GB2258750A

GB2258750A - Flourescent tube illuminated display sign.

Info

Publication number: GB2258750A
Application number: GB9116247A
Authority: GB
Inventors: Alan Heaton
Original assignee: HI LITE SIGNS Ltd
Current assignee: HI LITE SIGNS Ltd
Priority date: 1991-07-27
Filing date: 1991-07-27
Publication date: 1993-02-17
Anticipated expiration: 2011-07-27
Also published as: GB9116247D0; GB2258750B

Abstract

An illuminated display sign comprising a translucent display panel 24, at least one fluorescent tube 16, 22 spaced from a rear face of the display panel, and a light screen formed on the rear face of the display panel adjacent each fluorescent tube and arranged to screen the light emitted therefrom in order to produce gradient free illumination of the display panel, each light screen comprising a central axis of high opacity (31, Figure 2) surrounded by a peripheral area of lower opacity (34), the opacity of the peripheral area diminishing as a function of the distance from the central area, the central area being elongate extending parallel to the longitudinal axis of the fluorescent tube, the central axis terminating inboard from opposite ends of the tube so as to extend from the majority of the length of the tube. Suitably, each screen comprises a series of clusters of material, each cluster being in the form of a group of progressively increasing radii located around a solid centre, the solid centre of adjacent clusters forming the central area (31) and the concentric rings of adjacent clusters forming the peripheral area (30). <IMAGE>

Description

FLUORESCENT TUBE ILLUMINATED DISPLAY SIGN This invention generally relates to illuminated signs having a light source in the form of a fluorescent tube, where a gradient free illumination across the display sign is required.

In order to produce compact display signs having a fluorescent tubes, it is desirable to place the tube as closely as possible to the front display panel. However, this results in an effect known as 'striping'. This arises because the intensity of light falling on a given area of the display panel varies depending on its proximity to the light source, with the result that undesirable local bright areas are produced. The closer the fluorescent tube is to the front display panel, the greater the 'striping' effect.

Accordingly, it is an object of the present invention to providing a compact sign, which is illuminated by a fluorescent tube, and which does not suffer from the aforementioned problem of striping.

The present invention provides an illuminated display sign comprising a translucent display panel, at least one fluorescent tube spaced from a rear face of the display panel, and a light screen formed on the rear face of the display panel adjacent each fluorescent tube and arranged to screen the light emitted therefrom in order to produce gradient free illumination of the display panel, each light screen comprising a central axis of high opacity surrounded by a peripheral area of lower opacity, the opacity of the peripheral area diminishing as a function of the distance from the central area, the central area being elongate extending parallel to the longitudinal axis of the fluorescent tube, and the central axis terminating inboard from opposite ends of the tube so as to extend for the majority of the length of the tube.

Preferably each tube has a pair of electrodes located inboard of the ends of the tube, the terminal ends of the associated light area terminating at locations substantially corresponding to the respective locations of said electrodes.

Preferably each light screen comprises a series of clusters of material having their centres disposed along an axis parallel to a longitudinal axis of the corresponding fluorescent tube, each cluster being in the form of a group of progressively increasing radii located around a solid centre, the solid centre of adjacent clusters forming said central area and the concentric rings of adjacent clusters forming the peripheral area.

Preferably the adjacent solid centres of adjacent neighbouring clusters overlap to define a continuous solid area.

Suitably, the radii of the discrete, concentric rings within each cluster may increase geometrically.

Alternatively or additionally, the thickness of each ring may be varied.

The material is preferably in the form of an ink, which may be screen printed onto the display panel. The ink is chosen to be compatible with the material of the light screen, which may be acrylic, PVC or glass, for example, and a tinted clear ink may be used, the depth of tinting depending on the density required.

Exemplary embodiments of the invention will now be described with reference to the following drawings, in which: Figure 1 shows a side view of apparatus in accordance with the present invention; and Figure 2 illustrates the arrangement of the ink on the back of the display panel in relation to a fluorescent tube.

Figure 1 shows a side view of an illuminated sign 10.

the sign 10 has a rear face 12 with a first fluorescent tube 16 and a second fluorescent tube 22 mounted thereon by means of sets of clips 18. The sign 10 is also provided with a display panel 24 which is made from a translucent sheet material such as plastics material or glass. The display panel 24 has a light diffuser or screen 28 formed on the rear face 26 thereof, adjacent the light sources 16,22. In this embodiment of the invention the light screen is in the form of an ink 28 of high opacity relative to the display panel 24, which is capable of blocking a portion of the light incident thereon.

Figure 2 depicts the arrangement of the ink 28 in relation to a fluorescent tube 22 when viewed from in front of the display panel 24, the display panel 24 not being shown. The ink 28 being printed such that directly between a pair of electrodes 32, there is a central area of high opacity 31, and a peripheral region of lower opacity 30.

This arrangement is achieved in the present embodiment by screen printing a series of circular clusters 30 with solid centres (three being marked) along an axis corresponding to a longitudinal axis of the fluorescent tube 22 in a region between the electrodes 32. Each cluster 30 has the aforementioned solid centre of diameter substantially equal to that of the tube 22 and a group of discrete, concentric rings 34 of geometrically increasing radii. In the embodiment shown, the clusters 30 are printed so closely together that a continuous solid region of high opacity is created in an area 31 corresponding to the region between the electrodes 32.

Accordingly, this arrangement can give rise to a gradient free sign 10 when viewed from the front of the display panel 24, because the distribution of ink 28 on the rear surface 26 of the display panel compensates for the reduced amount of light received from the fluorescent tube 22 by the display panel in peripheral areas corresponding to regions adjacent the fluorescent tube 22 and to regions defined by the electrodes 32 back to their associated ends.

In another embodiment of the invention, the distance between consecutive concentric rings may be constant.

In a still further embodiment of the invention, consecutive rings may be of differing thickness.

In the embodiment shown in Figure 2, the high opacity region 31, is shown as a completely black region having a continuous layer of ink printed thereon. It should be understood that some light passes through this region as the ink is not completely opaque to light, but as previously described, merely blocks a portion of the light incident thereon. In another embodiment, the ink 24 may however be substantially completely opaque.

The clusters may be made up of other discrete shapes of progressively increasing linear dimensions and/or thickness, for example square, triangles or other polygons etc.

For a given combination of fluorescent tube 22 and display panel 24 at a given separation, it is necessary experimentally to determine the relative surface density of ink 28 which needs to be applied to the various regions of the display panel 24. The ink 28 may then be applied in a pattern for example in accordance with any of the hereinbefore described embodiments.

Signs in accordance with the present invention may employ fluorescent tubes of different sizes, for example 5/8" (1.6cm), 1" (2.54cm) or 1.5" (3.8cm) diameter tubes.

In one arrangement using 1" (2.54cm) diameter tubes 16,22, the spacing between the tubes and the light screen 28 is between 3-Smm. The size of tube and the distance between the tubes and light screen determine the thickness, number and spacing of the rings 34 and the width of the solid cluster centres.

As already mentioned, the ink used is one which is compatible with the material of the display panel 24 and it has been found that basically clear inks which are then tinted to the required depth of colour are satisfactory.

Claims

1. An illuminated display sign comprising a translucent display panel, at least one fluorescent tube spaced from a rear face of the display panel, and a light screen formed on the rear face of the display panel adjacent each fluorescent tube and arranged to screen the light emitted therefrom in order to produce gradient free illumination of the display panel, each light screen comprising a central axis of high opacity surrounded by a peripheral area of lower opacity, the opacity of the peripheral area diminishing as a function of the distance from the central area, the central area being elongate extending parallel to the longitudinal axis of the fluorescent tube, the central axis terminating inboard from opposite ends of the tube so as to extend from the majority of the length of the tube.

2. An illuminated sign according to claim 1, wherein each tube has a pair of electrodes located inboard of the ends of the tube, the terminal ends of the associated light area terminating at locations substantially corresponding to the respective locations of said electrodes.

3. An illuminated sign according to claim 1 or 2 wherein each light screen comprises a series of clusters of material having their centres disposed along an axis parallel to a longitudinal axis of the corresponding fluorescent tube, each cluster being in the form of a group of progressively increasing radii located around a solid centre, the solid centre of adjacent clusters forming said central area and the concentric rings of adjacent clusters forming the peripheral area.

4. An illuminated sign according to claim 3, wherein the adjacent solid centres of adjacent neighbouring clusters overlap to define a continuous solid area.

5. An illuminated sign according to claim 3 or 4, wherein the radii of concentric rings within each cluster increase geometrically.

6. An illuminated sign according to claims 3, 4 or 5, wherein the thickness of each ring is varied.

7. An illuminated sign according to any of claims 3 to 6, wherein each cluster is printed in the rear face of the display panel using ink of the same opacity for the solid centres and the concentric rings.

8. An illuminated sign according to claim 7, wherein the ink is clear, medium or tinted.

9. An illuminated sign according to any preceding claim, wherein the spacing between the rear face and the fluorescent tube is in the range of 3 to 5mm.

10. An illuminated sign constructed, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.