AU2003252764C1

AU2003252764C1 - Changing Sign System

Info

Publication number: AU2003252764C1
Application number: AU2003252764A
Authority: AU
Inventors: Geoffrey Francis Fontaine
Original assignee: AXENT HOLDINGS Pty Ltd
Current assignee: AXENT HOLDINGS Pty Ltd
Priority date: 2002-10-04
Filing date: 2003-10-06
Publication date: 2011-09-01
Anticipated expiration: 2023-10-06
Also published as: AU2003252764B2; AU2003252764A1

Abstract

A changing sign system for use as variable speed limit sign on roadways including: a display panel; 5 a central numeric displaying area formed on the display panel by a plurality of light emitting structures which when activated can display a selected one of at least two possible speed limit displays, each of the at least two possible speed limit displays corresponding to a respective speed limit of at least two possible speed limits, the at least two possible speed limits including a normal speed limit; 10 an annulus formed by a plurality of outer circles on the display panel around the central numeric displaying area by a plurality of light emitting structures; a control means for selecting the selected speed limit display from the at least two possible speed limit displays according to an input criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus to 15 display the selected one of the at least two possible speed limit displays; wherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on the display panel, when the system is in use, with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits and while 20 simultaneously indicating a change of speed limits when a speed limit different to the normal speed limit is displayed on the a central numeric displaying area, and therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus.

Description

P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Invention Title: Changing Sign System The following statement is a full description of this invention, including the best method of performing it known to me: CHANGING SIGN SYSTEM 5 This invention relates to a changing sign system and to an apparatus useable in such system. It is particularly related to a changing sign system for use as variable speed limit signs on roadways but is not limited to that use. Existing speed signs, which are typically static, have to be a black number on a white 10 background with a red outer circle (annulus) using reflective material. (In accordance with Australian Standards, as incorporated herein by reference.) This style of sign is important and particularly the annulus. If speed sign structures were allowed to have varying forms, users of the roadways would not be able to identify the sign as a speed sign. Instead it could merely be a highway number or parking space indicator or other 15 sign. It is therefore imperative to retain speed signs within this narrow defined structure. The applicant has recently developed new technology and manufactured and operated variable speed limit signs (VSLS) in Australia, which incorporate a flashing annulus to 20 comply with the Australian Standards and the law in respect of a regulatory traffic device. The VSLS are electronic and typically incorporate the use of white light emitting diodes (LEDs) to form the number, red LEDs to form a plurality of outer rings which together form the annuls and a static black background. 25 VSLSs can be used along roadways or bridges, such as the Westgate Bridge in Melbourne, Australia, where there is a likelihood of a change in road condition, such as high wind or sun glare. Instead of a normal maximum safe speed indication of, say, 100 kilometres per hour a hazard lower maximum speed can apply. The VSLS would be switched to the lower maximum speed when a certain wind speed is detected or the 30 sun happens to be at the most distracting level.

However such signs have the disadvantage that they merely advise of the current speed limit. Therefore the driver coming upon the sign would not know that there is anything different to normal. Clearly the lower maximum speed limit is determined according to the expected effect of the hazard. 5 Sometimes the expected hazard might have variable effect such as variable wind speed or variable amounts of material spilled onto the road surface. It is therefore imperative that the driver is not only aware of the lower determined speed limit but also aware that this is a lower limit due to a hazard so that the driver also drives with extra caution in 10 case of the lower determined speed limit not being sufficiently low. Variable signs can also be used at school crossings, school zones and shopping strips. At these places, for safety reasons, a lower speed limit applies at the start and end of school time. It has been well documented that children, and particularly young 15 children, have "tunnel vision" in that they see and concentrate on what is before them but not on the activity in their peripheral vision. In the times before and after school they are not good at looking out for motor vehicles. Also their sense of excitement after being dismissed from school can result in a general lack of concentration. It is imperative therefore that drivers not only be aware of the determined lower speed limit 20 but be aware that it is now a high hazard time and children could be crossing the road at any time without due care. One solution could be to include a second light such as a flashing amber hazard light where the flashing is caused by a rotating shield around the light such as often used on 25 towing vehicles or used with blue and red lights on emergency vehicles. However the use of a second light increases the installation wiring and costs. Further there is the high likelihood of a misunderstanding by the driver since there is no shown connection between the two lights. This misunderstanding is increased since the two lights must be sufficiently spaced to be clearly seen separately and will need to be spaced 30 sufficiently to avoid the glare of one blocking the other. - 2- Another possible solution is to use variable message signs (VMS) to display speed related messages. This will need a much larger sign so that it can display a plurality of alphanumeric characters and must be programmed. Further it is necessary to scroll through a message and therefore must be repeated. The timing of the scroll might not 5 be sufficient for all roadway users to read at the time they are passing the sign. Further, the reading of the sign is a distraction to driving in a similar manner to the use of mobile telephones while driving, this distraction could be increasing the number of road accidents rather than the intention of the sign advising of hazards to decrease the 10 number of road accidents. Still further, the costs of variable message signs can be ten times the costs of single image signs. It is therefore an object of the invention to provide an improved variable speed limit sign, which fulfils the requirement of showing a lower maximum speed limit but also 15 advising of the hazard while maintaining the restrictive requirements of being identifiable as a speed limit sign. In accordance with a first aspect of the invention there is provided a changing sign system for use as variable speed limit sign on roadways including: 20 a display panel; a central numeric displaying area formed on the display panel by a plurality of light emitting structures which when activated can display a selected one of at least two possible speed limit displays, each of the at least two possible speed limit displays corresponding to a respective speed limit of at least two possible speed limits, the at 25 least two possible speed limits including a normal speed limit; an annulus formed by a plurality of outer circles on the display panel around the central numeric displaying area by a plurality of light emitting structures; a control means for selecting the selected speed limit display from the at least two possible speed limit displays according to an input criterion and for varying part of one 30 or more of the display panel, the central numeric displaying area or the annulus to display the selected one of the at least two possible speed limit displays; -3a/cwherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on the display panel, when the system is in use, with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits and while 5 simultaneously indicating a change of speed limits when a speed limit different to the normal speed limit is displayed on the a central numeric displaying area, and therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus. 10 In accordance with a second aspect of the invention there is provided a changing sign system for use as variable speed limit sign on roadways including: a display panel; a central numeric displaying area formed on the display panel by a plurality of light emitting structures which when activated can display a selected one of at least two 15 possible speed limit displays, associated with at least two possible speed limits each indicating change of conditions and which when activated can display a normal speed limit display associated a normal speed limit indicating normal conditions; an annulus formed by a plurality of outer circles on the display panel around the central numeric displaying area by a plurality of light emitting structures; 20 a control means for selecting the selected speed limit display according to an input criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus to display, when selected, the selected one of the at least two possible speed limit displays; wherein the sign system fulfils the criteria of being a speed display sign by always 25 showing a number in a circle on the display panel, when the system is in use, with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits, when selected, while simultaneously indicating a change of speed limits from the normal speed limit, and therefore a change in conditions, by the varying of part of one or more of the display 30 panel, the central numeric displaying area or the annulus. -3b/c- In accordance with a third aspect of the invention there is provided a changing sign system for use as variable speed limit sign on roadways including: a display panel; a central numeric displaying area formed on the display panel by a plurality of light 5 emitting structures which when activated can display a selected one of a number of possible speed limit displays; an annulus formed by a plurality of outer circles on the display panel around the central numeric displaying area by a plurality of light emitting structures; a control means for selecting the selected speed limits display according to an input 10 criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus; wherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on a display panel while being able to indicate a selected one of at least two possible speed limits and while simultaneously indicating a change 15 ---- Continued Page 4-- -3c/cof speed limits, and therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus. It is to be understood that one of the possible speed limit displays is a "blank" sign, 5 indicating no fixed speed limit other than the maximum in the given jurisdiction. In one aspect the annulus is formed by three to five outer rings of light emitting structures and the change of conditions is indicated by flashing some of those outer rings while always retaining one ring on to fulfil the criteria of being a speed display 10 sign by always showing a number in a circle on a display panel. Generally the central numeric displaying area is formed by a plurality of white light emitting diodes while the annulus is formed by red light emitting diodes and the display panel forms a black background. Preferably, the display panel is included with a frame. 15 The criterion to which the control means responds can be an external sensor such as wind sensor, light sensor or the like. In another form there can be a programmed time and speed limits such as usable at time-defined hazards such as schools or sunset. In a further embodiment, the criterion could be receipt of an external signal from a control centre such as a freeway control centre or the like. The response is then made 20 according to the input criteria and selects one of at least two possible speed limits and varies part of one or more of the display panel, the central numeric displaying area or the annulus. In order that be invention can be more readily understood an embodiment will be 25 described by way of illustration only with reference to the drawings wherein: Figure 1 is a diagrammatic view of a changing sign system in accordance with an embodiment of the invention in one state of display; and Figure 2 is a diagrammatic view of a changing sign system in accordance with the embodiment of Figure 1 in a second state of display. 30 - 4- Referring to the drawings there is shown a changing sign system for use as variable speed limit sign (11) on roadways. The sign includes a frame having a front square display panel (21). A central numeric displaying area (25) is formed on the display panel (21) by a plurality of light emitting structures (29) which when activated can 5 display a selected one of at least two possible speed limits. An annulus (27) is formed by a plurality of outer circles on the display panel (21) around the central numeric displaying area (25) by a plurality of light emitting structures. 10 A control means (not shown) is included in the changing sign system (11) for selecting the selected one of at least two possible speed limits which is 80 kilometres per hour in Figure I and 50 kilometres per hour in Figure 2. This speed limit is changed according to an input criterion and varies in this embodiment the annulus (27). 15 The annulus (27) is formed by four outer rings of light emitting structures and the change of conditions is indicated by flashing some of those outer rings while always retaining one ring on to fulfil the criteria of being a speed display sign by always showing a number in a circle on a display panel. 20 The central numeric displaying area (25) is formed by a plurality of white light emitting diodes while the annulus (27) is formed by red light emitting diodes and the display panel (21) forms a black background. 25 The changing sign system (11) thereby fulfils the criteria of being a speed display sign by always showing a number in a circle on a display panel while being able to indicate a selected one of at least two possible speed limits and while simultaneously indicating a change of speed limits and therefore a change in conditions by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus. 30 5- The fabrication and supply of all components for the changing sign system of the invention shall be in accordance with all relevant Australian Standards or, in the absence of same, with appropriate international standards. All installation works, where necessary, shall conform to the relevant road authority specifications that are in 5 force from time to time. Examples of such specifications include VicRoads specifications for installations in Victoria, Australia. The following related specifications and standard drawings are defined and incorporated herein by reference: i. Manual of uniform traffic control devices, Part 2: Traffic control devices for general use AS 1742.2 and particularly Regulatory Sign R4-1 10 ii. Road Signs - Specifications AS 1743 iii. Degrees of Protection provided by enclosures for electrical equipment (1P code) AS 1939 and particularly IP55 iv. SAA Wiring Rules AS 3000 v. Colour Displays Section 2 and section 3.2.2 of AS 2144 15 vi. Electromagnetic Compatibility - Generic Emission Standard AS/NZS 4251 vii. Approval and test specification - Electric cables - Thermoplastic insulated for voltages up to and including 0.6/1kV AS 3147 viii. Approval and test specification - General requirements for electrical equipment AS 3100 20 ix. Retroreflective materials and devices for road traffic control purposes, Part 1: Retroreflective materials AS 1906.1 x. Road Rules - Victoria and particularly Rule 21 xi. VicRoads Guidelines "Variable Speed Limits on Freeways (Draft) xii. VicRoads Traffic Engineering Manual, Volumes I and 2 25 The sign and support structure is constructed from durable materials treated to ensure optimum performance under prolonged exposure to atmospheric and site conditions. Such materials is rated to withstand the effects of solar radiation and to withstand wind forces. 30 The sign enclosure is constructed from marine grade sheet aluminium and is suitably reinforced and braced to facilitate the erection and continued operation of the unit in the - 6intended application. All external metal sections of the completed housings is powder coated or baked enamel finish. Such treatment ensures that deterioration due to atmospheric and/or local environmental conditions has no detrimental effect on the structural integrity or visual appearance, including colour fading, of the finished housing 5 for a period not less than ten years. The interior and exterior of the housing shall be free from sharp edges or projections to avoid injuries. The colour of the finish is matt black and the active display area of the sign is surrounded on all sides by a matt black border to enhance the conspicuity of the illuminated sign face. 10 The sign housing incorporates a lockable door located on the rear housing and provides access to all internal components of the sign for both installation and maintenance purposes. A suitable venting and air circulation system and a suitable moisture inhibitor is used. The venting and air circulation system provides air circulation and means for keeping dust and dirt from the internal areas of the sign enclosure. The use of air filters 15 that require frequent servicing will not be accepted. The front viewing window includes a high impact clear plastic anti-glare sheeting of an approved casting grade acrylic copolymer or polycarbonate. The size of the window area is sufficient for the sides and bottom edges of the display face to be fully visible at viewing 20 angles of between 450 and 30* to the display face, which is substantially vertical. The sign enclosure design incorporates means to adjust the angle of the viewing window in the mounted sign to an angle normal to the road surface during installation and commissioning. The door and window are fitted with effective weatherproof seals of suitable materials such as neoprene rubber. The design of the seals and fastening methods ensure sustained 25 weatherproofing of the sign for the life of the unit. The sign is mounted directly on a column or structure and shall be secured through the base of the sign or from a side-supporting frame of the enclosure. The mounting method ensures that the rear section of the housing and the face of the display modules are vertical 30 with provisions for adjustment. The sign is suitably aligned to point to the centre of the - 7carriageway at a distance of 250 metres from the face of the sign. Access for all power supply, control and communication cabling is through the centre of the column. The display face consists of a red annulus on a black background with white numerals 5 within the annulus. The numerals are centrally located within the red annulus. When displaying other than the normal speed i.e. 100 km/h the sign is capable of flashing part of the inner diameter of the red annulus. The approximate amount of the annulus capable of flashing is preferably in accordance with the following table: Sign Dimensions Approximate amount of the inner diameter of the Size annulus to be flashing as a percentage of the total thickness of the annulus A 550 mm x 550 mm with 450 mm diameter 50% annulus and 200 mm sized numbers. B 750 mm x 750 mm with 600 mm diameter 25% and 50% annulus and 240 mm sized numbers. C 1100mm x 11oomm with 900 mm diameter 20% and 40% annulus and 320 mm sized numbers. 10 While the inner diameter of the annulus is flashing, the remaining portion of the outer diameter of the annulus shall remain on to retain the regulatory status of the sign. The flash rate of the annulus is fully programmable and preferably is between 50 and 60 cycles per minute. The off time is the same as the on time. 15 - 8- The required display technology is either fibre optic display matrix or light emitting diodes (LEDs). Complete blanking of one display and simultaneous generation of the next required display effects display changing. The total time for such an operation is not greater than 0.2 seconds. The sign control system permits total flexibility in the selection 5 of time functions such as blanking times. These times are selectable through the sign controller's system configuration menu, available both locally and remotely. As an example only, when fibre optic technology is used to generate the sign display the optical source is a 10 volt 50 watt quartz halogen dichroic reflector lamp. Such lamps are 10 specifically designed for high temperature, exterior applications and incorporate fly leads fitted with spade fittings. The lamp produces a luminous flux of 270 lumens and has a life span of 6000 hours. The reflector is constructed of corrosion resistant material. Each primary lamp has a 15 secondary back-up lamp, which is automatically illuminated when the primary lamp fails. A lamp indication facility, visible without opening the housing is provided to show the status of the lamps. The display matrix plates of the fibre optic system are constructed from a 3mm thick sheet 20 of rigid material with a matt black finish. The matrix plates and fibre optic restraining ferrules are mounted so that the axis of each pixel is perpendicular to the plane of the plate. The photometric performance of the optical system provides total light transmission efficiency not less than 75%. On axis determination, the luminous intensity of a single 25 light guide is not less than 15 candela for 14* spread systems. The luminous intensity of a single light guide at the extremity of the nominated arc, which is 14*, left, right or below the axial line, is not less than 35% of the axial intensity. The total luminance of the display, on axis, is not less than 4,000 cd/m 2 . The luminance and /or luminous intensity values for a dimmed display is not more than 70% and not less than 30% of the undimmed 30 output. The resultant displays exhibit uniform light and colour distribution across the illuminated area. The uniformity of display intensity is such that the ratio of the average - 9luminous intensity of the total display to the average luminous intensity of any portion of not more than 10% of the sample is not less than 0.75 and not more than 1.25. When light emitting diodes (LEDs) are used to create the display for this sign the 5 luminance intensity and chromaticity co-ordinates of a symbolic display is similar to the fibre optic details above. Individual LEDs are wired so that a failure of any one LED will result in the loss of not more than 6% of the total LEDs in the sign display. The sign automatically shuts down in the event that less than 80% of the total number of LEDs in a display is illuminated. When in the dimmed state the luminous intensity of the display, 10 measured when new, falls into the range of 50% to 75%. Although this invention has been described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and numerous changes in the details of construction and 15 combination and arrangement of parts can be resorted to without departing from the spirit and scope of the invention. It should be understood that the above is a description of the preferred embodiments of the invention but the disclosure of the invention is not limited to those embodiments. Clearly 20 other variations that would be understood by people skilled in the art without any inventiveness are included within the scope of the invention. - 10-

Claims

1. A changing sign system for use as variable speed limit sign on roadways including: a display panel; a central numeric displaying area formed on the display panel by a plurality of light 5 emitting structures which when activated can display a selected one of at least two possible speed limit displays, each of the at least two possible speed limit displays corresponding to a respective speed limit of at least two possible speed limits, the at least two possible speed limits including a normal speed limit; an annulus formed by a plurality of outer circles on the display panel around the 10 central numeric displaying area by a plurality of light emitting structures; a control means for selecting the selected speed limit display from the at least two possible speed limit displays according to an input criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus to display the selected one of the at least two possible speed limit displays; 15 wherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on the display panel, when the system is in use, with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits and while simultaneously indicating a change of speed limits when a speed limit different to the normal speed limit is 20 displayed on the a central numeric displaying area, and therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus.

2. A changing sign system according to claim 1 wherein indicating the change of 25 speed limit from the normal speed limit, and therefore a change in conditions, comprises having a first annular portion of the annulus formed by the light emitting structures flash to indicate the changed conditions while having a second annular portion of the annulus constantly illuminated to assist with fulfilling the criteria of always showing a number in a circle. 30 -11-

3. A changing sign system according to claim 2 wherein the first annular portion of the annulus comprises an inner annulus and the second annular portion of the annulus comprises an outer annulus. 5

4. A changing sign system according to claim 3 wherein the percentage of the total thickness of the annulus flashed when indicating the change of speed limit from the normal speed limit, and therefore a change in conditions, is between 20% and 40%.

5. A changing sign system according to claim 4 wherein the display panel is of the 10 approximate dimensions of 1100mm x 1100mm with approximately a 900mm diameter annulus and approximately 320mm sized numbers being adapted to be shown on the central numeric displaying area.

6. A changing sign system according to claim 3 wherein the percentage of the total 15 thickness of the annulus flashed when indicating the change of speed limit from the normal speed limit, and therefore a change in conditions, is between 25% and 50%.

7. A changing sign system according to claim 6 wherein the display panel is of the approximate dimensions of 750mm x 750mm with approximately a 600mm diameter 20 annulus and approximately 240mm sized numbers being adapted to be shown on the central numeric displaying area.

8, A changing sign system according to claim 6 or 7 wherein the percentage of the total thickness of the annulus flashed when indicating the change of speed limit from the 25 normal speed limit, and therefore a change in conditions, is 50%.

9. A changing sign system according to any one of claims 2 to 8, in which the annulus flashes at a rate of between approximately 50 and 60 cycles per minute. 30

10. A changing sign system according to claim 9, in which the off time of the flash is the same as the on time. -12-

11. A changing sign system according to any one of claims I to 10 wherein the central numeric displaying area is formed by a plurality of white light emitting diodes while the annulus is formed by red light emitting diodes and the display panel forms a black 5 background.

12. A changing sign system according to any one of claims 1 to 11, in which the control means varies part the annulus in response to an external sensor. 10

13. A changing sign system according to claim 12, in which the external sensor is a wind sensor or a light sensor.

14. A changing sign system according to any one of claims I to 11, in which the control means varies the annulus in response to receipt of an external signal. 15

15. A changing sign system according to claim 14, in which the external signal is from a control centre.

16. A changing sign system according to any one of claims 1 tol5, in which the control 20 means varies the annulus according to pre-programmed times.

17. A changing sign system for use as variable speed limit sign on roadways including: a display panel; a central numeric displaying area formed on the display panel by a plurality of light 25 emitting structures which when activated can display a selected one of at least two possible speed limit displays, associated with at least two possible speed limits each indicating change of conditions and which when activated can display a normal speed limit display associated a normal speed limit indicating normal conditions; an annulus formed by a plurality of outer circles on the display panel around the 30 central numeric displaying area by a plurality of light emitting structures; -13- a control means for selecting the selected speed limit display according to an input criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus to display, when selected, the selected one of the at least two possible speed limit displays; 5 wherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on the display panel, when the system is in use, with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits, when selected, while simultaneously indicating a change of speed limits from the normal speed limit, and 10 therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus.

18. A changing sign system according to claim 17 wherein indicating the change of speed limit from the normal speed limit, and therefore a change in conditions, comprises 15 having a first annular portion of the annulus formed by the light emitting structures flash to indicate the changed conditions while having a second annular portion of the annulus constantly illuminated to assist with fulfilling the criteria of always showing a number in a circle. 20

19. A changing sign system according to claim 18 wherein the first annular portion of the annulus comprises an inner annulus and the second annular portion of the annulus comprises an outer annulus.

20. A changing sign system for use as variable speed limit sign on roadways including: 25 a display panel; a central numeric displaying area formed on the display panel by a plurality of light emitting structures which when activated can display a selected one of a number of possible speed limit displays; an annulus formed by a plurality of outer circles on the display panel around the 30 central numeric displaying area by a plurality of light emitting structures; -14- a control means for selecting the selected speed limit display according to an input criterion and for varying part of one or more of the display panel, the central numeric displaying area or the annulus; wherein the sign system fulfils the criteria of being a speed display sign by always 5 showing a number in a circle on a display panel while being able to indicate a selected one of at least two possible speed limits and while simultaneously indicating a change of speed limits, and therefore a change in conditions, by the varying of part of one or more of the display panel, the central numeric displaying area or the annulus. 10

21. A changing sign system according to claim 20, in which the annulus is formed by three to five outer rings of light emitting structures and the change of conditions is indicated by flashing some of those outer rings while always retaining one ring on to fulfil the criteria of being a speed display sign by always showing a number in a circle on a display panel. 15

22. A changing sign system according to claim 20 or claim 21, in which the central numeric displaying area is formed by a plurality of white light emitting diodes while the annulus is formed by red light emitting diodes and the display panel forms a black background. 20

23. A changing sign system according to any one of claims 20 to 22, in which, when displaying other than the normal speed, the sign is capable of flashing part of the annulus.

24. A changing sign system according to claim 23, in which, when the sign is of the 25 approximate dimensions of 550mm x 550mm with approximately 450mm diameter annulus and approximately 200mm sized numbers, the approximate amount of the diameter of the annulus to be flashing, as a percentage of the total thickness of the annulus, is 50%.

25. A changing sign system according to claim 23, in which, when the sign is of the 30 approximate dimensions of 750mm x 750mm with approximately 600mm diameter annulus and approximately 240mm sized numbers, the approximate amount of the diameter of the -15- annulus to be flashing, as a percentage of the total thickness of the annulus, is between 25% and 50%.

26. A changing sign system according to claim 23, in which, when the sign is of the 5 approximate dimensions of 1100mm x 1100mm with approximately 900mm diameter annulus and approximately 320mm sized numbers, the approximate amount of the diameter of the annulus to be flashing, as a percentage of the total thickness of the annulus, is between 20% and 40%. 10

27. A changing sign system according to any one of claims 20 to 26, in which the display panel is included with a frame.

28. A changing sign system, substantially as hereinbefore described, with reference to the examples, 15 MIDDLETONS Attorneys for the Applicant AXENT HOLDINGS PTY LTD -16- MARKED-UP COPY ABSTRACT A changing sign system for use as variable speed limit sign on roadways including: a display panel: 5 a central numeric displaying area formed on the display panel by plurality of light emitting strcture which when activated can display a selected one of at least two possible speed limit displays. each of the at asttwo ps e eed limit displays corresponding to a respective speed limit of at least two possible speed limits. the at least two possible speed limits including a normal speed limit; 10 an annulus formed by a plurality of outer circles on the display panel around the central numeric displaying area by a plurality of light emitting structures: a control means for selecting the selected speed imtdsplay m the at least two possible speed limit displays according to an input criterion and for varying part of one or more of the display panel the central numeric dis laying area or the annulus to 15 display the selected one of the at least two possible speed limit displays wherein the sign system fulfils the criteria of being a speed display sign by always showing a number in a circle on the display panewen thesystem is in use. with the circle being illuminated by the light emitting structures of the annulus, while being able to indicate a selected one of the at least two possible speed limits and while 20 simultaneously indicating a change of speed limits when a sped limit different to the normal. peed limit is displayed on the a central numeric displaying area and therefore a change in conditions. byte varyngof part. o onerm eo e display pel the central numeric displaying aea or the annulus.