatus as claimed in claim 1, comprising a pair of light sources distributed respectively along opposite substantially parallel edges of the diffusion panel, wherein the light transmissivity through the panel increases with increasing distance from each light source to reach a maximum in a central region of the panel.

3. An apparatus as claimed in claim 1 or 2, wherein the or each light source comprises a series of LED modules distributed along the respective edge of the diffusion panel.

4. An apparatus as claimed in claim 3, wherein the LED modules are set into a channel member which forms part of, or is set into, a frame for the image-bearing and diffusion panels.

5. An apparatus as claimed in claim 4, wherein the frame defines the periphery of a light box, the LED modules illuminating the interior of the light box.