LIGHTING ARRANGEMENTSDESCRIPTIONThe present invention relates to lighting arrangements, more particularly but not exclusively lighting arrangements for decorative or information purposes.
Lighting arrangements have for some time now been provided both for decorative and information purposes, especially providing safety information.
Lighting arrangements may be provided (for example, in the noses of steps) to indicate in a darkened room the position of a potential hazard (for example the location of the nose of the step); or to indicate a particular escape route.
Various forms of lighting arrangements have been proposed. The majority of the proposals known to us include a series of sub-miniature lamps mounted to provide the information, for example, along the length of a step nose.
It has also been proposed that the sub-miniature lamps be replaced by LED's which operate at a lower voltage, are physically more durable and have a longer life than subminiature lamps.
All the arrangements know to us so far which make use of sub-miniature lamps or LED's provide a distinct series of points of lights.
Arrangements have been proposed to provide a continuous strip of light, for example along the nose of a step.
Proposals achieving this include the use of electro-luminescent materials which emit light when an electrical voltage is applied to them. These have been found, however, to have a relatively short life significantly less than that of arrangements including subminiature lamps.
Another proposal for forming a continuous light strip which has been made is to provide a bundle of aligned optical fibres in the form of a tail, harness or tow.
Light passed along the fibres leaks through its sides and so appears to an observer as a continuous strip of light.
Yet again a more recent proposal provides a large diameter single core solid plastics element which acts to transmit light.
Such arrangements have been found to be both complex to install and difficult to maintain.
An object of the invention is to alleviate or overcome the disadvantages of the known proposals and to provide a lighting arrangement appearing to an observer as a continuous strip light.
In accordance with this object the invention provides a lighting arrangement formed of a plurality of individual light sources in closely spaced array.
Desirably, the array is linear.
The individual light sources may be formed in groups, each group being fed from an electrical power supply.
Each group of light sources preferably includes current limiting resistor means.
With advantage the individual light sources are mounted juxtaposed on a printed circuit board.
The printed circuit board may be elongate and be formed with conductive tracks for connection to an electrical supply.
The individual light sources preferably compriseLED's.
Desirably, the printed circuit boards and light sources are mounted within a plastics tube.
The plastics tube may be square in section.
The plastics tube may have two or more surfaces through which light from said light sources pass.
With advantage there are provided two surfaces through which light from said light sources pass.
Desirably, the outermost of said two surfaces is narrower than the innermost of said surfaces.
The plastics tube may be sized to fit within a slot formed in a step nose.
The surface of the plastics tube through which light is emitted is preferably, in use, carried in the step nose at an angle to both the vertical and horizontal.
The material of the plastics tube in which the light sources are mounted is preferably translucent.
The above aspects, features and advantages of the present invention will become apparent from the following description of one arrangement embodying the invention now made with reference to the accompanying drawings, in which:- Figure 1 illustrates a step fitted with a step nose embodying the invention,Figure 2 is an end view of one form of step nose embodying the invention,Figure 3 shows at A and B side and end views of one form of translucent tube in which is mounted a printed circuit board carrying a plurality of LED's and which embodies the invention.
Figure 4 illustrates a printed circuit board layout used in a lighting arrangement of the present invention, Figure 5 illustrates an electrical circuit diagram of a lighting arrangement embodying the invention,Figure 6 illustrates an end view of a second step nose embodying the invention,Figure 7 is a fragmentary prospective view of a second form of translucent plastics tube in which is mounted a printed circuit board carrying a plurality ofLED's and which is for use in the arrangement of Figure 6, andFigure 8 illustrates further an electrical circuit diagram embodying the invention.
Figure 1 schematically illustrates a step in a flight of steps each of which carries a step nose 10 on its leading edge. Nose 10 is formed with a slot 12 receiving a translucent plastics, preferably polycarbonate, tube 14 forming part of a lighting arrangement embodying the invention.
Within the plastics tube 14 there is provided a linear printed circuit board 16 carrying a plurality ofLED's 18.
Figure 2 is an end view of nose 10 showing more clearly the disposition of the various parts so far described. It will be appreciated that slot 12 in nose 10 is at an angle to the horizontal and vertical such that the lighting arrangement formed by the plastics tube 14 is visible to those walking both up and down the steps.
As can be more clearly seen from Figures 3 and 4 the elongate printed circuit board 16 is provided with two continuous tracks 20, 22 at its lower surface.
These two tracks run the length of the printed circuit board (which in accordance with the invention is approximately 400mm but which may be of any preferred length).
The upper surface of the printed circuit board 16 is also formed with two tracks 24, 26 lying respectively above the tracks 20, 22.
Track 24 is continuous and runs the length of the printed circuit board.
Track 26 is, however, intermittent and formed with a series of breaks. In each break in track 26 there is provided a conductive electrical patch 28.
The centre of the upper surface of printed circuit board 16 carries a series of links 30 in groups of nine. Between each group of nine links 30 electrical ties 32 and 33 run from the middle of the printed circuit board to the rail 24 and to the conductive patches 28 respectively.
Resistors 34 are provided to extend through the printed circuit board to provide electrical connection between the track 22 and the patches 28. LED's 18 are connected across adjacent links 30 as shown. In use the tracks 22 and 24 are connected to the positive and negative lines respectively of a 24v DC supply.
It will be appreciated that this configuration gives rise to the electrical circuit diagram shown inFigure 5.
It will be seen that the resistors 34 acts to limit the current flow through the LED's 18. It is envisaged that if the electrical supply is to be 24v DC then resistor 34 would have a value of 220 ohms.
Figure 6 and 7 illustrate a second step nose embodying the present invention which differs from that shown in Figure 1 by providing that the plastics tube 50 housing the LED's 18 is provided with two translucent surfaces 54 and 56 through which the light from the LED's 18 is viewed by an observer. As with the arrangement so far described the LED's are mounted in closely spaced linear array on a printed circuit board 16.
It is to be noted that the outermost surface 56 of the tube 52 shown in Figures 6 and 7 is narrower than the innermost surface 54.
It has been found that this, double, diffuser element above the LED's enhances the continuous nature of the appearance of the LED's as viewed by the observer.
The printed circuit board 16 carrying the LED's 18 and resistors 34 may be, as noted, of indefinite length as is the plastics tube 14 in which they are fitted. When it is desired to fit the lighting arrangement to a step nose 10 as shown in Figures 1 and 2 or Figure 6 the plastics tube 14, 50 and printed circuit board 16 are cut to length - that is to say cut to a length in which they will completely fill the slot 12 running across the nose 10.
It is possible that in cutting the printed circuit board to the desired length a user may cut through a series of LED's attached to a group of links 30. In this case the user could alter the value of the resistor 34 to ensure the same nominal current flows through the remainingLED's 18 in the group or, perhaps, use an additional resistor between a link 30 and the rail 24.
Figure 8 illustrates another way in which the nominal current flow through the LED's 18 in a group may be maintained if a group is shortened when coupling the tube.
In the arrangement of Figure an appropriately valued zener diode 60 is used to compensate for any missing LED's at the end of a run.
The use of a zener diode to compensate for the missing light sources, has the effect of leaving the series resistor unchanged. As a result of this the remaining light sources in the string vary in brightness in the same manner as a complete string if the supply voltage is varied allowing the light sources to be dimmed.
It is noted the plastics tubes 18, 52 are of polycarbonate material but other suitable materials may be used. The tubing is preferably translucent but may be transparent.
It will be appreciated from the foregoing that the lighting apparatus of the present invention provides what to an observer appears to be a continuous strip light through the translucent visible surfaces of the tubes 14, 52.
Although described as being for information purposes in the nose of a step it will be appreciated that embodiments of the invention are usable in other situations. For example the continuous strip of light provided by the apparatus embodying invention may be used for other decorative purposes or to indicate to an individual a possible escape route from a building, ship or airplane.
It will be appreciated that variations may be made to the described arrangements without departing from the scope of the present invention. Among these are the provision of printed circuit boards, supporting the LED's which are non-linear, e.g. in the form of letters or symbols. Although described as using LED's other suitable individual light sources may be used.