A highway electronic display

Abstract

 The present invention is directed to a highway electronic display comprising a printed circuit board (PCB) having a plurality of light emitting diodes (LEDs), an optics stage, and a display cover. The optics stage comprises an alignment plate and an optics plate, the alignment plate comprising a sheet of opaque material positioned intermediate the PCB and the optics plate and having a plurality of through holes arranged in rows and columns coincident with the LEDs, and the optics plate comprises a sheet of transparent material having a plurality of optical elements arranged in rows and columns coincident with the LEDs. Each optical element comprises a convex boss protruding outwardly from a rear face of the optics plate proximal the LEDs and a cylinder having a diffusing lens protruding outwardly from a front face of the optics plate distal from the LEDs. Each optical element is formed in a single, unitary piece with the sheet of transparent material. The advantage of providing such a highway electronic display is that the optics plate will be more cost effective to manufacture than manufacturing a plurality of individual optical elements.

Description

Introduction

[0001] This invention relates to a programmable highway electronic display. In particular, the present invention relates to a highway electronic display comprising a printed circuit board (PCB) having a plurality of light emitting diodes (LEDs) mounted thereon arranged in rows and columns, an optics stage, and a display cover.

[0002] Programmable highway electronic displays are commonly used to provide information to motorists. Information concerning the driving conditions, speed restrictions, notifications of delays due to traffic jams and other such pertinent information is displayed to the motorists. These programmable highway electronic displays are usually mounted on a gantry that bridges over the highway, or on fixed upright poles along the side of the highway. Alternatively, it is also known for the displays to be mounted on a transportable base so as to enable temporary signage to be displayed on local roads when roadworks are being carried out, or, when traffic restrictions are in place on the local roads.

[0003] The displays comprise a plurality of LEDs that are arranged into a number of pixels. Each pixel comprises one or more LEDs. In order to display information, a set of pixels are illuminated by switching on the one or more LEDs in each of the pixels in the set of pixels. The set of illuminated pixels form an alphanumeric message and/or a symbol on the highway electronic display. The one or more LEDs in each pixel are controlled to switch on and to illuminate for a predetermined amount of time by electronic circuitry on the PCB.

[0004] The LEDs are arranged in an array and are housed in a display cover. The light emitted from each of the LEDs is passed through an optics stage in order to focus and direct the light emitted from the LEDs in a predetermined direction, commonly referred to as a desired viewing region, outwardly from the display towards the approaching motorists.

[0005] There are two main criteria that must be addressed when designing a programmable electronic display. The first is that the light beams emitted from the display are predominately within the desired viewing region that has been selected as being clearly visible from a range of angles for the approaching motorists. The second important criterion is that sunlight falling on the display will not be reflected from the LEDs, or other components, such as to give the illusion that the LED is illuminated when it is not.

[0006] These criteria are currently achieved in highway displays using extremely complex optics stages. Typically, the light from each LED is concentrated into a relatively narrow beam and is subsequently directed outwardly into the desired viewing region. In these displays, each LED is typically housed in a dedicated housing structure specific to that LED. The dedicated housing structure also holds the separate lenses of the optics stage for that LED. Two such highway displays are disclosed in United States patent number US6,249,375 B1 (SILHENGST) and United States patent number US6,078,439 (SILHENGST).

[0007] US6,249,375 discloses an optical element for a programmable traffic sign. The optical element comprises a LED, a converging lens, a separate diverging lens and a shared housing. The light from the LED is concentrated by the converging lens and travels further along the shared housing to the diverging lens which re-directs the light outwardly from the sign. The light emitted from the sign is directed by the diverging lens to be within a pre-determined allowable angle range (i.e. the desired viewing region for the approaching motorists). However, the diverging lens and the length of the shared housing act to prevent incident light from the sun giving an illusion of an illuminated LED when the LED is turned off. The problem with this current solution is that the separate converging and diverging lenses, and the relatively lengthy shared housing provides a complex structure which all increases the cost of manufacture of the optical element. Furthermore, the complexity of the geometrical arrangement of the lenses in the shared housing requires skilled workmen to construct the optical element, and, skilled workmen are also required to diligently and carefully install the optical element. This further increases the cost of manufacture and also increases the installation costs for the traffic sign.

[0008] In a further embodiment disclosed in US6,249,375, the shared housing may be reduced in length. However, this reduction in length increases the probability that incident light from the sun can cause a false illumination on the traffic sign. To counteract this, a diaphragm is positioned intermediate the converging lens and the diverging lens in the shared housing. The diaphragm will absorb some of the incident light from the sun and prevent a false illumination from occurring. However, the inclusion of a further component in the optics stage only further increases the complexity of the optics stage and will increase the cost of manufacture of the optics stage.

[0009] US6,078,439 discloses an optical element for mounting in a front plate of a traffic sign. The optical element comprises a light source such as an LED and a lens element in a shared housing. The shared housing, containing the lens element and the LED, may be then mounted into one of a plurality of cavities found on a front plate of the traffic sign. US6,078,439 attempts to overcome some of the previously mentioned problems by providing a simplified lens arrangement for the optical element. However, each optical element has their own individual lens element, and the cost of manufacturing and installing each lens element in each optical element will still be quite expensive.

[0010] It is a goal of the present invention to provide an apparatus that overcomes at least some of the above mentioned problems whilst providing a simple and inexpensive optics stage.

Summary of the Invention

[0011] According to the invention there is provided a highway electronic display comprising a printed circuit board (PCB) having a plurality of light emitting diodes (LEDs) mounted thereon arranged in rows and columns, an optics stage, and a display cover, wherein that the optics stage comprises an alignment plate and an optics plate, the alignment plate comprising a sheet of opaque material positioned intermediate the PCB and the optics plate and having a plurality of through holes arranged in rows and columns coincident with the rows and columns of the LEDs, and in which the optics plate comprises a sheet of transparent material having a plurality of optical elements arranged in rows and columns coincident with the rows and columns of the LEDs, each optical element comprising a convex boss protruding outwardly from a rear face of the optics plate proximal the LEDs and a cylinder terminating in a diffusing lens protruding outwardly from a front face of the optics plate distal from the LEDs, the convex boss concentrating light emitted from an LED through the cylinder and the diffusing lens re-directing that light into a desired beam, each optical element formed in a single, unitary piece with the sheet of transparent material.

[0012] There are two significant advantages to providing a highway electronic display with an optics plate which comprises a sheet of transparent material having a plurality of optical elements arranged in rows and columns on the sheet. The first advantage is that the optical elements may be manufactured more cost effectively than is currently possible with known electronic displays. In the present invention, a plurality of optical elements are all be formed in a single unitary transparent piece of material. It is therefore far quicker and easier to manufacture such a plurality of optical elements on a single unitary piece of material as the optics plate will be relatively large and easy to handle during the manufacturing process unlike the individual separate optical elements which are relatively small and difficult to handle and manufacture.

[0013] The second advantage of using an optics plate which comprises a sheet of transparent material having a plurality of optical elements arranged in rows and columns on the sheet is that the optics plate is faster and easier to install. A plurality of the optical elements can all be installed and aligned at the same time by a workman. Moreover, the larger optics plate is easier to handle than relative small individual optical elements. During the installation process, the larger optics plate of the invention will be more robust than the smaller, more intricate individual optical elements.

[0014] In a further embodiment, the plurality of LEDs comprise LEDs of two distinct colours, each LED along a row on the PCB being of one distinct colour and each LED along an adjacent row on the PCB being of the other distinct colour such that the PCB comprises alternating rows of coloured LEDs, and, the sheet of transparent material of the optics plate also comprising alternating rows of two distinct coloured transparent materials which correspond to the alternating rows of coloured LEDs on the PCB.

[0015] In another embodiment, a pair of adjacent LEDs in a column on the PCB form a pixel of the highway electronic display, each pixel therefore containing an LED of the two distinct colours.

[0016] In yet a further embodiment, the diffusing lens comprises a roughened outer surface. This roughened surface reduces the possibility that a false illumination can be caused by incident light from the sun, or a different external light source such as a roadside street lamp, a headlight from a vehicle or the like.

[0017] In another embodiment, the diffusing lens comprises a translucent outer surface.

[0018] In yet another embodiment, the diffusing lens comprises a curved outer surface.

[0019] In still a further embodiment, the diffusing lens comprises a downwardly inclined outer surface. The downward inclination of the outer surface of the diffusing lens will further reduce the possibility that a false illumination can be caused by incident light from the sun.

[0020] In still another embodiment, the through holes of the alignment plate are substantially frusto conical in shape terminating in a tubular collar, whereby the through holes taper from the rear of the alignment plate to the front of the alignment plate. This is advantageous as the alignment plate comprises a plurality of robust diaphragms that can be quickly and easily installed in a highway electronic display. The frusto conical shape aids the electronic display to minimise the amount of incident light from the sun that is reflected back as a false illumination of the LED as the frusto conical through hole of the alignment plate forms a diaphragm for the LED that sits in that through hole. A large number of diaphragm forming through holes in the alignment plate can all be quickly installed in relation to the array of corresponding LEDs on the PCB.

[0021] In a further embodiment, the alignment plate is held spaced apart from the PCB so that a tip of each of the LEDs mounted on the PCB enters an open mouth of each of the through holes on the alignment plate.

[0022] Advantageously, a gasket membrane is positioned intermediate the optics plate and the display cover. The gasket membrane will prohibit water and other fluids from damaging the electronic display.

[0023] Preferably, the gasket membrane comprises a plurality of apertures in rows and columns coincident with the rows and columns of LEDs on the PCB.

[0024] In another embodiment, each aperture is surrounded by an upstanding annular collar.

[0025] In a further embodiment, the display plate comprises a plurality of apertures in rows and columns coincident with the rows and columns of LEDs on the PCB.

Detailed Description of Embodiments

[0026] The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only with reference to the accompanying drawings, in which:

Fig. 1 is a front perspective view of a highway electronic display in accordance with the present invention;

Fig. 2 is a rear perspective view of the highway electronic display of Fig. 1;

Fig. 3 is a rear exploded perspective view of the highway electronic display of Fig. 1;

Fig. 4(a) is an isometric view of a printed circuit board (PCB) comprising a plurality of light emitting diodes (LEDs) of the highway electronic display of Fig. 1;

Fig. 4(b) is a plan view of the PCB of Fig. 4(a);

Fig. 4(c) is a side elevation view of the PCB of Fig. 4(a);

Fig. 4(d) is a top elevation view of the PCB of Fig. 4(a);

Fig. 4(e) is an enlarged view of a circled portion of the PCB in Fig. 4(d);

Fig. 5(a) is a wire frame model perspective view of an alignment plate of the highway electronic display of Fig. 1;

Fig. 5(b) is a plan view of the alignment plate of Fig. 5(a);

Fig. 5(c) is a cross-sectional side elevation view of the alignment plate of Fig. 5(b) along lines V-V;

Fig. 5(d) is a cross-sectional top elevation view of the alignment plate of Fig. 5(b) along lines V'-V';

Fig. 5(e) is an enlarged view of a circled portion of the alignment plate in Fig. 5(d);

Fig. 6(a) is an isometric view of an optics plate of the highway electronic display of Fig. 1;

Fig. 6(b) is a plan view of the optics plate of Fig. 6(a);

Fig. 6(c) is a cross-sectional view of the optics plate of Fig. 6(a) along lines VI-VI;

Fig. 6(d) is a cross-sectional view of the optics plate of Fig. 6(a) along lines Vl'-VI';

Fig. 7(a) is an isometric view of a gasket membrane of the highway electronic display of Fig. 1;

Fig. 7(b) is a plan view of the gasket membrane of Fig. 7(a);

Fig. 7(c) is a cross-sectional side elevation view of the gasket membrane of Fig. 7(a) along lines VII-VII;

Fig. 7(d) is a cross-sectional top elevation view of the gasket membrane of Fig. 7(a) along lines VII'-VII';

Fig. 7(e) is an enlarged view of a circled portion of the gasket membrane in Fig. 7(c);

Fig. 8(a) is an isometric view of a display cover of the highway electronic display of Fig. 1;

Fig. 8(b) is a plan view of the display cover of Fig. 8(a);

Fig. 8(c) is a top elevation view of the display cover of Fig. 8(a) showing the apertures in phantom outline;

Fig. 9(a) is a perspective view of an optical element of the highway electronic display of Fig. 1;

Fig. 9(b) is a top elevation view of the optical element of Fig. 9(a);

Fig. 9(c) is a bottom elevation view of the optical element of Fig. 9(a); and,

Fig. 9(d) is a side elevation view of the optical element of Fig. 9(a).

[0027] Referring to Figs. 1-3, there is shown a highway electronic display indicated generally by the reference numeral 100. The highway electronic display 100 comprises a printed circuit board (PCB) 102, an alignment plate 104, an optics plate 106, a gasket membrane 108 and a display cover 110. The highway electronic display 100 comprises a plurality of LEDs 112 which are arranged in an array to form a number of pixels 114 on the highway electronic display 100.

[0028] With reference to Figs. 4(a)-4(e), there are shown more detailed views of the PCB 102. The PCB 102 comprises a plurality of LEDs 112 arranged in an array having eight columns 402 of sixteen LEDs 112 and sixteen rows 404 of eight LEDs 112. Therefore, each column 402 has sixteen LEDs 112 therein and each row 404 has eight LEDs 112 therein. The LEDs 112 are mounted on a backboard 406 of the PCB 102. Adjacent LEDs 112 along a column 402 alternate in colour between a first distinct colour and a second distinct colour, which is to say that adjacent rows 404 of LEDs 112 have a different colour of LED with respect to each other. The backboard 406 further comprises electrical components such as resistors, capacitors, diodes, data buses, processors, memory and the like as is commonly found on PCBs. These electrical components are not shown as they are well understood in the act of PCBs and are not considered necessary to the understanding of this invention. Referring specifically to Fig. 4(e) it can be seen that each LED 112 comprises a light source 408 connected to the backboard 406 of the PCB 102 by wiring 410.

[0029] With reference to Figs. 5(a)-5(e), there is shown in more detail the alignment plate 104. The alignment plate 104 comprises a plurality of through holes 500 arranged in eight columns 502 of sixteen through holes 500 and sixteen rows 504 of eight through holes 500 on the alignment plate 104. The alignment plate 104 is opaque. Referring specifically to Fig. 5(e) it can be seen that each through hole 500 is substantially frusto conical in shape. The through hole 500 comprises a larger mouth 506, to receive at least a tip of each LED (not shown), and a narrower exit hole 508 on the opposing side of the alignment plate 104 to the larger mouth 506. The large mouth 506 tapers towards the narrower exit hole 508 along an frusto conical section 510 that terminates in a cylindrical section 512 proximal the narrower exit hole 508.

[0030] Referring to Figs. 6(a)-6(d), there is shown in more detail the optics plate 106. The optics plate 106 comprises a plurality of optical elements 600 that are arranged in eight columns 602 of sixteen optical elements 600 and sixteen rows 604 of eight optical elements 600 on a baseboard 606. The baseboard 606 is transparent and comprises a rear face onto which light from the LEDs 112 is incident and a front face through which light is emitted.

[0031] The optics plate 106 is made up of a plurality of differently coloured strips. As can be seen in Figs. 6(a) and 6(b), the baseboard 606 is divided into a plurality of strips of coloured transparent material that run laterally across the optics plate 106 and abut to one another. Therefore there are sixteen strips on the baseboard 606. Each strip of coloured transparent material comprises one row 604 of eight optical elements 600. Both the strip of coloured transparent material and the eight optical elements 600 on that strip are formed in a single unitary piece and are all the same colour. Adjacent rows 604 of eight optical elements 600 correspond to adjacent strips of coloured transparent material.

[0032] As previously discussed, each adjacent row 404 of LEDs 112 comprises differently coloured LEDs 112, and correspondingly, each adjacent row 604 of strips of coloured transparent material comprises differently coloured strips of transparent material. Therefore, the sixteen strips that form the sixteen rows 604 on the optics plate 106 alternate between two distinct colours, and, there are two distinct colours on the optics plate 106 shown in Figs 6(a)-6(d). A first colour 612 may be red, and a second colour 614 may be orange. These colours 612, 614 correspond to the colours of the LEDs 112 that also alternate between adjacent rows 404 of LEDs 112.

[0033] Each optical element 600 will be described in greater detail below, but generally speaking each optical element 600 comprises a convex boss 608 on the rear face of the optics plate 106 for converging the light from the LEDs (not shown) and a cylinder 610 on the front face of the optics plate 106 for diffusing the converged light from the LEDs.

[0034] With reference to Figs. 7(a)-7(e), there is shown in more detail the gasket membrane 108. The gasket membrane 108 comprises a plurality of apertures 700 that are arranged in eight columns 702 of sixteen apertures 700 and sixteen rows 704 of eight apertures 700 on a waterproof sheet 706. Referring specifically to Fig. 7(e) it can be seen that each aperture 700 comprises an upper annular collar 708 and a lower annular collar 710 which extend around the circumferential edge of the aperture on the upper face 712 of the gasket membrane 108 and around the circumferential edge of the aperture on the lower face 714 of the gasket membrane 108 respectively. The upper annular collar 708 and the lower annular collar 710 are used to enhance the waterproof seal formed by the gasket membrane in the highway electronic display 100.

[0035] With reference to Figs. 8(a)-8(c), there is shown in more detail the display cover 110. The display cover 110 comprises a plurality of apertures 800 arranged in a series of eight columns 802 of sixteen apertures 800 and sixteen rows 804 of eight apertures 800.

[0036] Referring to Figs. 9(a)-9(c), there is shown in more detail the optical element 600. The optical element 600 is made of transparent material such as plastics or glass and comprises a convex boss 608 and a cylinder 610. The optical element 600 is moulded from a unitary piece of material to form a continuous piece with the baseboard 606. The rear face of the baseboard 606 comprises the convex bosses 608 that are used to converge and concentrate light from the LEDs 112. The front face of the baseboard 606 comprises the cylinders 610 that protrude outwardly from the baseboard 606 and which terminate in a diffusing lens 900

[0037] The diffusing lens 900 of the cylinder 610 comprises a curved surface that diffuses the concentrated light from the LEDs 112 into a widened beam (not shown). This widened beam is directed into a desired viewing region for motorists so that the alphanumeric message or symbol on the highway electronic display 100 may be seen by motorists when viewing the highway electronic display 100 from an angle. The diffusing lens 900 of the cylinder 610 is curved laterally across the highway electronic display 100. This curve will spread and diffuse the light to the left and right of the highway electronic display in a triangular shaped viewing region.

[0038] The diffusing lens 900 of the cylinder 610 is also downwardly inclined to minimise the amount of incident light from the sun that enters the optics plate as the inclined surface 902 will require the sun to be at a lower position in the sky to refract light through the optics plate 106 rather than reflect the sunlight off the optics plate 106.

[0039] Throughout the preceding specification, reference has been made to the display applying to a highway sign, however it will be readily appreciated that the display can be equally well used in other general displays for motorists.

[0040] It will be further understood that any light source may be used in place of the LEDs 112 provided that the light source provides sufficient illumination to meet the requirements of the relevant standards. Typically, a highway display must be ten time brighter when the LEDs are switched on in comparison to when the LEDs are switched off and sunlight is shining on the LEDs and optics stage of the highway sign.

[0041] The optics plate 106 has been described with reference to two distinct colours 612, 614, however, any number of different colours may be used, and the optics plate 106 is not limited to just using red and orange as colours. It will also be understood that one of the colours may be colourless, in effect a see-through material. Two differently coloured strips may be used with a plurality of LEDs that are all the same colours, provided that two different coloured light beams are emitted from horizontally adjacent LEDs in a column.

[0042] In assembly, the electronic display 100 is made up by connecting the PCB 102 to the alignment plate 104, which is in turn connected to the optics plate 106. The gasket membrane 108 overlays the baseboard 606 of the optics plate 106 and surrounds the optical elements 600. The display cover 110 is then finally placed on top of the gasket membrane 108. The PCB 102, the alignment plate 104, the optics plate 106, the gasket membrane 108 and the display cover 110 are all fixedly held together by screws and complementary threads. Alternatively latches, clips or any complementary inter-engaging fixing means may be used. In assembly, the LEDs 112 on the PCB 102 will each protrude slightly into the larger mouth 506 of the through holes 500 on the alignment plate 104. In a preferred embodiment, the convex bosses 608 on the optics plate 106 will not protrude into the exit holes 508 of the through holes 500 as the optics plate 106 may be held apart from the alignment plate 104 by spacers (not shown). The annular collars 708 of the gasket membrane 108 will abut against the edges of the apertures 800 on the display cover 110, and, the annular collars 710 of the gasket membrane 108 will abut against ringed portions of the baseboard 606 that surround the cylinders 810 of the optics plate 106 creating a substantially watertight fit.

[0043] In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms "include, includes, included and including" or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation.

[0044] The invention is not limited to the embodiments hereinbefore described which may be varied in both construction and detail with the scope of the appended claims.

Claims

1. A highway electronic display comprising a printed circuit board (PCB) having a plurality of light emitting diodes (LEDs) mounted thereon arranged in rows and columns, an optics stage, and a display cover, characterised in that the optics stage comprises an alignment plate and an optics plate, the alignment plate comprising a sheet of opaque material positioned intermediate the PCB and the optics plate and having a plurality of through holes arranged in rows and columns coincident with the rows and columns of the LEDs, and in which the optics plate comprises a sheet of transparent material having a plurality of optical elements arranged in rows and columns coincident with the rows and columns of the LEDs, each optical element comprising a convex boss protruding outwardly from a rear face of the optics plate proximal the LEDs and a cylinder terminating in a diffusing lens protruding outwardly from a front face of the optics plate distal from the LEDs, the convex boss concentrating light emitted from an LED through the cylinder and the diffusing lens re-directing that light into a desired beam, each optical element formed in a single, unitary piece with the sheet of transparent material.

2. A highway electronic display as claimed in claim 1, wherein the plurality of LEDs comprise LEDs of two distinct colours, each LED along a row on the PCB being of one distinct colour and each LED along an adjacent row on the PCB being of the other distinct colour such that the PCB comprises alternating rows of coloured LEDs, and, the sheet of transparent material of the optics plate also comprising alternating rows of two distinct coloured transparent materials which correspond to the alternating rows of coloured LEDs on the PCB.

3. A highway electronic display as claimed in claim 2, wherein a pair of adjacent LEDs in a column on the PCB form a pixel of the highway electronic display, each pixel therefore containing an LED of the two distinct colours.

4. A highway electronic display as claimed in any preceding claim, wherein the diffusing lens comprises a roughened outer surface.

5. A highway electronic display as claimed in any preceding claim, wherein the diffusing lens comprises a translucent outer surface.

6. A highway electronic display as claimed in any preceding claim, wherein the diffusing lens comprises a curved outer surface.

7. A highway electronic display as claimed in any preceding claim, wherein the diffusing lens comprises a downwardly inclined outer surface.

8. A highway electronic display as claimed in any preceding claim, wherein the through holes of the alignment plate are substantially frusto conical in shape terminating in a tubular collar, whereby the through holes taper from the rear of the alignment plate to the front of the alignment plate.

9. A highway electronic display as claimed in claim 8, wherein the alignment plate is held spaced apart from the PCB so that a tip of each of the LEDs mounted on the PCB enters an open mouth of each of the through holes on the alignment plate.

10. A highway electronic display as claimed in any preceding claim, wherein a gasket membrane is positioned intermediate the optics plate and the display cover.

11. A highway electronic display as claimed in claim 10, wherein the gasket membrane comprises a plurality of apertures in rows and columns coincident with the rows and columns of LEDs on the PCB.

12. A highway electronic display as claimed in claim 10, wherein each aperture is surrounded by an upstanding annular collar.

13. A highway electronic display as claimed in any preceding claim, wherein the display plate comprises a plurality of apertures in rows and columns coincident with the rows and columns of LEDs on the PCB.

Drawing