AU2005202187B2

AU2005202187B2 - Message Display Sign

Info

Publication number: AU2005202187B2
Application number: AU2005202187A
Authority: AU
Inventors: Jean Marie Gilbert Malepa; Chris Newhouse
Original assignee: Roads and Traffic Authority of New South Wales
Current assignee: Roads and Traffic Authority of New South Wales
Priority date: 2004-05-20
Filing date: 2005-05-19
Publication date: 2009-06-25
Anticipated expiration: 2025-05-19
Also published as: AU2005202187A1

Description

P20131AUOI AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: ROADS & TRAFFIC AUTHORITY OF NEW SOUTH WALES Actual Inventors: JEAN MARIE GILBERT MALEPA CHRIS NEWHOUSE Address for Service: HODGKINSON McINNES PAPPAS Patent & Trade Mark Attorneys Level 3, 20 Alfred Street MILSONS POINT NSW 2061 Invention Title: "Message Display Sign" Details of Associated Provisional Application: 2004902705 filed 20 May 2005 The following statement is a full description of this invention, including the best method of performing it known to us: 2 MESSAGE DISPLAY SIGN TECHNICAL FIELD This invention relates to display signs and, in particular, to variable message display signs. 5 The invention has been developed primarily for use with light emitting diode (LED) based variable message display signs and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to this field of use and is applicable to other illuminated message display signs. 10 BACKGROUND LED based variable message display signs, for example roadside-type variable message signs, include a planar array of pixel elements formed from LED clusters (typically one LED per cluster to about 15 of more) disposed in a weather-proof housing having a 15 transmission window at a front. The pixel elements are electronically controlled to display a predetermined message. The LED based pixels are not necessarily disposed in an exactly planar arrangement and may be offset with respect to each other in a vertical plane. However, the optical axis of 20 the LED(s) comprising the pixels are substantially parallel. Recently, variable message roadside-type display signs have been developed with both a higher spatial density of pixel elements and improved control software allowing higher resolution messages such as text or graphics to be provided. 25 The transmission windows used in such variable message display signs are typically composed of a coated or uncoated polycarbonate or safety glass, and the LED(s) used in the pixel elements are relatively bright. The transmission window can reflect light so as to reduce the contrast ratio seen by an observer of the sign. Similarly, glare from the pixel elements in combination with the transmission window can be problematic in cases where 30 an observer approaches and needs to see a display sign but sees a distorted view with undesirably reduced contrast ratio. This especially occurs with outdoor signs.

3 It is known that anti-glare and anti-reflection coatings can be applied to transmission window during manufacture or retrofitted to minimise loss of observable contrast of the message displayed. However, such coatings are typically costly to apply as well as maintain, for example, requiring special cleaning solvents. Dirt and dust adhered to the 5 transmission windows also adds to the loss of contrast problem so that transmission windows need regular cleaning otherwise complex messages or graphics can become difficult to read. In US Patent No. 5,833,355 there is disclosed an LED based illumination lens assembly 10 configured to cover one or more LED based pixels simultaneously. The lens assembly of this patent is configured to maximise the amount of emitted light in a preferred direction being substantially perpendicular to the transmission window. Unfortunately, whilst improving the light efficiency, glare and reflection problems akin to those noted above largely remain and cause a loss of contrast. 15 US Patent No. 5,515,253 provides a refractive lens arrangement for an LED array in illuminated roadside signs. The lens arrangement of this patent is configured to provide an observer with the appearance of a "solid" light source where the spaces between the LEDs in an array are substantially in distinguishable to an observer. Although providing a clear 20 visual source, signs such as these still suffer from glare and reflective problems by an observer viewing through a transmission window. This is exemplified with illuminated roadside-type display signs. It is an object of the invention to provide a message display sign that overcomes or 25 substantially ameliorates one or more of the deficiencies of the prior art, or to provide a useful alternative. SUMMARY OF INVENTION 30 According to a first aspect of the invention, there is provided a message display sign including a plurality of light emitting pixel elements disposed substantially in a vertical plane; and a substantially planar and transparent transmission window disposed adjacent the light emitting pixel elements; characterised in that an angle of between 920 and 1100 is 4 provided between the plane of the transmission window and the optical axis of the light emitting pixel elements, the predetermined pixel elements in the substantially vertical plane are horizontally offset from other pixel elements and the distance between each pixel element along its optical axis and transmission window is substantially constant. 5 Preferably, a roadside display sign is provided wherein each light emitting pixel element is formed from a cluster of between one and fifteen light emitting diode (LED) elements. Preferably, the roadside display sign includes a weatherproof enclosure wherein one side 10 of the transmission window is exposed and the sign is configured to be fixedly mounted to a fixed or mobile support and to variably display predetermined messages. Preferably in one embodiment said cluster of LED elements are held in place by a holder unit. 15 Preferably said holder unit comprises a plurality of ribs some of which are either interposed between said LED elements or located along the periphery of said cluster of LED elements. 20 Preferably said ribs are adapted to substantially prevent said LED elements from deflection. Preferably said ribs are configured such that in use the holder unit shields the LED elements from direct sunlight. 25 Preferably said holder unit is configured to physically maintain the viewing angle of said LED elements to a predetermined specification. According to a second aspect of the invention, there is provided a method of providing an 30 illuminated message display sign, the method including the steps of disposing a plurality of light emitting pixel elements in a substantially vertical plane with each pixel element having a substantially parallel optical axis being substantially perpendicular to the vertical plane, the pixel elements disposed adjacent a transmission window characterised in that an 5 angle of between 920 and 1100 is provided between the plane of the transmission window and the optical axis of the light emitting pixel elements. It can therefore be seen that there is advantageously provided a roadside display sign and 5 method of making same where the optical axis direction of a plurality of light emitting pixel elements is disposed at an angle of between 920 and 1100 relative to the plane of a transmission window. BRIEF DESCRIPTION OF DRAWINGS 10 Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: FIG. 1 is a partial schematic side view of a roadside display sign according to one embodiment; and 15 FIG. 2 is a partial schematic side view of a roadside display sign according to a second embodiment; and FIG. 3 is a partial schematic side view of the sign of FIG. 1 showing a housing. FIG. 4 is a partial schematic side view of a roadside display sign according to a third embodiment. 20 MODE OF CARRYING OUT INVENTION Referring to the drawings generally, each FIG. shows a variable roadside display sign 1 configured to be disposed adjacent a roadside. However, the message display sign 1 can be configured to be disposed in any preferred location such as indoors. It is noted that in 25 the FIGS. like components are denoted with like numerals. FIG. 1 shows a roadside display sign 1 according to one embodiment and FIG. 2 shows a roadside display sign according to another embodiment. In the embodiment of FIG. 1, the variable message roadside display sign 1 includes an 30 array of LED-based pixel elements 2, although only two are shown. That is, each pixel element 2 is formed from a cluster of two LED elements 3. However, it is noted that any preferred number of LED elements can be used to form each cluster, and typically may be made of one up to about fifteen LED elements 3. Further, the plurality of LED-based pixel 6 elements 2 can be disposed in a two-dimensional square or other array geometry (not illustrated). One or more of the pixel elements 2 are horizontally offset, either angled or stepped with 5 reference to each other, by a predetermined amount. However, they need not be offset at with respect to each other at all. The light emitted from each LED 3 comprising each pixel element 2 is directed substantially in the same direction. This direction defines a pixel element optical axis 5. 10 The number of pixel elements 2 disposed in a given area will define the available spatial resolution of the sign 1 to display indicia. It will be appreciated that the use of pixelated variable message signs has increased recently due to their ability to display predetermined messages, including graphics, which is desirably viewed by observers. 15 A planar transmission window 4 is spaced apart from and disposed adjacent to the pixel elements 2. One face of the window 4 is exposed to the environment. The transmission window 4 is further disposed such that its plane of window 4 forms an angle of between 920 and 1100 with the pixel optical axis 5. Similarly, the pixel optical axis 5 can be tilted to form an angle a between 92* and 110* with a vertically disposed transmission window 4. 20 Put in other words, the plane of transmission window is tilted between 20 to 200 relative to the plane formed by the pixel elements 2. In the embodiment shown, the distance between each pixel element 2 and hence each LED element 3 forming each pixel element 2 to the transmission window 4 is substantially constant. This distance is denoted "d". However, 25 the angle formed between the transmission window 4 and the pixel optical axis 5 can be varied between 920 and 110* as is preferred. Although not shown, the message display sign 1 can be configured for use as a roadside display sign. In these embodiments, the display sign 1 is disposed in a weather-proof 30 housing where the exposed face of the transmission window 4 is configured to be disposed substantially perpendicular to observers in on-coming traffic. Typically, such roadside display signs 1 are fixedly mounted onto a post or other supporting structure. It is noted, 7 however, the signs can be mounted onto a trailer or the like which also includes a power source for the sign 1. Referring now to FIG. 2, there is shown a second embodiment of a roadside display sign 1 5 in which each pixel element 2 is formed from a 'cluster' of only one LED 3. As with the case in FIG. 1, the pixel elements 2 in the roadside display sign 1 of this FIG. are offset with respect to each other so that the distance between the transmission window 4 and each LED 3 is substantially constant. 10 It can therefore be seen that there is advantageously provided a roadside display sign 1 and method of making same where the optical axis direction of a plurality of light emitting pixel elements 2 is disposed at an angle of between 920 and 110* relative to the plane of transmission window 4. 15 FIG. 3 shows the sign 1 of FIG. 1, additionally showing a sign housing 8. The housing 8 can be any conventional housing and is preferably a weatherproof enclosure. FIG. 4 depicts a third embodiment of a variable message display sign 1, which like that of the above described first and second embodiments, has a plurality of light emitting pixel 20 elements 2 disposed at angle a of between 920 and 1100 relative to the plane of transmission window 4. However, in this embodiment the cluster of LED elements 3 are held in place by a holder unit 10 having a plurality of elongate ribs 1 la and 1 lb. The ribs 11 a are interposed between adjacent LED elements 3, whilst ribs 11 b are located adjacent the LED elements 3 at the periphery of the cluster. 25 The ribs 11 a, 11 b are configured such that they maintain the LED elements in a predetermined angle and protects them such that the risk of the LED elements 3 being deflected during the working life of the sign is eliminated or substantially minimised. Furthermore, the ribs 1 la and 1 lb are configured such that the holder unit 10 shields the 30 LED elements 3 from direct sunlight at a critical predetermined solar angle. The holding unit 10 also physically maintains the LED viewing angle to a predetermined specification. In this embodiment, the LED viewing angle is about 300.

8 The holder unit 10 is preferably of a moulded plastic construction and allows for the clusters of LED elements 3 to be mounted to a printed circuit board at a predefined angle, which in this embodiment is about 8* to the vertical. 5 The holder unit 10 provides a cost efficient means of ensuring the angle relationship between the LED elements 3 and the transmission 4. The foregoing describes only preferred embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing 10 from the scope of the invention.

Claims

1. A message display sign including: a plurality of light emitting pixel elements disposed substantially in a vertical plane; 5 and a substantially planar and transparent transmission window disposed adjacent the light emitting pixel elements; characterised in that an angle of between 920 and 1100 is provided between the plane of the transmission window and the optical axis of the light emitting pixel elements. 10

2. A roadside display sign as claimed in claim 1 wherein predetermined pixel elements in the substantially vertical plane are horizontally offset from other pixel elements. 15

3. A roadside display sign as claimed in claim 1 or 2 wherein the distance between each pixel element along its optical axis and transmission window is substantially constant.

4. A roadside display sign as claimed in any one of the preceding claims wherein each light emitting pixel element is formed from a cluster of one or more light emitting diode 20 (LED) elements.

5. A roadside display sign as claimed in any one of the preceding claims including a weatherproof enclosure wherein one side of the transmission window is exposed. 25

6. A roadside display sign as claimed in any one of the preceding claims wherein the sign configured to be fixedly mounted to a fixed or mobile support.

7. A roadside display sign as claimed in any one of the preceding claims being configured to variably display predetermined messages. 30

8. A roadside display unit as claimed in claim 4, wherein said cluster of LED elements are held in place by a holder unit. 10

9. A roadside display unit as claimed in claim 8, wherein said holder unit comprises a plurality of ribs some of which are either interposed between said LED elements and others are located along the periphery of said cluster of LED elements. 5

10. A roadside display unit as claimed in claim 9, wherein said ribs are adapted to substantially prevent said LED elements from deflection.

11. A roadside display unit as claimed in claims 9 or 10, wherein said ribs are configured such that in use the holder unit shields the LED elements from direct sunlight. 10

12. A roadside display unit as claimed in any one of claims 10 to 11, wherein said holder unit is configured to physically maintain the viewing angle of said LED elements to a predetermined specification. 15

13. A method of providing an illuminated message display sign, the method including the steps of disposing a plurality of light emitting pixel elements in a substantially vertical plane with each pixel element having a substantially parallel optical axis being substantially perpendicular to the vertical plane, the pixel elements disposed adjacent a transmission window characterised in that an angle of between 920 and 1100 is provided 20 between the plane of the transmission window and the optical axis of the light emitting pixel elements.

14. A roadside display sign being substantially as herein described with reference to the accompanying drawings. 25

15. A method of providing a roadside display sign, the method being substantially as herein described with reference to the accompanying drawings. Dated this 19 fi day of May, 2005 30 ROADS AND TRAFFIC AUTHORITY OF NEW SOUTH WALES HODGKINSON McINNES PAPPAS Patent Attorneys for the Applicant 35