GB2350226A - Traffic sign - Google Patents

Abstract

A traffic road sign comprising a programmable rectangular continuous matrix display of light emitting diodes (LED's) for displaying multiple lines of text and pictorial signs in at least two colours; and computer control means for causing the sign to display variable messages relevant to the context of road users in the form of pictorial signs and multiple lines of text of variable height and of mixed heights in two or more colours. A preferred mounting structure for the road sign includes a single column with a horizontal portion cantilevered from the top of the column.

Description

i 2350226 METHOD AND APPARATUS FOR DISPLAYING VARIABLE MESSAGES TO ROAD

USERS This invention relates to a method and apparatus for displaying variable messages to road users, more particularly but not exclusively to traffic on highways, especially motorways, for example to warn drivers of the presence of fog, accidents, incidents, lane closures congestion and temporarily altered speed limits.

As well as fixed road signs such as those giving route directions, motorways in the UK are provided with variable message displays comprising matrices of lamps which can be selectively illuminated to display text and pictograms. Two main types of sign are in use. The earlier design comprises a relatively small low level sign located between carriageways and capable of displaying a relatively limited range of messages controlled by a central control office, for example, the word 'FOG' or a lane closure wicket. More recent signs comprise multi-line text displays controllable from a central traffic control centre and able to give a much wider range of messages. The characters of the displayed message are each produced by a respective character display device although, in addition, usually at one end of the message display, there may be a specific display device for showing a symbol such as a speed numeric speed limit. Of course, the information has to be seen easily on motorways with fast moving traffic and so, especially because respective character display devices are used, the signs are quite large and hence heavy. This results in a quite substantial supporting structure with a gantry or massive cantilever column, especially as maintenance ladders and walkways are provided. The columns 2 are designed to withstand substantial impact which adds to the size and expense. Also, large signs may well have an unwelcome environmental impact in some locations.

According to one aspect of the invention, there is provided apparatus for displaying variable messages to road users, the apparatus comprising a road sign including a programmable rectangular continuous matrix display of light emitting diodes (LED's) for displaying multiple lines of text and pictorial signs in at least two colours; and computer control means connected to said sign and programmed for causing the sign to display messages relevant to the context of road users in the form of pictorial signs and text of variable height and of mixed heights.

According to a second aspect of the invention there is provided a method of communicating variable messages to road users, the method comprising displaying textual and pictorial information to said users by means of a road sign including a programmable rectangular continuous matrix display of light emitting diodes (LED's) for displaying multiple lines of text and pictorial signs in at least two colours; and computer control means connected to said sign and causing the sign to display messages relevant to the context of road users in the form of pictorial signs and text of variable height and of mixed heights.

Said computer may comprise memory means holding data indicative of messages relevant to road users, for example speed limit numbers, accident symbols and text, lane closures wicket symbols and the like, and means for causing selected ones of the pre-stored messages to be downloaded to the 3 road sign.

The apparatus and method to be described with reference to the drawings preferably comprises a fully programmable LED display matrix capable of full or twin colour display of variable height uppercase and lowercase text characters, including variable height characters within the same display or message, with a high resolution. Also pictograms or symbols may be displayed while flashing amber beacons may or may not be provided as required. At least part of the area of the display matrix is capable of full or twin colour display but it may not be necessary for the whole of the display to be like this, in particular the second of the twin colours (red) may not be required on the whole panel.

For a better understanding of the invention and to show the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a diagrammatic view of showing two Imown types of motorway road sign in use in the UK; Figure 2 is a diagrammatic view of part of a road sign according to the invention; Figure 3 is a perspective view of the figure 2 road sign with a first form of mounting structure, the sign being shown in position next to a motorway; 4 Figure 4 is a diagram showing how the figure 3 sign is best located; Figures 5, 6, and 7 are respective views corresponding to figure 4 but showing second, third and fourth mounting arrangements for the sign, and Figures 8, 9 and 10 are respectively a front view, an end view and a plan view of another road sign.

Referring to Figures 1 and 2, at present in the UK two main types of motorway road sign are in use. The older design comprises a relatively low level display 1 mounted in the central area between the two motorway carriageways and comprising a matrix of lamps which can be selectively energised to display a limited number of messages, for example the word 'FOG'or, as shown at 2, a wicket symbol indicating a lane closure. At the four corners of the matrix, flashing amber beacons 3 are usually provided to increase the impact of the message. More recently, relatively much larger overhead signs comprising a multi-line text display 6 have come into use. The display may comprise for each character to be displayed a 7 x 5 matrix of lamps or light emitting diodes. The size of each character is fixed according to the size of each matrix. The signs often have maintenance platforms 4 reached by fixed or stowable ladders (not shown) and are supported by gantries (not shown) or are cantilevered on quite massive columns 5.

Referring to Figures 2 to 4, the sign according to the invention comprises a square or rectangular continuous matrix 20 of light emitting diodes (LED's) of the kind sometimes used for advertisements and action replays in football stadia and the like. The matrix might have dimensions of 1760 mm. by 1760 mm and a pixel pitch of say 20 nun so that it has a resolution of 88 by 88 pixels. The matrix 20 is mounted on a barrel shaped backing board 21 of say 2000 mm by 2000 mm in size, the board being coloured black to match the non-energised parts of the display matrix. The matrix and/or the backing board could be larger (or smaller) depending on requirements. The display is capable of displaying two colours over the whole matrix, i. e. so that it can provide off-white text and red and off-white pictograms such as the red triangle and white accident symbol and text seen in Figure 3. Each pixel may comprise a single variable colour LED or to provide colour control and/or increase the brightness of each pixel it may comprise several LEDs in suitable pattern. On the backing board at the comers of the display matrix are four amber beacon lamps 23 and four red beacon lamps (not shown) which can be switched on and off to flash and hence accentuate the displayed message. Each of the lamps is preferably also a respective LED matrix display or there could be just four lamps each with the capability of displaying the colours amber and red alternately. As an alternative to the lamps, if the LED's in the appropriate locations of the main display matrix itself are able to display the colour amber, the beacons can be created by the display itself. It is not necessary of course that only two colours should be displayable - it is preferred in fact that several colours, including red, yellow, off-white and white, even a relatively full range thereof within the expanding limits of the LED display technology, should be available at every pixel of the display. This gives most adaptability albeit at additional cost. As mentioned earlier, the two or multi-colour capability could also extend to only part of the display area.

6 The display matrix is controlled by a display driver circuit 24 which, in turn, is controlled by a computer 25 and data entry equipment 26 (along with similar road signs - not shown - at other locations) at a central traffic monitoring station 27 located at a distance from the road sign. The computer 25 and display driver circuit 24 are operable for controlling the display in a fully programmable manner, i.e. so that the whole display can be caused to show a pictogram or speed limit or text message; or to show a smaller pictogram while part of the display shows a text message with smaller or larger text as desired and with mixed character sizes and with upper case and lower case text or mixed case text as required.

By enabling variable height upper and lower case characters to be displayed, the character height can be set according to the length of the message to be read and comprehended by a driver, time needed to read message and space available on the display panel.

As shown in Figures 3 and 4, the road sign 19 is cantilevered on a column 30 having a smooth curved transition 31 between the column upright 32 and cross-piece 33. The column may be manufactured in parts or as a single continuous structure. Because the sign using a continuous LED matrix can be much less heavy than the more recent type of sign shown in Figure 1 with a series of smaller matrices for respective characters of the text to be displayed, the column 30 can be much less bulky. This means that the column upright can be up to several metres away from the carriageway, if the land is available, and that in turn means that no great impact protection 7 needs to be provided and the support need not be designed to withstand impact. Figure 4 shows the ideal location for the signal with the cantilever column upright 32 four or five metres away from the hard shoulder of the motorway. A hard standing area is provided next to the column and/or beneath the sign to enable the sign to be reached by a 'cherry-picker' type of mobile maintenance vehicle with a lifting platform. No ladders and fixed rear platforms are provided for maintenance as is necessary with the usual type of text display presently in use. Of course, a maintenance platform could be provided if required by the circumstances.

The mounting structure can be modified if required as shown in Figures 4 to 7 although the Figure 4 arrangement is preferred. Figure 5 shows a cantilever column with a square corner 41 between upright 42 and crosspiece 43. Figure 6 shows the sign mounted on two straight columns 51. Figure 7 shows a sign mounted on a single column 6 1. Also of course the panel may even be gantry mounted in the same way as some existing road signs.

It is preferred that the signs of figures 2 to 7 should comprise protection from the weather and from the build-up of traffic grime - a particular need in this respect is protection from wind-driven snow. For this, the matrix display can be covered by a screen of transparent material such as glass or plastics material and/or there may be provided heating elements or heating devices for warming the display and its components to prevent frost and condensation forming and to keep snow from setting thereon.

Naturally, each sign is designed and located to achieve pre-set objectives 8 regarding readability (assimilation) of the messages. This is achieved by adjusting variables such as angles at which the sign is set up, i.e. which is directed at a particular aim point upstream of the sign so that, depending upon the likely speed of the traffic on the road, the sign is best seen and assimilated by approaching motorists. It may be useful also to provide the sign with a sun-shield, for example a louvre arrangement, over the whole display or over individual pixels.

The display matrix of the sign shown in figure 2 has dimensions of 1760 mm x 1760 mm with a 20 mm pixel pitch in an array of 88 x 88 pixels. As alternatives to these dimensions, the display matrix could be up to say 2600 mm x 2600 mm and the array could comprise 130 x 130 pixels each of a size of 20 mm. In general, between 75 x 75 pixels and 150 x 150 pixels is the preferred range for the array. However, the size of the array might be in the range from 1500 mm x 1500 mm to 3000 mm x 6500 mm or even larger if required by the circumstances. Instead of a 20 mm pixel pitch, a greater or smaller pitch could be used, for example 32 mm.

Instead of the display comprising light emitting diodes arranged to be viewed directly, fibre optic arrangements could be provided to deliver light to the image plane of the display from a separately located LED array.

The road sign of Figures 8 to 10 comprises a display unit 19 similar to that of Figures 2 to 7 and a curved cantilever mounting structure 70 similar to that of Figures 3 and 4. The mounting structure 70 of Figures 8 to 10 comprises a column including a lower portion 71 with a flange 72 at the bottom. The 9 flange 72 is fixed by bolts 73 which are mortared into a concrete foundation 74. The major part of the foundation is below ground level 75. At the top of the column portion 7 1, and at the bottom of an upper portion 76 of the column, there are respective annular flanges 77 and 78. The flanges 77 and 78 are bolted together by bolts 79 via bolt-holes 80 which, in one or the other or both of the flanges 77 and 78, are acutely slotted so that, by loosening and then re-tightening the bolts 79, the upper portion 76 can be adjusted about the vertical axis of the column. This in turn adjusts the direction in a horizontal plane of the road sign display 19. The mounting structure 70 also comprises a horizontal portion 81 continuous with the column portion 76 via a smoothly curved transition portion 82. Three spaced straight box section members 83 are suspended from the horizontal portion 81 of mounting structure 70 by way of bolted together flanges welded to the tops of the members 83 and to the portion 8 1. Each member 83 comprises two welded on lugs 84 by which the display unit 19 is connected to the structure 70. For this, the display unit has respective lugs 85 or any suitable alternative fixings by which the display unit can be set to face in a direction inclined downwardly within a vertical plane.

The unit 19 comprises a housing 90 with a transparent screen 91 at the front and containing heating and/or air blowing apparatus (not shown) for defrosting and preventing snow from settling on the display and to prevent the formation of condensation. Louvres not shown may also be provided, for example within the housing 90 behind the screen 91 to make the display easier to see in direct sunlight.

A short section of plastics pipe 92 extends from the portion 83 to drain any water gathered therein and lead it away from over the display 19.

The cabling from the display unit leads via plastics conduits (not shown) down through the column to ducts 93 in the foundation 74 and thence, below ground, to appropriate junction boxes (not shown) near the road sign.

The LED display matrix (not shown) within unit 19 is a two-colour display able to produce, at each pixel, the colours red and either yellow, yellowwhite or white, and having a pixel pitch of 20rnm the display is able to produce variable height characters, say between 280mm. and 420mm in height with an aspect ratio (height to width ratio) of say 1.6:1 for upper-case characters and 1:1 for lower case characters. The display matrix is coupled via a display driver (not shown) to a computer system not shown in Figures 8 to 10 but which could be like the system 27 of Figure 2.

Claims (6)

11 CLAIMS

1. Apparatus for displaying variable messages to road users, the apparatus comprising a road sign including a programmable rectangular continuous matrix display of light emitting diodes (LED's) for displaying multiple lines of text and pictorial signs including, in at least part of the display, in at least two colours; and computer control means connected to said sign and programmed for causing the sign to display messages relevant to the context of road users in the form of pictorial signs and text of variable height and of mixed heights.

2. Apparatus according to claim 1, wherein said computer comprises memory means holding data indicative of messages relevant to road users, for example speed limit numbers, accident symbols and text, lane closures wicket symbols and the like, and means for causing selected ones of the messages to be downloaded to the road sign.

3. Apparatus according to Claim 1 or 2, wherein the matrix display and computer are operable for display in text messages with proportionally spaced characters.

4. Apparatus according to Claim 1, 2 or 3, including a mounting structure for supporting said road signs and including a single column with a projecting portion cantilevered from the top of the coluirm and supporting the road sign.

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5. Apparatus according to Claim 1, wherein the mounting structure comprises adjustment means for adjusting the position of the rod sign.

6. A method of communicating variable messages to road users, the method comprising displaying textual and pictorial information to said users by means of a road sign including a programmable rectangular continuous matrix display of light emitting diodes (LED's) for displaying multiple lines of text and pictorial signs in at least two colours; and computer control means connected to said sign and causing the sign to display messages relevant to the context of road users in the form of pictorial signs and text of variable height and of mixed heights.

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