EP2929523A1

EP2929523A1 - Display unit for modular message board

Info

Publication number: EP2929523A1
Application number: EP12798703.0A
Authority: EP
Inventors: Martin KRUMMENERL; Daniel LLINAS
Original assignee: Swarco Futurit Verkehrssignalsysteme Ges mbH; Swarco Futurit Verkehrssignalsysteme GmbH
Current assignee: Swarco Futurit Verkehrssignalsysteme Ges mbH; Swarco Futurit Verkehrssignalsysteme GmbH
Priority date: 2012-12-05
Filing date: 2012-12-05
Publication date: 2015-10-14
Also published as: WO2014086408A1

Abstract

A display unit (1) of the type having a circuit board (5) with numerous illuminants (6) arranged in a matrix pattern on its front side, which illuminants are connected to a control unit controlling the illuminants (6) individually or in groups has a light discharge member (21) forming the display side of the unit (1). This member (21) is arranged with a distance to the light emitting side of the illuminants (6), which light discharge member (21) comprises optical elements (22) arranged in a matrix pattern. Each optical element (22) is arranged to receive light emitted from at least one illuminant (6) and route it through the light discharge member (21) to be radiated from the display side of the unit. The light discharge member (21) is manufactured in one piece comprising its optical elements (22) and structural elements linking the optical elements (22) in a fixed arrangement to each other, whereas on the light radiating side of the light discharge member (21) a mask (23) is disposed, leaving openings for the radiation of light being discharged from the optical elements. The mask (23) is designed to block ambient light to pass through the mask into the light discharge member (21). With distance to the back-side of the light discharge member 21 a support board (17) is secured, holding in place the outlet ends of optical guides (7) arranged between the circuit board (5) and the support board (17). Each optical guide (7) collects the light of at least one illuminant (6) and guides the light towards an optical element (22) of the light discharge member (21), whereas the outlet end of such optical guide (7) is spaced from the optical element (22), to which the exiting light of this optical guide (7) is to be routed.

Description

Display unit for modular message board

The invention is directed to a display unit of the type having a circuit board with numerous illuminants arranged in a matrix pattern on its front side, which illuminants are connected to a control unit controlling the illuminants individually or in groups and having a light discharge member forming the display side of the unit arranged with a distance to the light emitting side of the illuminants, which light discharge member comprises optical elements arranged in a matrix pattern, each optical element arranged to receive light emitted from at least one illuminant and route it through the light discharge member to be radiated from the display side of the unit.

Display units of this kind are typically used to build-up modular changeable information sign or message boards, for example to be used for traffic information and/or signalling. Such display unit may, of course, also be used as a stand-alone unit. Such display unit shows on its display side a matrix pattern of light radiating elements. In order to display an information, for example, a word or a graphic (for instance a pictogram) light is emitted from those light radiating elements that the word or the graphic representation may be seen. Such display unit has a circuit board carrying in a matrix pattern numerous illuminants, typically LEDs on its front side facing to the display side of the display unit. The circuit board is arranged with a distance behind a light discharge member, which resembles with its front side the display side of the unit. According to one prior art between the light discharge member is translucent. Between the light discharge member and the circuit board a spacer is arranged, which spacer is of light blocking nature. Within such spacer a plurality of LED holes are formed to allow each LED to extend into the spacer and transmit light through the spacer and the translucent light discharge member.

The LEDs on the circuit board are controlled by a control unit allowing individual addressing of the LEDs. This enables to display changeable information and messages respectively on the display side of the display unit. A display unit as described above and to be used in a modular changeable information sign system is disclosed in EP 0 894 317 B1 . In case such display units are to be used for traffic control these need to meet high standards; for example: information and/or messages displayed on the display side of such display unit, need to be recognized even if ambient light, in particular sunlight, is illuminating the display side of the unit. Further, such units need to be weather-proof, in particular water-proof.

In order to enhance the intensity of the light radiated from the display side of such unit, it has been suggested to use lenses secured in the light discharge member. The lenses are arranged within the light discharge member in a matrix pattern, which is identical to the matrix pattern of the illumi- nants on the circuit board. The light discharge member, typically an aluminum plate with openings arranged in the matrix pattern of the illuminants, carries the lenses. According to one prior art the lenses are secured in the openings by using a sealing compound. Instead of using a sealing compound to secure the lenses in the openings of the light discharge member, in WO 2004/068447 A it has been suggested to provide a tube-like housing of plastic material for each lens, which housing is inserted with the lens into an opening of the light discharge member and is secured therein in sealed arrangement to the inside walls of the openings of the plate. It has further been suggested, that to route the light emitted from an illuminant to the lens, an optical guide is used. Such optical guide is arranged to collect the light emitted from an LED and route it towards the lens. The lens may be part of the optical guide. Then, the outlet side end of this optical element is shaped in the form of a convex lens. To provide for the sealed arrangement of such tube-like housing within an opening of the plate, the outside wall of such tube carries retentions.

Although when using optical elements, the light intensity of the information displayed on the display side of the display unit may be enhanced compared to units not using lenses since light is cumulated, still the effort needed for the assembly such unit is quite high. Further, it would be appreciated, if the quality of the information displayed on the display unit could be further optimized.

In the light of the prior art sketched-out above, it is an object of the invention to provide a display unit of the kind referenced to in the first para- graph, which addresses these requirements.

The technical problem sketched-out above is solved by way of a display unit with the features of the preamble of claim 1 , in that the light discharge member is manufactured in one piece comprising its optical elements and structural elements linking the optical elements in a fixed arrangement to each other, whereas on the light radiating side of the light discharge member a mask is disposed, leaving openings for the radiation of light being discharged from the optical elements, which mask is designed to block ambient light to pass through the mask into the light discharge member, and in that with a distance to the backside of the light discharge member a support board is secured, holding in place the outlet ends of optical guides arranged between the circuit board and the support board, each optical guide collecting the light of at least one illuminant and guiding the light towards an optical element of the light discharge member, whereas the outlet end of such optical guide is spaced from the optical element, to which the exiting light of this optical guide is to be routed.

According to this concept, the light discharge member of the unit is manufactured as a one-piece component comprising the optical elements and the structural links connecting the optical elements defining their place and arrangement to each other. Typically, the structural links will be designed to be a plate, with which the complete interspace between the optical elements is closed. This one-piece component is due to the optical characteristics needed for the optical elements manufactured from a translucent material. This light discharge member disposes of a mask shielding the interspace between the optical elements from ambient light, for example sunlight, to pass through the parts of the transparent component forming the fixed links between the optical elements. Such mask is according to a preferred embodiment a coating on the display side of the light discharge member capable to block ambient light and to minimize reflections on the display side surface. Such coating may comprise a coat of black rubber or rubber-kind material, on which black flock material is applied.

Further, spaced from the backside of the light discharge member, a support board is secured. In a preferred embodiment, the support board is secured to the light discharge member. The support board holds in place the outlet end of the optical guides arranged between the circuit board and the support board. Each optical guide collects the light of at least one illu- minant and guides the light towards an optical element. The outlet end face of such optical guide is in alignment with an optical element of the light discharge plate. The outlet side end faces of the optical guides are held by the support board in a distance to the optical element of the light discharge member, to which the light exiting of this optical guide is radiated. The support board typically is of the kind to block light from entering or exiting the interspace between the circuit board and the support board. Light may only pass the support board by way of the optical guides. Therefore, in the direction of light emission from the illuminants to the optical elements, each optical element is only charged with the light of the one or more optical guides, intended to charge such optical element. On the other hand, the support board with its light blocking characteristics hinders light to further enter into the display unit. Although the mask arranged on the front side of the light discharge member is light blocking, the support board ensures, that ambient light, in particular sunlight shining through the optical elements into the unit, does not reach the illuminants on the circuit board. The distance of the ends of the optical guides to the backside of the optical elements is provided in such a manner, that the requirements traffic sign and message boards need to meet in respect of ambient light shining on the display side of the optical elements with an angle and is not coupled into the outlet side face of the optical guides are met.

The advantages of this concept are numerous. Manufacturing the light discharge member with the optical elements and its fixed links facilitates the assemblage of such display unit. Further, in an embodiment, in which the fixed links completely fill the interspace between the optical elements, there is no need to provide for further sealing measures. It is then only needed to provide for a sealed arrangement between the light discharge member and a housing or some other member adjacent to the light discharge member. Such sealing, though, is a usual measure, which is necessary in prior art display units.

Still further, providing a light discharge member manufactured in one piece with its optical elements, which light discharge member typically is a member manufactured from a plastic compound, allows to provide the light dis- charge member with adapter members such as mounting aids protruding from the backside of the light discharge member. Such adapters may be of the kind of a pin, each providing an abutment flange, for example by forming a recess, on which the surface facing to the light discharge member of the support board rests. Providing the light discharge member with such adapters ensures mounting of the support board with a minimum of tolerances with respect to its positioning to the light discharge member, which in turn ensures, that the outlet face of the optical guides held by the support board are in the intended alignment with the entrance side of the optical elements of the light discharge member. Thus, light being radiated from each optical element will exit each optical element in the prescribed manner giving each optical element its intended visual appearance.

These holding adapters may also be formed with two recesses, thus providing two abutment flanges spaced apart from each other. With such embodiment on the abutment flange being closer to the light discharge member, the support board rests. On the other abutment flange, it is possible to fasten the circuit board. With such embodiment the holding adapters are in charge to define the distance of the support board to the light discharge member and the distance of the circuit board from the support board. Such measure, if taken, may further facilitate the assembly of such display unit. In order to hold the support board in place with its surface facing the light discharge member after mounting the support board on such holding adapter, a bushing is placed on the section of the holding adapter before the circuit board is mounted. The bushing is designed to contact the backside of the support board and the front side of the circuit board thus defining the distance of these two boards.

In a preferred embodiment, the outlet side face of the optical guides is arranged flush with the surface of the support board facing to the light discharge member. This ensures, that a maximum of light exiting such optical guide is radiated to the located optical element and also that no light may be coupled into the optical guide from a part of a side face.

In a preferred embodiment, the optical guides are manufactured by way of optical guide members, each member comprising several optical guides arranged parallel in a row with each other and fixedly linked to one an- other. Such optical guide members comprise spacers. The spacers are used to hold the optical guides in place between the support board and the circuit board. The spacers therefore have an abutment surface at each of their ends, each surface resting either on the surface of the circuit board facing the support board or on the surface of the support board facing the circuit board respectively. This allows an arrangement of the optical guides being held with their outlet side end within the support board and with their inlet side board very close to the light emitting surface of the illuminant. The optical guides may contact the illuminant surface with their inlet side face. In order to hold the optical guide members in place without any further measures, according to one embodiment, some of the spacers, preferably all of them, are provided with pin-like extensions protruding from their abutment surfaces and extending into holding holes of the circuit board and the support board respectively. It will be easily understood, that mounting the optical guides arranged in such optical guide members and with such spacers is easily undertaken, with the mounting positions being well-defined.

The components of the display unit may be held together by way of one or more fasteners.

Typically such unit will be arranged in a weather-proof housing, with which the light discharge member along its periphery will be sealed with. It is also possible to arrange two or more of such display units in one common housing. With such embodiment one controller may be used for controlling the illuminants of the individual display units. The same accounts to the power supply. Arranging more than one display units to be controlled by one controller, also allows for a better energy saving mode of operation. It is then possible to completely shut-down those units, from which no information or message or part thereof is to be displayed.

The optical elements as part of the light discharge member will typically have a geometry of a convex lens. The illuminants on the circuit board are according to one embodiment LEDs, whereas it is well possible to use more than one LED as one illuminant, in particular, if each of these LEDs emits light in a different colour (wavelength). In one such embodiment, each illuminant may comprise three LEDs, one of which will emit green light, one of which will emit red light, and one of which will emit blue light. Instead of using full colour illuminants as described above it is also possible to use full colour illuminants, comprising one light emitting device capable of emitting light in the desired wavelength. Of course, instead of LEDs, any other appropriate illuminant may be used.

The invention will in the following be described by way of a specific embodiment with reference to the figures. The figures show:

Fig. 1 : perspective view of an arrangement of several display units arranged as part of a message board,

Fig. 2: a perspective cross-sectional view of one of the display units of figure 1 ,

Fig. 3: an enlarged side elevational view of a part of the cross-section of figure 2,

Fig. 4: a cross-sectional view of part of the display unit of figure 2 in another plane section, and

Fig. 5: a backside view of part of the message board of figure 1 .

A display unit 1 to be used for displaying information for guiding traffic is sketched in figure 1 as part of such message board. The message board depicted comprises numerous display units 1 . Figure 1 shows part of the message board with an assembly of four display units 1 . The display units 1 are all identical and are arranged on support beams 2 to be held together. Each display unit 1 is housed a housing 3. The front side 4 of the housing 3 is the display side of each display unit 1 .

In the following, one of the display units 1 is described in more detail with reference to figures 2 to 4. Such display unit 1 comprises within its housing 3 a circuit board 5, carrying numerous LEDs as illuminants. The LEDs marked with reference numeral 6 are of the RGB-kind. This means, that one illuminant is made up of three LEDs, one of which emits red light, one of which emits green light and one of which emits blue light. With such LED arrangement it is possible to emit light in different colours. The LEDs 6 are arranged on the circuit board 5 according to a matrix pattern. In the present embodiment, on the circuit board 5 the matrix pattern is made up of 16 x 16 RGB-LEDs 6. The circuit board 5 further carries electric/electronic equipment needed to run the display unit 1 . Arranged in front of the light emitting face of each LED 6, an optical guide 7 is arranged. The inlet side 8 of such optical guide 7 is arranged to collect the light emitted from one LED 6. Preferably the inlet side face 8 of the optical guides 7 are in contact with the light emitting surface of the LEDs 6. In the present embodiment, a number of optical guides 7 are grouped together to be one assembly component. In the present case, eight optical guides 7 make one such mounting element, which is referenced to as optical guide member. The optical guides 7 in such optical guide member are arranged parallel to each other and are interlinked with each other by structural links 9. The optical guides 7 are arranged in a row with distance to each other, which distance is defined by the structural links 9. Intersected within some of the structural links 9, spacers 10 are arranged. The spacers 10, the structural links 9 and the optical guides 7 are manufactured in one piece from a plastic compound resulting in a translucent body. Thus, all these elements are not only easily manufactured. Also assembly is facilitated. It will be understood, that the number of optical guides grouped into such optical guide member 1 1 , may be different to the embodiment depicted, which is to be understood only as an example. In the depicted embodiment two optical guide members 1 1 are needed to build one complete row of optical guides.

The spacers 10 are used to define the mounting position of such optical guide member 1 1 on the circuit board 5. In order to achieve this, each spacer 10 has a mounting pin 12 protruding from its end face facing the circuit board 5. The mounting pins 12 of the spacers 10 are inserted into mounting holes 13 of the circuit board 5. The end face of the spacers 10 facing to the circuit board 5, are designed to have an abutment surface 14, which is worked in the present embodiment by an abutment flange. The abutment surface 14 is intended to contact the surface of the circuit board 5. The spacers 10 are designed with their other end in the same manner, thus also providing an abutment surface 15 and a mounting pin 16. Arranged with a certain distance in front of the circuit board 5 is a support board 17. The support board 17 has light blocking characteristics. In the present embodiment, the support board 17 is manufactured from black plastic. The support board 17 shows openings 18 to receive the outlet side ends of the optical guides 7. The support board 17 has mounting holes 19, into which the mounting pins 16 of the spacers 10 protrude. The abutment surface 15 of the spacers 10 is in contact with the backside of the support board 17 - the face of it facing the circuit board 5. Therefore, the spacers 10 also define the distance between the circuit board 5 and the support plate 17. The outlet side end faces of the optical guides 7 are arranged within the openings 18 of the support plate 17 in that their outlet side face is in a flush arrangement with the front side surface 20 of the support board 17.

Arranged with a distance to the front side surface 20 of the support plate 17 is a light discharge member 21 , which in the present case is a light discharge plate. The light discharge plate 21 comprises in the same matrix pattern arrangement as the LEDs 6 on the circuit board 5 lenses 22 as optical elements. The lenses 22 show convex optical characteristics. All lenses 22 of the light discharge plate 21 are fixedly linked with each other to be a light discharge plate manufactured in one piece from a plastic compound resulting in a translucent plastic body. The front side of the light discharge plate 21 is covered by a mask 23 leaving only the contours of the lenses 22 uncovered. The mask 23 is of the kind using a rubber base with flock applied to the outside. The colour of the mask 23 is black. The mask 23 is applied as a coating on the front side of the light discharge plate 21 . The mask 23 is intended that no ambient light will pass through the light discharge plate 21 into the display unit 1 . Further, the outer surface of the mask 23 is designed with its flock to omit reflections from ambient light on the front side 4 of the display unit 1 .

The support plate 17 is arranged with a distance to the light discharge plate 21 in a manner, that ambient light, for example sunlight, coming through the lenses 22 in a certain angle are not coupled into the optical guides 7.

An enlarged cross-sectional view of a section of the display unit 1 is seen in figure 3. Figure 3 shows, that the cross-sectional area of the optical guides 7 increases from its inlet side face 8 to its outlet side face 24. Further, this figure shows the flush arrangement of the outlet side face 24 of the optical guides 7 with the front side 20 of the support board 17.

Formed on the backside of the light discharge plate 21 are a couple of holding adapters 25, one of which is to be seen in figures 3 and 4. The holding adapters 25 are designed as spacers to define the distance between the support board 17 and the light discharge plate 21 . Figure 4 shows in a schematic cross-sectional view in a sectional plane through such holding adapter 25. The holding adapter 25 has in its front part a recessed section 26 forming an abutment flange 27. The support board 17 is provided with mounting openings 28, into which the recessed section 26 of a holding adapter 25 is introduced with the abutment flange 27, to be in contact with the front side surface 20 of the support board 17. Into the front faces of the holding adapters 25, longitudinal holes are used to introduce a blind rivet 29 of plastic material. Such blind rivet 29 is used to secure a screw element 30, which screw element 30 has a threaded opening 31 on its side facing to the circuit board 5. A screw with its head resting on the backside of the circuit board 5 is used to fasten the circuit board 5 to the screw elements 30 with its threaded shaft being screwed into the threaded opening 31 . Since the screw elements 30 are secured to the light discharge plate 21 , the sandwich structure of the display unit 1 comprising the light discharge plate 21 , the structural board 17 and the circuit board 5 with the optical guide members 1 1 in between the structural board 17 and the circuit board 5 may securely be fastened to each other. This unit, when assembled, will be introduced into the housing 3.

The housing 3 in the depicted embodiment is used to house two display units 1 described above. Both display units 1 are linked together with one common power supply unit 32 and one control unit 33. Figure 5 shows the backside of this assembly with the lid covering the power supply unit 32 and the control unit 33 on the backside of the housing 3 being demounted.

The invention is described in the foregoing by way of an example. It will be apparent for a person skilled in the art, that there are other ways to work the invention as claimed. Reference numerals

display unit

structural beam

housing

front side

circuit board

LED

optical guide

inlet side face

structural link

spacer

optical guide member

mounting pin

mounting hole

abutment surface

mounting pin

support board

opening

mounting hole

front side surface

light discharge plate

lens

mask

outlet side face

holding adapter

recessed section

mounting opening

blind rivet

screw element

opening

power supply unit

control unit

Claims

Display unit of the type having a circuit board (5) with numerous illuminants (6) arranged in a matrix pattern on its front side, which il- luminants (6) are connected to a control unit controlling the illuminants (6) individually or in groups and having a light discharge member (21 ) forming the display side of the unit (1 ) arranged with a distance to the light emitting side of the illuminants (6), which light discharge member (21 ) comprises optical elements (22) arranged in a matrix pattern, each optical element (22) arranged to receive light emitted from at least one illuminant (6) and route it through the light discharge member (21 ) to be radiated from the display side of the unit (1 ), characterized in, that the light discharge member (21 ) is manufactured in one piece comprising its optical elements (22) and structural elements (22) linking the optical elements in a fixed arrangement to each other, whereas on the light radiating side of the light discharge member (21 ) a mask (23) is disposed, leaving openings for the radiation of light being discharged from the optical elements (22), which mask (23) is designed to block ambient light to pass through the mask (23) into the light discharge member (21 ), and in that with a distance to the backside of the light discharge member (21 ) a support board (17) is secured, holding in place the outlet ends of optical guides (7) arranged between the circuit board (5) and the support board (17), each optical guide (7) collecting the light of at least one illuminant (6) and guiding the light towards an optical element (22) of the light discharge member (21 ), whereas the outlet end of such optical guide (7) is spaced from the optical element (22), to which the exiting light of this optical guide (7) is to be routed.

Display unit according to claim 1 , characterized in, that the light discharge member (21 ) is a plate with its optical elements (22) being integrated within the plane of this plate.

Display unit according to claims 1 or 2, characterized in, that formed on the surface of the light discharge member (21 ) facing to the support board (17), a number of holding adapters (25) formed with an abutment flange (27) are arranged in a manner protruding from the backside of the light discharge member (21 ), whereas the distance of the abutment flanges (27) to the backside of the light discharge member (21 ) defines the distance of the support board (17) to the light discharge member (21 ), and in that the support board (17) has openings (28) each to receive a holding adapter (25) abutting with its abutment flange (27) on the front side (20) of the support board (17).

Display unit according to one of claims 1 to 3, characterized in, that the support board (17) is of light blocking nature.

Display unit according to one of claims 1 to 4, characterized in, that the support board (17) has openings (18), into which the outlet side ends of the optical guides (7) extend.

Display unit according to claim 5, characterized in, that the outlet side end faces (24) of the optical guides (7) are arranged to be flush with the surface (20) of the support plate (17) facing towards the light discharge member (21 ).

Display unit according to one of claims 1 to 6, characterized in, that optical guides (7) of the display unit (1 ) are grouped into optical guide members (1 1 ), each optical guide member comprising several optical guides (7) arranged in a row spaced from each other and connected to each other by a fixed link (9) and further comprising one or more spacers (10) extending between the circuit board (5) and the support board (17) each spacer (10) having at each of its end at least a support surface (14, 15) to come into contact with the surface of the circuit board (5) and the support board (17) respectively, defining the distance of the circuit board (5) from the support board (17).

Display unit according to one of claims 1 to 7, characterized in, that the matrix pattern of the illuminants (6) on the circuit board (5) and the matrix pattern of the optical elements (22) of the light dis- charge member (21 ) are identical and in that the light emitted from each illuminant (6) is guided through an individual optical guide (7) to one optical element (22).

9. Display unit according to one of claims 1 to 8, characterized in, that the optical elements of the light discharge member are lenses (22), in particular convex formed lenses.

10. Display unit according to one of claims 1 to 9, characterized in, that each illuminant (6) comprises at least two individual illuminants emitting light in a different wavelength.

11. Display unit according to one of claims 1 to 10, characterized in, that the illuminants are LEDs (6).

12. Display unit according to one of claims 1 to 1 1 , characterized in, that the display unit (1 ) is arranged in a housing (3) enclosing the sides and the backside of the unit, whereas the light discharge member (21 ) is connected to the housing (3) in a sealing arrange- ment.

13. Display unit according to one of claims 1 to 12, characterized in, that two or more display units (1 ) are housed in one housing (3).