Modular sealed luminaire

Abstract

A modular set for realising a luminaire, the set comprising a tubular housing extending along its tube axis, a gear tray, a light module, at least two end caps and an optical element having a plate-like shape being attached to the inner side of the tubular housing. The optical element comprising a first plate section consisting of a first material and a second plate section consisting of a second material, the first material being less light transmissive than the second material. The first and second plate sections each having a thickness forming at least partially the thickness of the optical element and both extending along an overlapping section, wherein a ratio between the portion of the thickness of the optical element being formed by the first plate section and the portion being formed by the second plate section decreases along the upwards vertical direction.

Description

[0001] Modular sealed luminaire

[0002] The invention refers to a modular set for reali zing a luminaire as well as to a luminaire reali zed by such set as well as to a method for reali zing a luminaire .

[0003] A modular set for reali zing a luminaire to which the preamble of claim 1 and accordingly the invention refers comprises a tubular housing extending along its tube axis over a length in a longitudinal direction, a gear tray, a light module and at least two end caps . Such modular set is configured for reali zing a luminaire by arranging the gear tray with the light module fixed to the gear tray inside the tubular housing and by closing the tubular housing at its longitudinal ends by said two end caps . The tubular housing commonly has a length in the longitudinal direction which amounts to at least twice , in particular at least five times of its length in any direction being perpendicular to the longitudinal direction . Preferably, the same is true for the gear tray . The longitudinal direction is the direction which is parallel to the tube axis of the tubular housing . As the tubular housing is designed like a tube , it encloses an interior space with its inner side all around the tube axis . The tubular housing may be formed of one piece or of several pieces , but in any case is formed tube-like thereby surrounding the interior space around the tube axis . In particular, the tubular housing in particular has an identical cross-section along at least 70 % , in particular at least 80 % , in particular at least 90 % of its length along its tube axis . The cross-section may be , e . g . , round, in particular circular, or rectangular, in particular in the form of a square . The tubular housing being formed like a tube accordingly is open at its longitudinal ends , such that the gear tray with the light module can easily be installed inside the tubular housing and can be connected by power lines extending from the interior space to the outside of the tubular housing, i . e . to the surroundings of the tubular housing . Such modular set is appropriate for easy manufacturing a luminaire which has a sealed interior space . Such interior space of the luminaire is defined by the mentioned inner side of the tubular housing as well as the end caps , i . e . the inner side of the end caps which in the luminaire are situated adj acent to the inner side of the tubular housing, such that the inner side of the tubular housing and the inner sides of the end caps together enclose the interior space . The sealing connection of the end caps to the tubular housing is a connection which inhibits entrance of undesired medium into the interior space . E . g . , the sealing may refer to a sealing as defined by IP-codes defined in IEC60529 . In the present application, the definition of sealed connection, respectively sealed interior space refers to a sealing at least according to IP20 , in particular at least according to IP50 , in particular at least according to IP54 , in particular at least according to IP66 , wherein in particularly advantageous embodiments it may also refer to a gas tight sealing such that N2 gas surrounding entirely the luminaire reali zed by the set cannot enter the interior space through the tubular housing, respectively the end caps , respectively the connection between the tubular housing and the end caps provided that the interior space of the luminaire is filled with air under the same pressure under which the N2 gas is arranged all around the luminaire . When a luminaire is reali zed by such modular set , the components of the modular set are arranged relative to each other, in particular fixed to each other, in a determined manner, such that the set with the particular arrangement of its components is in a particular operating state which refers to the particular arrangement of the components of the sets . Commonly the gear tray comprises a mounting panel with a top side and a bottom side , wherein, in any operating state of the set , the gear tray is arranged within the interior space of the luminaire , the light module being attached to the bottom side of the mounting panel . Top and bottom sides refer to sides being directed along the vertical direction, such that top and bottom side provide opposite vertical ends , wherein the vertical direction is perpendicular to the longitudinal direction . In any operating state , the light module being attached to the bottom side of the mounting panel is configured to emit light , wherein this light emanating from the light module is emitted to surroundings of the luminaire from the tubular housing with a luminous flux . The luminous flux is a unit well known in photometry which indicates the overall power of light emitted by a light source which is perceived by human eye . Accordingly, in any operating state , the luminous flux to which is referred is the overall light intensity emanating from the light module and emitted by the tubular housing surrounding the interior space as illustrated above , i . e . the luminous flux which is emitted by the outer surface of the tubular housing . Preferably, apart from commonly negligible losses of light inside the tubular housing, all of the light emitted by the light module is emitted to the surroundings of the luminaire by the tubular housing . In order to provide an appropriate emission of light from the outer side of the luminaire , it is known to provide the tubular housing with fixing means at its inner side, such that the tubular housing comprises these fixing means, wherein in the operating state the gear tray is fixed to the fixing means of the tubular housing such that the bottom side of the mounting panel of the gear tray is arranged at a vertical distance from a bottom end of the inner side of the tubular housing.

[0004] Known modular sets in principle are appropriate for realizing a luminaire. However, there is a strong need for providing luminaires which can be adapted easily to the specific requirements of specific fields of application and which can be realized cost-ef f iciently and with appropriate features for the respective field of application. Such field of application can be, e.g., illumination of offices, floors, factory buildings or shops. Since each field of application has quite different requirements concerning the desired illumination, commonly known sets comprise a large variety of different housings, different gear trays, different light modules and different optical elements to be arranged around the light module such that for each application a choice is made between the plurality of different components, and combination of these components is made for realizing a luminaire. This, however, results on the one hand in high manufacturing costs and on the other hand makes it necessary for companies to buy different types of luminaires varying remarkably in their properties, in particular in their design and functional elements. This leads to high costs for the installation and maintenance of illumination means in companies and in addition inevitably results in a potpourri of luminaires throughout the entire company which is disadvantageous in various regards, in particular with regard to a common optical design throughout the company and a common technical equipment throughout the company for simpli fying maintenance . Further, known luminaires , in particular those which try to address at least one of the above-mentioned tasks , have disadvantages with regard to their characteristics of light emission, in particular with regard to homogeneity of their emission appearance , as well as with regard to the mechanical properties and with regard to their usability, in particular concerning easy and durable installation .

[0005] Accordingly, the present invention faces the obj ective technical problem to provide a modular set for reali zing a luminaire , respectively a luminaire , respectively a method for reali zing a luminaire which addresses at least partially at least one of the above-mentioned disadvantages of common modular sets .

[0006] As one solution of the above-mentioned obj ective technical problem the present invention proposes a modular set with the features of claim 1 . A modular set according to the invention comprises a plurality of components which may be arranged in a particular manner which corresponds to a particular operating state of the modular set in which a luminaire is reali zed . The set comprises as components at least a tubular housing extending along its tube axis over a length in a longitudinal direction, a gear tray having a mounting panel with a top side and a bottom side , a light module and at least two end caps . In further embodiments of the invention, the modular set may also comprise further components as described below . The modular set , in some embodiments of the invention, may also comprise features which are described above with regard to the known modular sets to which the invention refers . In one operating state of the set , in which the luminaire is reali zed, each of the end caps is detachably and sealingly fixed to the tubular housing closing the longitudinal end of the tubular housing associated to the respective end cap . Further, in the operating state of the set , the gear tray is arranged within an interior space of the luminaire defined by an inner side of the tubular housing and the end caps . Further, in the operating state , the light module is attached to the bottom side of the mounting panel of the gear tray, wherein in the operating state light emanating from the light module is emitted to surroundings of the luminaire from the tubular housing with a luminous flux . Since the light module is attached to the bottom side of the mounting panel of the gear tray in the operating state , the light module in the operating state is configured to emit light vertically downwards , in particular exclusively vertically downwards , wherein in particular the main emission direction of the light module has an angle of less than 20 ° , in particular less than 10 ° with regard to the vertical direction . Generally, in the present application the indication of downwards as well as the indication of upwards both mean a direction having at least a component of direction which is parallel to the vertical direction, i . e . a vertical component , wherein any direction presently referred to as downwards as a vertical component having the opposite sign of the vertical component of any direction referred to as upwards , such that a downwards direction always has a vertical component with a negative sign and an upwards direction always has a vertical component with a positive sign, such that these components point to opposite directions along the vertical direction . Accordingly, the luminaire reali zed in the operating state of the modular set generally is configured to be mounted to a ceiling facing the ceiling with its top side and providing direct illumination of a room having this ceiling with light emanating from the light module being emitted downwards from the tubular housing . The tubular housing comprises a fixing means at its inner side , wherein in the operating state the gear tray is fixed to the fixing means of the tubular housing such that the bottom side of the mounting panel of the gear tray is arranged at a vertical distance from a bottom end of the inner side of the tubular housing . Since the fixing means is provided at the inner side of the tubular housing and since the bottom optical section is arranged below the fixing means , the fixing means by which the gear tray is held within the tubular housing does not impede the light propagation from the light module to the bottom optical section of the tubular housing . Of course , the bottom side of the mounting panel of the gear tray faces the bottom end of the inner side of the tubular housing . As the tubular housing with its inner side defines the interior space , the inner side of the tubular housing has a bottom end and a top end between which the interior space extends within the tubular housing, i . e . top end and bottom end of the inner side of the tubular housing define the vertical extension of the interior space within the tubular housing . In some embodiments , in the operating state the gear tray is fixed to the fixing means such that the bottom side of its mounting panel is arranged at a vertical distance from the bottom end of the inner side which amounts to at least 30 % of the maximum vertical extension of the interior space within the tubular housing, in particular to at least 40 % , in particular to at least 50 % of the maximum vertical extension of the interior space within the tubular housing . Due to the vertical distance provided between the bottom side of the mounting panel and the bottom end of the inner side of the tubular housing, there is enough space for directing light over a suf ficiently large distribution angle . In one embodiment , the tubular housing comprises a bottom optical section being arranged below the fixing means and forming said bottom end of the inner side of the tubular housing . In the operating state , the bottom optical section of the tubular housing surrounds at least partially the bottom side of the mounting panel . Accordingly, light emitted by the luminaire in the operating state to provide direct illumination is emitted by the bottom optical section of the tubular housing to the surroundings of the luminaire , i . e . to the outside of the luminaire , respectively the tubular housing . Since the bottom optical section surrounds at least partially the bottom side of the mounting panel , its inner side surrounds at least partially the light module , wherein the light emanating from the light module and emitted to the surroundings of the luminaire in the operating state is emitted by the outer surface of the bottom optical section of the tubular housing, the outer side , respectively outer surface of the bottom optical section facing away from the light module , such that any light emanating from the light module and being emitted to the outside by the bottom optical section must traverse the bottom optical section such that the bottom optical section influences the propagation direction of the light emanating from the light module before it is emitted by the outer side of the bottom optical section to the surroundings . The propagation direction of the light is influenced according to the shape of the bottom optical section which a skilled person chooses appropriately to provide a desired light distribution . E . g . , light may be refracted when entering the bottom optical section at its inner side and when exiting the bottom optical section at its outer side and / or light may at least partially be reflected by internal reflection within the bottom optical section . The shape of the surface of the bottom optical section is chosen to provide the desired influence on the propagation direction of the light , e . g . , a prismatic structure and / or any other appropriate lens structure or curved surface section at the inner and / or outer side of the bottom optical section may be provided . The generally preferable feature defining that the bottom optical section surrounds the bottom side of the mounting panel at least partially at least requires that the bottom optical section which provides the bottom end of the inner side of the tubular housing extends , starting from said bottom end, upwards towards the bottom side of the mounting panel , in particular by its sidewall portions defined later, such that the bottom optical portion is not j ust a plane portion extending perpendicular to the vertical direction but has a vertical extension such that it has portions which, in the vertical direction, are closer to the bottom side of the mounting panel that said bottom end . Preferably, the bottom optical section has two sidewall portions extending in the vertical direction towards the mounting panels and being spaced apart from each other in a transverse direction, which is perpendicular to the vertical direction, by a bottom portion of the bottom optical section, wherein with regard to the transverse direction the mounting panel is arranged between said sidewall portions . The bottom optical section is arranged below the fixing means , in particular extends only below the fixing means . In one embodiment , the bottom optical section being arranged below the fixing means and comprising the bottom end of the inner side of the tubular housing being arranged at a determined vertical distance from the bottom side of the mounting panel and at least partially surrounding said bottom side of the mounting panel is configured to emit at least 5 % , in particular at least 10 % , in particular at least 15 % , in particular at least 20 % of the light intensity upwards and at least 70 % , in particular at least 75 % , in particular at least 80 % of the light intensity downwards . Accordingly, according to this generally advantageous embodiment , the luminaire reali zed in the operating state is configured to provide both direct and indirect illumination, since , when mounted to a ceiling of a room, the light emitted downwards provides direct illumination and the light emitted upwards provides indirect illumination . This light emitted upwards typically is emitted to the ceiling or any other appropriate element of the room in which the luminaire is installed, and this ceiling, respectively other element being illuminated by this light serves for illumination of the room which is referred to as indirect illumination . In one embodiment , the tubular housing comprises a top section and the bottom optical section, the top section and the bottom optical section together closely surround the tube axis .

[0007] Accordingly, a cross-section of the tubular housing, referring to a cross-section perpendicular to the longitudinal direction and accordingly perpendicular to the tube axis , is formed by the top section and the bottom optical section, in particular over at least 70 % , in particular at least 80 % , in particular at least 90 % of the length of the tubular housing, in particular over the entire illumination length of the tubular housing, wherein in the operating state the tubular housing only within its illumination length is configured to emit light to its surroundings . Top section and bottom optical section accordingly together surround the tube axis preferably without any gap, accordingly closely . Preferably, the top section is formed of another material than the bottom optical section . In one embodiment , the tubular housing comprises installation means , e . g . formed as installation channels , by which it can be mounted to a ceiling, wherein these installation means are exclusively provided by the top section of the tubular housing. Such mounting device, e. g., may comprise recesses or projections provided at the outer side of the top section and / or hooks or clamps which, in the operating state, are provided at the top side of the top section which corresponds to the top side of the tubular housing. In one embodiment, the bottom optical section throughout its entire extension is formed of light transmissive material, e.g. transparent or translucent material, whereas the top section is formed of nontransparent material or at least material having different optical properties than the one out of which the bottom optical section is formed. In the present description, transmissive properties, of course, refer to visible light. The materials out of which top section and bottom optical section are formed may, e.g. differ from each other with regard to the stiffness and / or with regard to the light diffusive properties. In one embodiment, the bottom optical section is at least twice, in particular at least three times, in particular at least four times, as large as the top section. By being at least twice as large as the top section, the bottom optical section has a surface at its inner side which is at least twice as large as the surface of the top section at its inner side, such that the inner side of the tubular housing defining the interior space of the luminaire in the operating state is formed to at least two third by the bottom optical section and to not more than one third by the top section.

[0008] In one embodiment, the gear tray comprises or consists of a first section having a U-shaped cross-section including a bottom portion and two flank portions, wherein the mounting panel is formed by the bottom portion, the top side of the bottom portion being the top side of the mounting panel being framed by the flank portions and the bottom side of the bottom portion being the bottom side of the mounting panel facing away from the flank portions , wherein in particular the flank portions with their outer sides facing away from the bottom portion of the gear tray are facing the inner side of the tubular housing, in particular of the bottom optical section, and in particular are configured being reflective at their outer sides , wherein in particular at least 2 % of the light emitted by the bottom optical section to the surroundings in the operating state has been reflected at the outer sides of the flank portions of the gear tray before being emitted by the tubular housing to the surroundings .

[0009] According to one solution of the above-mentioned obj ective technical problem, the modular set comprises an optical element having a plate-like shape with two plate surfaces facing away from each other, the optical element extending with a thickness between said plate surfaces . Of course , a plate in general has a shape being defined by two plate surfaces each extending in a first and a second direction, wherein these two plate surfaces are spaced apart from each other with regard to a third direction, wherein the plate extends with its thickness along the third direction between its plate surfaces , wherein first , second and third direction are perpendicular to each other . In case of a curved plate , first and second direction may be bent , but in each point of the surface the third direction is perpendicular to first and second directions at this point . According to one embodiment of the invention, in the operating state , the optical elements is attached to the inner side of the tubular housing such that it extends in a direction, which is perpendicular to the longitudinal direction, over at least 50% , in particular at least 70% , of the extension of the tubular housing in said direction, wherein one of its plate surfaces faces the inner side of the tubular housing . Preferably, said direction is the vertical direction, such that the optical element extends vertically over at least 50% , in particular at least 70% of the height of the tubular housing . The optical element is attached with regard to the inner side of the tubular housing in such a way that it is arranged within the tubular housing as described . The optical element may be attached to the inner side of the tubular housing being in direct contact with the inner side , wherein in particular the optical element is in direct contact with the inner side of the tubular housing with at least 50% , in particular at least 70% of one of its plate surfaces , in particular with the whole extension of one of its plate surfaces . The extension of the tubular housing in a particular direction defines its length and said direction . Accordingly, the extension of the tubular housing in the vertical direction corresponds to its height , the extension in the longitudinal direction corresponds to its length . According to one solution proposed by the invention, the optical element comprises a first plate section consisting of a first material and a second plate section consisting of a second material , wherein the first material is less light transmissive than the second material . The first and second plate sections each have a thickness forming at least partially the thickness of the optical element , wherein both the first and the second plate section extend along a same overlapping section of the optical element . The overlapping section is a particular section of the optical element . The overlapping section may extends over at least 50% , in particular at least 70% of the optical element in said direction, along which the optical element extends over at least 50% , in particular at least 70% of the extension of the tubular housing . Within the overlapping section of the optical element , both the first and the second plate section extend along the plate surfaces of the optical element . The overlapping section accordingly comprises at least a portion of each of the plate surfaces of the optical element . Within the overlapping section, each of first and second plate section forms a portion of the thickness of the optical element . In one embodiment , the thickness of the optical element within the overlapping section is given by the sum of the thicknesses of first and second plate sections . First and second plate sections each may have a shape like a plate with varying thickness , such that they extend continuously along the plate surfaces within the overlapping section . Accordingly, first and second plate section extend preferably continuously in first and second direction, along which the optical element extends with its plate surfaces , wherein in a third direction, in which the optical element extends with its thickness , first and second plate section are arranged like a stack . First and second plate sections may lie against each other, wherein, e . g . , their surfaces by which they are lying against each other may in some embodiments have a non-planner contour . According to one embodiment , a ratio between the portion of the thickness of the optical element being formed by the first plate section and the portion of the thickness of the optical element being formed by the second plate section decreases along the upwards vertical direction . Accordingly, when comparing a first ratio given by the thickness of the first plate section divided by the thickness of the second plate section which these first and second plate sections have within a particular first vertical section of the overlapping section with a second ratio which is given by the thickness of the first plate section divided by the thickness of the second plate section which they have within a second vertical section of the overlapping section, wherein the second vertical section is situated above the first vertical section, the first ratio is larger than the second ratio . In particular, the ratio between the portion of the thickness of the optical element being formed by the first plate section and the portion of the thickness of the optical element being formed by the second plate section decreases continuously at least over a part of the overlapping section along the upwards vertical direction, in particular over at least 20% , in particular over at least 30% , in particular over at least 50% of the vertical extension of the overlapping section . In particular, each of the plate sections have a maximum thickness within the overlapping section of at least 0 , 5 mm, in particular at least 1 mm, in particular at least 1 , 5 mm . In particular, the optical element has a maximum thickness of at least 2 mm, in particular at least 3 mm, in particular of less than 7 mm, in particular less than 5 mm within the overlapping section . Said variation of the ratio of the thicknesses of first and second plate section provides a very easy and ef fective way to reali ze a homogeneous appearance , respectively illumination property, of a luminaire reali zed by this set . By using materials having di f ferent light transmission properties and by varying their thickness , the amount of light which passes through the optical element varies along its extension along its plate surfaces . Accordingly, a luminaire which has a light module , and in particular a direct optical element being arranged at the light module , which provides an inhomogeneous illumination of the inner side of the tubular housing can be remarkably improved by such optical element . In one embodiment , the ratio of the thickness between first and second plate section varies independence on the luminous flux which, in the operating state , reaches the optical element , such that in areas of the overlapping section in which the luminous flux is higher the ratio is higher . This may be true for at least a part of the overlapping section, in particular for at least 10% , in particular at least 20% , in particular at least 50% of the overlapping section . Preferably, the tubular housing comprises two sidewalls , each of the sidewalls delimiting the interior space at one of its transverse ends , wherein the set comprises first and second optical elements with features as presently described, wherein a first of said optical elements is attached to a portion of the inner side of the tubular housing provided by a first sidewall and the second optical element is attached to another portion of the inner side of the tubular housing being provided by a second of said sidewalls . Preferably, the tubular housing has a rectangular shape , wherein said two sidewalls extend parallel to each other along the vertical direction and wherein the optical elements each extend over at least 50% , in particular at least 70% of the height of each of said sidewalls . In particular, said two optical elements are identical .

[0010] In one embodiment , the first and second plate section each extend along at least 30% of the plate surfaces of the optical element . In one embodiment , the second plate section forms at least 80% of the thickness of the optical element in an upper section of the optical element , wherein in particular the second plate section forms at least 90% , in particular 100% of the thickness of the optical element at its upper end . In one embodiment , the first plate section forms at least 80% of the thickness of the optical element in a lower section of the optical element , wherein in particular the first plate section forms at least 90% , in particular 100% of the thickness of the optical element at its lower end . Accordingly, preferably the optical element is predominantly formed by the second plate section within an upper part of its extension and is predominantly formed by the first plate section in a lower part of its extension . Preferably, upper section and lower section each extend over at least 10% , and particular over 20% of the vertical extension, i . e . height , of the optical element , in particular upper and lower section are spaced apart from each other vertically .

[0011] In one embodiment , each one of first and second plate sections forms a portion of at least one of the plate surfaces of the optical element . In particular, each one of first and second plate sections forms a portion of both plate surfaces . In one embodiment , the first plate section forms a portion of both plate surfaces in a lower section of the optical element . In one embodiment , the second plate section forms a portion of both plate surfaces in an upper section of the optical element . In one embodiment , the optical element and each of first and second plate sections have a same cross-action along at least 70% , in particular at least 80% , in particular at least 90% of their length, in particular along their entire length . Preferably, the optical element is produced by co-extrusion process using the first and second material . Preferably, the optical element is entirely made of plastics , wherein first and second material are di f ferent plastic material . In one embodiment , the optical element is fixed to the tubular housing by a snap- fit being provided by the tubular housing, in particular by the inner side of the tubular housing . Fixation by a snap- fit allows easy installation, preferably without use of tools . Further, fixation by a snap- fit may provide a space ef ficient fixation and / or may provide a pressing force by which the optical element with one of its plate surfaces is pressed against the inner side of the housing . Preferably, the optical element is fixed to the tubular housing by a snap- fit being arranged in an upper and a lower slot of the tubular housing . Preferably, the optical element as well as upper and lower slots each have a same cross-section throughout their entire length .

[0012] According to one solution of the above-mentioned obj ective technical problem, the modular set comprises a mounting element having a first mounting section corresponding with the fixing means of the tubular housing as well as a second mounting section corresponding with the gear tray . In the operating state , the mounting element is fixed with its first mounting section to the tubular housing and is fixed with its second mounting section to the gear tray thereby fixing the gear tray to the tubular housing . Preferably, in the operating state the mounting element fixes the gear tray releasably to the tubular housing, such that the tubular housing element can be detached from the fixing means or detached from the gear tray, starting from the operating state , such that after releasing the fixation of the gear tray from the tubular housing by the fixing means the gear tray can be removed from the housing . Preferably, the fixing means in the operating state is releasably fixed with it first mounting section to the tubular housing . Preferably, in the operating state , the mounting element is fixed releasably with its second mounting section to the gear tray . Preferably, the mounting element is a separate element which can be releasably fixed to both the gear tray and a fixing means for reali zing the operating state . Generally, in the present application the definition of releasably or detachably fixed means a fixation which subsequently can be reali zed and released several times without damages . In one embodiment , the first mounting section, in the operating state , is spaced apart vertically from the bottom side of the mounting panel of the gear tray fixed to the second mounting section, in particular by at least 1 / 7 , in particular by 1 / 6 to 1 / 4 , of a maximum vertical extension of the interior space . Preferably, at least a part of the second mounting section is configured to be fixed directly to the mounting panel of the gear tray thereby providing fixation of the mounting panel of the gear tray to the mounting element , wherein preferably the first mounting section is spaced apart vertically from this part of the second mounting section by at least 1 / 7 , in particular by 1 / 6 to 1 / 4 , of a maximum vertical extension of the interior space . Said part of the second mounting section is configured to provide all alone suf ficient fixation of the mounting panel of the gear tray to the mounting element , while of course the second mounting section might comprise further parts which are configured to fix at least one further component of the gear tray which the gear tray comprises in addition to the mounting panel . The interior space , throughout its length along the longitudinal direction of course has a vertical extension, and the maximum vertical extension is the largest vertical extension throughout the length of the interior space . Preferably, the mounting element , in the operating state , vertically extends along the bottom optical section of the tubular housing, such that the bottom optical section of the tubular housing and the mounting element both extend along a same vertical section over which the interior space extends . In one embodiment , in the operating state the bottom side of the mounting panel of the gear tray to which the light module is attached is spaced apart vertically from the bottom end of the inner side of the tubular housing by at least 50 % , in particular at least 70 % of a maximum vertical extension of the interior space , wherein in particular the mounting element extends along a bottom optical section of the tubular housing . Arranging the mounting panel and accordingly the light module at such vertical distance from the bottom end of the inner side of the tubular housing provides a particular high range of flexibility with regard to the arrangement of optical means by which the light emanating from the light module can be directed .

[0013] Preferably, the mounting element has U-shaped or H-shaped form having two flanks connected by a transverse connection rod, wherein the flanks at their upper ends together from the first mounting section and at their lower ends together from at least a part of the second mounting section, in particular the above-mentioned part of the second mounting section . Being arranged at an end of a flank means arrangement at a distance of less than 20 % , in particular less than 10 % of the entire vertical extension of the flank from an absolute vertical end of the flank . The flanks extend along the vertical direction, such that the flanks provide a vertical distance between first and second mounting sections . The transverse connection rod provides suf ficient sti f fness of the mounting element . The mounting element provides a particularly advantageous modular setup, since by the mounting element the gear tray can be fixed easily and in particular releasably to the inner side of the housing with the mounting panel being vertically spaced apart from the bottom end of the inside of the tubular housing . In particular, the mounting element can be designed to be corresponding with a plurality of components of the set , e . g . corresponding to a first component of the gear tray providing the mounting panel and a second component of the gear tray providing a cable channel section of the gear tray and to a additional gear tray to be mounted vertically spaced apart from the mounting panel above the mounting panel , such that each of the components may be fixed to the tubular housing by the same mounting element . In particular, the set may comprise a plurality of separate mounting elements , each being configured as described with regard to the one mounting element , in particular each being designed identically, wherein at least two , in particular at least three , of the mounting elements of the set , in the operating state , are arranged within the interior space being spaced from each other along the longitudinal direction and both being fixed with their first mounting section to the fixing means of the tubular housing and with their second mounting section to the gear tray . Preferably, the mounting elements are spaced from each other along the longitudinal direction by at least 1 / 10 , in particular at least 1 / 5 , in particular at least 1 / 4 of the length of the tubular housing . In particular, at least two mounting elements are provided within the interior space in the operating state , wherein each of these two mounting elements is associated to one longitudinal end of the tubular housing and is spaced apart from this longitudinal end by a less than 1 / 5 , in particular less than 1 / 10 of the length of the tubular housing . Providing a plurality of separate mounting elements allows easy manufacturing of the mounting elements as well as easy assembling, respectively disassembling, of the luminaire to obtain the operating state , respectively starting from the operating state .

[0014] According to one solution of the above-mentioned obj ective technical problem, the fixing means of the tubular housing is designed in the form of two racks each being arranged at an inner side of a sidewall of the tubular housing . Both sidewalls provide a portion of the inner side of the tubular housing . Accordingly, the inner side of the sidewall forms a portion of the inner side of the tubular housing . The sidewalls are spaced apart in a transverse direction and are limiting the interior space along this transverse direction at its to transverse ends . The sidewalls may be designed as described with regard to other embodiments . Each rack proj ects with regard to a neighbored section of the sidewall , so that the mounting element can engage with each of said recks . Each rack comprises a vertical proj ection, wherein the first fixing means of the mounting element comprises two clamp-like sidearms which each engage behind the vertical proj ection of one of the recks . Accordingly, in the operating state , said vertical proj ection of each of the recks each provides a transverse limit stop for the clamplike sidearms . Accordingly, in case the tubular housing is deformed or moved rapidly resulting in a transverse relative force between the mounting element and the tubular housing, the vertical proj ections provided at each of the recks prohibits the first mounting section of the mounting element from sliding, in the transverse direction, away from one of the recks . Accordingly, preferably each clamp-like sidearm also provides a vertical proj ection engaging with the vertical protection of the respective rack, wherein, in the operating state , the vertical proj ection of the rack is closer to the transverse center of the tubular housing than the vertical proj ection of the clamp-like sidearm . Being designed like a clamp-like sidearm, the sidearm, in the operating state , is arranged vertically above and below a respective rack thereby prohibiting a vertical movement between the rack and the sidearm . In one embodiment , each rack comprises a first vertical proj ection proj ecting upwards as well as a second vertical proj ection proj ecting downwards . In the operating state , each sidearm of the mounting element engages behind each of the vertical proj ections of the respective rack . This provides an even better limit stop with regard to the transverse direction . Engaging behind, of course , refers to engagement along the transverse direction to prohibit a transverse relative movement between the sidearms and the racks . In one embodiment , each clamp-like sidearm, in the operating state , presses with a vertical force both at the upper side against the respective rack and at the lower side against the respective rack . This provides an even better fixation . In particular, the clamp-like sidearm has an upper contact surface as well as a lower contact surface , while each sidearm presses with its upper contact surface vertically against the top side of the respective rack and with its lower contact surface vertically against a bottom side of the respective rack, wherein at least one of the contact surfaces , in particular both contact surfaces have an arclike shape in order to reduce the area of the contact surface which is in contact with the rack . This allows easy installation of the mounting element inside the tubular housing by inserting the mounting element into the tubular housing along the longitudinal direction . In one embodiment , each rack extends along the transverse direction over a transverse length which is less than 10 mm, in particular less than 5 mm, in particular less than 4 mm . In one embodiment , the vertical proj ection, respectively each of the vertical proj ections , extends over a height which amounts to at least 25% of the transverse length of the rack . Thereby, without wasting too much space inside the tubular housing, a robust fixation of the mounting element can be obtained .

[0015] In one embodiment , the tubular housing has a first fastening means at each of its longitudinal ends , wherein each of the end caps has a second fastening means , the first fastening means and the second fastening means corresponding to each other to allow fastening of each of the end caps at each of the longitudinal ends of the tubular housing providing a press- fit between the end cap and the longitudinal end to which its fixed such that the end cap is pressed along a contact surface of the tubular housing against the tubular housing, wherein the contact surface surrounds the interior space at the longitudinal end of the tubular housing . Due to the press- fit which results in pressing the end cap along the contact surface which surrounds the interior space , the interior space is sealed against the surroundings of the luminaire in the operating state of the set . The contact surface in particular surrounds the interior space uninterruptedly . In one embodiment , the contact surface extends with a first surface section surrounding the interior space around the tube axis along the longitudinal direction and extends with a second surface section surrounding the interior space around the tube axis along the vertical direction, wherein the press fit is caused by a vertical force , i . e . radial force with regard to the tube axis , pressing the end cap against the tubular housing along the first surface section, and is caused by a longitudinal force pressing the end cap against the tubular housing along the second surface section . The combination of such surface sections allows easy reali zation of a good seal . Preferably, a gasket , e . g . having at least one of the features described below, is arranged between the tubular housing and the end cap along said contact surface , such that the end cap is pressed at least to a section of the contact surface , in particular to said first and / or second surface section, indirectly via the gasket against the contact surface . Such gasket , in particular made of plastics and preferably being elastic, provides an improved sealing . The set preferably comprises a plurality of identically formed gaskets , wherein in the operating state both end caps are pressed to the respective longitudinal end of the housing to which they are associated at least over a surface section of the contact surface via such gasket . Preferably, further ones of this plurality of gaskets used as the gasket for connection between tubular connection element and tubular housing and / or for connection between end cap and tubular module housing, respectively tubular housing and tubular module housing as described below . First and second fastening means are configured corresponding to each other such that they can engage with each other in order to reali ze detachable fixation with each other thereby reali zing said press- fit . In particular, the first and second fastening means are configured to be detachably fixed to each other only by relative movement to each other, such that first and second fastening means can be attached to each other without the need of further means . Preferably, first and second fastening means are configured to be detachably fixed to each other only by turning relative to each other around a rotation axis which is parallel to the longitudinal axis and thus parallel to the tube axis . In particular, the rotation axis is the tube axis . This allows particularly easy fastening and detaching of first and second fastening means . Preferably, first and second fastening means are configured as bayonet closure . Preferably, the first fastening means is arranged at an outer side portion of the tubular housing and the second fastening means are arranged at an inner side portion of the respective end cap which comprises the respective second fastening means . The arrangement of first fastening means and the outer side of the tubular housing and of second fastening means at the inner side of the end cap makes it possible that the end cap forms a longitudinal outer side portion of the luminaire in the operating state , and in this longitudinal outer side portion which may extend over a remarkable length speci fic features may be provided in the retaining sidewalls of the end cap, like a grommet or a pre-stamped cut out , which may allow access to the interior space . Accordingly, the tubular housing may be manufactured cost-ef ficient with regard to these features being present in the end cap . In particular, the tubular housing with its first fastening means may be , in the operating state , arranged within the end cap which is particularly advantageous for the outer appearance of the luminaire . Preferably, the outer side of the end cap is aligned flush with the outer side of the tubular housing at the transition from the end cap to the tubular housing in the operating state . Preferably, the first fastening means comprises a first portion which is inserted into the end cap in the operating state as well as a second portion which is pressed against a longitudinal end of the end cap in the operating state . Said second portion may be designed as flange abutting against the end cap with a pressing force which is directed along the longitudinal axis . In particular, said flange may provide said above-mentioned second surface section of the contact surface .

[0016] In one embodiment , the tubular housing comprises a tube element as well as two end elements , wherein the end elements each are connected undetachably, in particular welded or glued, to respectively one longitudinal end of the tube element . In the operating state , each of the end caps is sealingly and detachably fixed to respectively one of the end elements which is associated to the longitudinal end of the tubular housing to which the respective end cap is associated . The provision of the tube element on the one hand as well as of the two end elements on the other hand allows easy manufacturing of the tubular housing . In particular, the tube element may be manufactured by extrusion process , in particular co-extrusion process , in particular in case the top section and the bottom optical section are made of di f ferent material . Generally, the tubular housing may be manufactured of plastics . The tube element , in particular, has a continuous cross-section perpendicular to the longitudinal direction over at least 90 % of its longitudinal extension, in particular over its entire longitudinal extension . In particular, each of the end elements comprises one of the first fastening means of the tubular housing, respectively, wherein in particular each of the end elements comprises said contact surface illustrated above against which the respective end cap is pressed in the operating state . Preferably, the end elements comprise three longitudinal portions , wherein the first longitudinal portion is an insertion portion which is inserted in the tube element and the second longitudinal portion being arranged between first and third longitudinal portions is a flange portion abutting against a longitudinal end of the tube element and wherein a third longitudinal portion is a fastening portion which comprises said first fastening means arranged at a respective longitudinal end of the tubular housing provided by said end element . Preferably, the flange portion and the fastening portion together provide said contact surface , wherein in particular the flange portion comprises at least partially, in particular entirely, said second surface section of the contact surface , and the fastening portion comprises at least partially, in particular entirely, said first surface section of the contact surface . Preferably, the flange portion is welded or glued to the tube element thereby providing a seal surrounding the interior space in an uninterrupted manner . The insertion portion preferably has a geometric shape corresponding to the shape of the inner side of the tube element such that by only inserting the insertion portion inside the tube element the end element is rotationally fixed with regard to the tube element , i . e . the insertion portion alone being arranged inside the tube element avoids rotation in any direction of the end element relative to the tube element . This avoidance of rotation refers to a rotation around the tube axis , and this avoidance may be reali zed by abutting portions comprised by the insertion portion and abutting portions comprised by the tube element , wherein said abutting portions abut against each other when the insertion portion being inserted inside the tube element with an abutting direction which is perpendicular to the tube axis . Thus , the end element is fixed to the tube element making use of two di f ferent principals : the flange portion guarantees a reliable seal , whereas the insertion portion guarantees avoidance of rotation between tube element and end element such that the seal provided by the flange portion is not stressed due to a rotational force acting on the end element relative to the tube element . Preferably, the abutting portions of the tube element are provided by said proj ections of the tubular housing which form the fixing means of the tubular housing . The flange portion may at its first longitudinal side be sealingly connected to the tube element , and at its second longitudinal side in the operating state may be sealingly connected with the end cap, in particular via a gasket as disclosed with regard to embodiments in the present application . Preferably, in the operating state , each of the end caps is fixed to the tubular housing only via respectively one of the end elements to which it is associated . Accordingly, the end element alone , in this particular embodiment , provides a first fastening means to which the end cap is fixed with its second fastening means .

[0017] In one embodiment the gear tray is fixed to each of the end elements by a retaining means being arranged inside the interior space and being detachably fixed to the respective end element , wherein the end elements thereby define a longitudinal position of the gear tray relative to the tubular housing and / or define a vertical position of the longitudinal ends of the gear tray relative to the tubular housing . The retaining means may be detachably connected to the respective end elements , e . g . , by screwing or snap fitting . Preferably, the retaining means close only a portion of the free cross-section of the tubular housing, wherein by closing said portion of the free cross-section, the position of the gear tray within the tubular housing is defined, and by leaving open another portion of the free cross-section through wiring may be guided through this other portion .

[0018] According to another solution of the above-mentioned obj ective technical problem, the present invention proposes a modular set in which the end elements each comprises a welding line area surrounding continuously a tube axis , wherein the end elements each are attached to the respective longitudinal end of the tube element along the welding line area . The welding line area, accordingly, is a continuous line connecting the end element with the tube element continuously around the tube axis , thereby providing a sealed connection between the tube element and the end element . The welding line area is an area which serves for welding connection between a tube element and the end element . Welding can be done , preferably, by ultrasonic welding . In particular, the welding is done by mechanical movement of the tube element relative to the end element , in particular in combination with generation of heat . In particular, the welding between tube element and end element is reali zed without adding any additives , such that the tube element and the end element are connected throughout the welding line area by means of only the materials from which they are formed . In one embodiment , each end element and / or the respective longitudinal end of the tube element to which it is fixed, comprises a groove surrounding the tube axis and surrounding the welding line area . By providing such groove , accumulation of material during the welding process at the outside of the welding line area, in particular at the outside of the tubular housing, can be ef fectively avoided, since material accumulated during the welding process can be arranged within the groove , e . g . can move into the groove during welding, respectively during accumulation . Preferably, each end element comprises a connection line area surrounding continuously the tube access , the welding line area and the groove , wherein in the operating state the connection line area is in contact with the tube element . By providing such connection line area, which in particular surrounds continuously the tube axis , the welding line area and the groove , the end element can lie in direct connection at the tube element , which is advantageous not only with regard to the design of the tubular housing but also with regard to avoidance of accumulation of dirt at the connection area between end element and tube element as well as with regard to a durable sealing, respectively fixation, between the end element and the tube element . In one embodiment the welding line area is formed by a longitudinal proj ection of the respective end element . The proj ection proj ects along the longitudinal direction with regard to neighbored sections . By providing such welding line area in form of a longitudinal proj ection, the welding process can be reali zed easily . In one embodiment , said longitudinal proj ection is arranged next to or within said groove and longitudinally proj ects both with regard to the groove and with regard to a surface area being arranged at a side of the groove which is opposite to the side of the groove at which the proj ection is arranged . Accordingly, the longitudinal proj ection proj ects with regard to both areas between which it is situated, wherein, of course , this refers to a radial direction, i . e . the longitudinal proj ection is in a preferable embodiment situated with regard to the radial direction between two radially adj acent areas and proj ects with regard to these areas . The radial direction refers to the radial direction with regard to the tube axis . In case a groove is arranged at both sides of the longitudinal proj ection, material which accumulates during welding process can be particularly advantageously trapped in these groups .

[0019] As a further solution of the obj ective technical problem, the present invention proposes a modular set , wherein the tubular housing comprises a pair of installation channels at its outer top side being spaced apart from each other in a transverse direction . Each of the installation channels provides a transverse proj ection . The set comprises an installation element corresponding to at least one of the installation channels which has a hook which, in the operating state , is inserted in the respective installation channel and abuts against a lower side of the transverse proj ection to allow installation of the tubular housing at a ceiling with its outer top side facing the ceiling by fastening the installation elements to the ceiling . Accordingly, for installation the tubular housing at a ceiling, the hook engages with the transverse proj ection provided by the installation channel . In one embodiment , the installation element corresponds to both installation channels and has a first and a second hook, wherein the installation element is an elastic clamp having two clamp arms each of it forming one of the hooks . In the operating state , the installation element is snap- fitted with each of the hooks in respectively one of the installation channels . In an alternative embodiment , the modular set comprises at least a first and a second installation element , each comprising only one hook being arranged in only one of the installation channels in the operating state . Of course , said two alternative embodiments can be combined in a way that the set comprises both first and second installation elements as described and the one installation element having first and second hooks , wherein either the installation element with a first and second hooks or first and second installation elements can be alternatively inserted inside the installation channels for installing the tubular housing at the ceiling . In one embodiment , each of first and second installation element has a shape of an angle bracket and is designed to be inserted from the outer top side of the tubular housing inside each one of the installation channels , wherein in the operating state a first arm of the angle bracket is abutting against a lateral side of the installation channel and a second arm of the installation element is abutting against the transverse proj ection of the installation channel . By being designed in the shape of an angle bracket , the installation element itsel f can provide the form of a hook . Being formed in the shape of an angle bracket , this installation element can quite easily be inserted inside the installation channel although this installation channel provides the lateral proj ection . In one embodiment , the installation element , respectively each of first and second installation elements , is formed as an angle bracket as described above , wherein it comprises a slot in at least one of its arms . This slot can be advantageous for fixing an installation cable to the installation element . In one embodiment , the modular set comprises an installation cable having a fixation end, wherein the installation cable is designed to be inserted into the slot of the installation element , wherein in the operating state the fixation end is abutting against the lower side of one of the arms of the angle bracket which at least partially forms the slot . Preferably, the installation cable is fixed, in particular with its other end, to a ceiling thereby fixing the tubular housing to the ceiling . Preferably, in the operation state , the slot is situated within the installation channel prohibiting the installation cable to be moved out of the slot . In one embodiment , the installation element has a conical groove at the end of the slot having a groove diameter decreasing along its upwards extension . The conical groove is particularly advantageous for keeping a fixation end of an installation cable at its desired place in the operating state .

[0020] In one embodiment , each installation channel is connected to a transverse or lower outer side of the tubular housing by means of a tubular connection line having an opening at the longitudinal end of the housing allowing water being arranged inside the installation channel to flow out of the installation channel . By providing such tubular connection line , it is avoided that water remains inside the installation channel . By providing the opening at the longitudinal end of the tubular housing, the design properties of the tubular housing can be improved . In one embodiment , the tubular connection line comprises a passage being provided in one of the end elements . In one embodiment , a tubular connection line is formed by said passage being provided in one of the end elements . Since an end cap is fixed in the operating state to the end element , by providing this passage , this passage can be hidden by the end cap, wherein in particular this passage as an open end which is the open end of the tubular connection line which ends into an open space which is provided between the end cap the end element in the operating state so that water easily can flow out of the installation channel through this passage . According to another solution proposed by the present invention for solving the above-mentioned obj ective technical problem, the modular set comprises an installation element which is formed as an elastic clamp having to clamp arms , wherein the modular set comprises an anti-theft device , wherein in the operating state the elastic clamp embraces the anti-theft device with regard to the transverse direction such that in the operating state the anti-theft device prohibits deflection of the arms vs . each other . Since the elastic clamp, in the operating state , embraces the anti-theft device , the anti-theft device is situated, in the transverse direction, between the arms of the elastic clamp . The elastic clamp is designed to engage the installation channels described above . The clamp arms each provide a hook at their respective transverse ends facing away from each other with regard to the transverse direction, such that the elastic clamp can only be removed from the top side of the tubular housing by deflecting the elastic clamp in a way that the clamp arms are approached to each other with regard to the transverse direction . By arranging the anti-theft device in the transverse direction between the clamp arms , wherein the anti-theft device in particular abuts with regard to the transverse direction against each of the clamp arms , the anti-theft device can avoid removing of the installation element , respectively elastic clamp, from the tubular housing starting from the operating state . Accordingly, the anti-theft device has to be removed first , before the installation element can be removed from the housing . In one embodiment , the anti-theft device comprises at least two separate parts which, in the operating state , are fixed by a longitudinal snap- fit to each other . Accordingly, in order to uninstall the antitheft device in order to allow removing of the installation element from the tubular housing, first said two parts have to be loosened from each other and then these two parts can be moved away from each other along the longitudinal direction . In one embodiment , a first one of these parts comprises a hook being engaged with a proj ection of a second one of these parts , wherein one of these parts comprises a detachment channel having an opening at one longitudinal end of this part facing away from the other part , wherein the hook is accessible through this detachment channel in the operating state in order to allow deflection of the hook for loosening these two parts . Accordingly, the hook is accessible through said detachment channel , wherein in particular said two parts can only be removed from each other along the longitudinal direction, and wherein they can only be removed from each other after the hook has been deflected before , while this deflection can be done through said detachment channel , for example by making use of a screwdriver .

[0021] According to another solution proposed by the present invention for solving the above-mentioned obj ective technical problem, the modular set comprises a stabili zation profile which is adapted to the outer top side of the tubular housing and which has at least the same length as the tubular housing . In one embodiment , the stabili zation profile has a U-shaped cross-section with a vertical open end, wherein this vertical open end is directed downwards and faces the outer top side of the tubular housing in the operating states . The stabili zation profile has a higher sti f fness than the tubular housing . In the operating state , the stabili zation profile is fixed to the housing and covers the outer top side of the tubular housing . In one embodiment , the stabili zation profile is made of metal , whereas the tubular housing is made of plastics . The stabili zation profile allows easy stabili zation of the tubular housing which has a very large length and further can allow simple installation of such a long tubular housing . Preferably, the stabili zation element has with, i . e . extension along the transverse direction, which is at least as large as the width of the tubular housing . Preferably, the stabili zation profile embraces an upper section of the tubular housing . In one embodiment , the stabili zation profile is fixed, in the operating state , by a first number of fixation elements to the outer top side of the housing, in particular of the outer top side of a plurality of tubular housings which are arranged behind each other along the longitudinal direction . Further, the stabili zation profile is fixed by a second number of fixation elements to a ceiling, wherein the second number amounts to less than 50% , in particular less than 30% of the first number . Said fixation elements can for example be reali zed by the illustrated installation element being formed as an elastic clamp . Since the stabili zation profile has a higher sti f fness than the tubular housing, the stabili zation profile can be fixed by a lower number of fixation elements to the ceiling, whereas the tubular housing can be fixed by a higher number of fixation elements to the stabili zation profile , wherein in particular the stabili zation profile covers at least partially, in particular predominantly, in particular completely said fixation elements by which the tubular housing is fixed to the stabili zation profile , along the vertical extension of said fixation elements . In one embodiment , the stabili zation profile has an opening allowing access to a space between the outer top side of the tubular housing and the bottom side of the stabili zation element . Preferably, this opening is an opening at a transverse side of the stabili zation profile . In one embodiment , said opening, in the operating state , is arranged along a same longitudinal section as one of the fixation elements for allowing access to this fixation element . Preferably, said fixation element can be loosened from the stabili zation profile and / or the tubular housing by accessing said fixation element from a transverse outer side of the stabili zation profile through said opening . Accordingly, said stabili zation profile , said tubular housing, said fixation element and said opening are configured to interact in a way that the respective loosening of said fixation element is possible through said opening .

[0022] In one embodiment , the end cap and the tubular housing both have a rectangular cross-section . Preferably, the end cap be removed from the tubular housing by turning around the tube axis while the stabili zation profile remains fixed to the housing . Preferably, in the operating state , the stabili zation profile extends along the longitudinal direction over the end cap in order to cover the end cap which is advantageous not only with regard to the design of a luminaire but also with regard to stability of the luminaire reali zed by said set . The stabili zation profile , however, can be configured with regard to the end cap for allowing turning the end cap around the tube axis , for example by reali zing the stabili zation profile with the U- shaped cross-section or by providing an opening at the lower side of the stabili zation profile which is adapted to the shape of the end cap .

[0023] In one embodiment , the modular set comprises at least two tubular housings which are arranged behind each other along the longitudinal direction . In one embodiment , the stabili zation profile longitudinally extends continuously along both tubular housings .

[0024] According to a further solution of the above-mentioned obj ective technical problem proposed by the present invention, the modular set comprises a cover element for connecting two tubular housings as well as two connection end caps . In an advanced operating state , the two tubular housings each have one longitudinal end which faces the other tubular housing along the longitudinal direction . Accordingly, the respective two ends of said two tubular housings are facing each other along the longitudinal direction . Respectively one of the connection end caps is detachable and sealingly fixed to each of said longitudinal ends of the two tubular housings facing each other, wherein the cover element is non-sealingly fixed to each of the connection end caps surrounding a non-sealed interior space between said two tubular housings . Accordingly, the interior space of each of said two tubular housings is closed by the respective connection end cap, wherein the space between said two tubular housings being arranged behind each other is covered in a non-sealing manner by said cover element . This provides on the one hand easy sealing of the interior space of each of said two tubular housings and at the same time provides a continuous shape of a luminaire being reali zed in the advanced operating state . Preferably, the cover element has the same shape as said two tubular housings . Accordingly, the outer side of said cover element , in the advanced operating state , is flushed with regard to the outer side of said two tubular housings between which it is arranged .

[0025] In one embodiment , the set comprises a tubular connection element as well as a plurality of the tubular housings . Each of the tubular housings has features as described in the present application with regard to one of the embodiments of the set , wherein in particular each of the tubular housings is identically, such that it has identically shape . The tubular connection element is configured to be mounted between two of these tubular housings in an elongated operating state of the set in which an elongated luminaire is reali zed . The elongated operating state is a further arrangement of the components of the set . The components of the set which are connected to each other in the elongated operating state which are also connected to each other in the operating state may be connected in identical manner as described with regard to the operating state , and the further properties of the luminaire described in the operating state may be present in the elongated operating state . In the elongated operating state , the tubular connection element is detachably fixed to both tubular housings at their ends facing each other, wherein the tubular connection element and the tubular housings with their inner sides together confine an interior space of the elongated luminaire . Preferably, in the elongated operating state of the set , respectively one of the end caps is attached to that longitudinal end of respectively one of the tubular housings which faces away from the longitudinal end to which the tubular connection element is fixed, such that the interior space of the elongated luminaire is defined together by the end caps , the tubular housings and the tubular connection element . The tubular connection element , in particular, has a length along the longitudinal direction which amounts to less than 50 % , in particular less than 30 % of the length of each of the tubular housings . Since the tubular connection element is configured to be mounted between two of the tubular housings , an elongated luminaire can be reali zed with an uninterrupted interior space which extends throughout both tubular housings and the tubular connection element connecting said tubular housings . Each of the tubular housings , of course , has two longitudinal ends facing away from each other . These longitudinal ends define the length of the tubular housing . In one embodiment , in which each of the tubular housings with one of its longitudinal ends is connected to the tubular connection element and with the other one of its longitudinal ends is connected to an end cap, a sealed interior space is provided which is described in the present application with regard to various embodiments concerning the operating state . In one embodiment , the tubular connection element has a third fastening means at each of its longitudinal ends , the first fastening means and the third fastening means corresponding to each other to allow fastening of the tubular connection elements to each end of each of the tubular housings providing a press- fit between the tubular connection element and the longitudinal end to which it is fixed such that the tubular connection element is pressed along a contact surface of the tubular housing which surrounds the interior space at the longitudinal end against the tubular housing . The contact surface of the tubular housing is associated to one particular longitudinal end of the tubular housing . Accordingly, in the operating state in which a particular tubular housing is used which is also used in the elongated operating state , each of the end caps is pressed against the contact surface of the longitudinal end of the tubular housing to which it is associated, wherein in the elongated state the tubular connection element is pressed against the contact surface of one of the longitudinal ends and one of the end caps is pressed to the contact surface of the other longitudinal end . The properties of said fastening between third and first fastening means as well as the design of first and third fastening means can be reali zed as described in various embodiments with regard to first and second fastening means , wherein the respective longitudinal end of the tubular connection element which comprises the third fastening means may be fixed to the first fastening means of the respective longitudinal end of the tubular housing in a manner as described for the second fastening means of the end caps by which the end cap is fixed to the respective longitudinal end of the tubular housing . Particularly, the third fastening means may be arranged at an inner side of the tubular connection element . Preferably, the third fastening means are designed in the same manner as the second fastening means . Preferably, the third fastening means are provided at an inner side of an end portion of the tubular connection element , whereas the first fastening means are provided at an outer side of an end portion of the tubular housing . By designing the tubular connection element in such a way that it can be connected to the tubular housing at each of its longitudinal ends , and by providing end caps which can be fixed to each longitudinal ends of the tubular housing, assembly of the modular set for reali zing an elongated luminaire is remarkably simpli fied, and manufacturing costs are lowered due to making use of identical components , respectively identically designed components . In one embodiment , the tubular connection element , at its inner side , comprises a fixation means .

[0026] According to a further solution of the above-mentioned obj ective technical problem proposed by the present invention, the tubular connection element is flexible in length, while the tubular housings are inflexibly length . This allows easy and durable installation of said tubular housings for reali zing the elongated operating state , since relative movement of said two tubular housings relative to each other can be compensated by said flexible connection element . Preferably, said connection element has a lower sti f fness than said two tubular housings . Preferably, said connection element can be elastically deformed by changing its length and / or its outer shape . Preferably, the set further comprises the surrounding element which, in the elongated operating state of the set , is mounted around the tubular connection element and covers the tubular connection element . In one embodiment , said surrounding element can be reali zed by the above illustrated cover element . Preferably, the set comprises a stabili zation profile , wherein said surrounding element is fixed to the stabili zation profile and by this stabili zation profile is fixed to said two tubular housings .

[0027] As a further solution of the above-mentioned obj ective technical problem, the invention proposes an optical element which has a plate-like shape with two plate surfaces facing away from each other, wherein the optical element extends with a thickness between said plate surfaces and is adapted to be used as the optical element of a system designed according to the invention . The optical element can have features which have been described with regard to various embodiments of the modular set .

[0028] As a further solution of the above-mentioned obj ective technical problem, the invention proposes a luminaire which is reali zed by an embodiment of the modular set , wherein the modular set is in one of its operating states , in particular in the operating state , the elongated operating state or in the advanced operating state .

[0029] As a further solution of the above-mentioned obj ective technical problem, the invention proposes a method for fabricating a luminaire by making use of an embodiment of the inventive modular set . In a first step, the gear tray to which a light module has been fixed before is inserted into the tubular housing and is fixed to the inner side of the tubular housing, in particular by means of said mounting element . In a second step one of the end caps is af fixed to each one of the longitudinal ends of the tubular housing thereby defining and sealing the interior space of the luminaire .

[0030] In one embodiment of the inventive modular set , the set comprises an additional gear tray being detachably fixed, in particular snap fitted, to the mounting element in the operating state at a vertical distance from the gear tray, in particular above the gear tray, in particular closer to the first mounting section than to the second mounting section of the mounting element . Preferably, the additional gear tray, in the operating state , is arranged closer to the upper end of the inner side of the tubular housing than to the bottom end of the inner side of the tubular housing . Preferably, the additional gear tray is spaced apart from the upper end of the inner side of the tubular housing by a vertical distance which is less than its vertical distance from the mounting panel of the gear tray and / or which is less than 1 / 4 , in particular 1 / 5 , in particular 1 / 6 of the maximum vertical extension of the interior space in the operating state . The mounting element , accordingly, preferably comprises a third mounting section corresponding to the additional gear tray for allowing detachable fixing of the additional gear tray to the mounting element and therethrough to the tubular housing . According to the preferable embodiment , the set comprises an additional light module , wherein, in the operating state , the additional light module is arranged on a top side of the additional gear tray facing away from the mounting panel of the gear tray, wherein light emanating from the additional light module in the operating state is emitted to the surroundings of the housing . The tubular housing comprises a top optical section being arranged above the bottom optical section and above the additional gear tray surrounding at least partially the top side of the additional gear tray, wherein in the operating state at least 90 % of the light emanating from the additional light module is emitted by the top optical section, in particular upwards . The manner of partially surrounding may be reali zed analogously as described above with regard to the surrounding of the bottom side of the mounting panel by the bottom optical section . Preferably, all of the light emitted by the additional light module in the operating state is emitted upwards by the top optical section . The top optical section is comprised by the mentioned top section . In one embodiment , the top section is reali zed as top optical section in its entirety . Provision of top and bottom optical section with the top optical section being arranged above the bottom optical section, while in particular said optical sections are nonoverlapping, allows to reali ze particularly high intensity of light emitted upwards by making use of the additional gear tray as well as the additional light module . Accordingly, the set according to the advantageous embodiment of the invention allows adaptation of the luminaire to be reali zed in the operating state to environments , where a high indirect illumination is desired . The top optical section may be comprised by the above- mentioned top section, in particular the top section is formed by the top optical section . Preferably, the top optical section is configured to emit , in the operating state , some of the light emanating from the additional light module into a same area of the surroundings of the luminaire into which the bottom optical section emits some of the light emanating from the light module . Accordingly, the light distribution angles of bottom and top optical sections in the operating state are overlapping . Preferably, the luminaire being reali zed by the set in its operating state is configured to emit an entire light intensity by the tubular housing, wherein at least 40 % of the entire light intensity is emitted downwards and at least 40 % of the entire light intensity is emitted upwards and wherein at least 5 % , in particular at least 10 % of the light emitted upwards is emanating from the light module . Accordingly, this embodiment of the inventive modular set on the one hand provides a remarkable amount of light emitted upwards by the light module which is arranged at the bottom side of the gear tray, whereas through the provision of the additional light module at the top side of the additional gear tray a luminaire can be reali zed in the operating state of the set which emits a remarkable amount of light both upwards and downwards . Therefore , the modular set allows easy reali zation of a luminaire which has an unobtrusive appearance and provides quite sophisticated lamination of surroundings . In one embodiment , the top optical section comprises a prismatic structure at its inner side .

[0031] The di f ferent solutions provided by the invention as well as their embodiments can particularly advantageously be combined . Accordingly, embodiments of each of the solutions described may have features which have been described with regard to embodiments of other solutions . Each solution as such is an own solution of the obj ective technical problem and therefore , in some embodiments disclosed with regard to the respective solution, does not necessarily have to comprise features described in the context of embodiments of other solutions , although such solutions may be combined advantageously . Further, inventive embodiments may have features which have been described with regard to modular sets , respectively luminaires , respectively methods as known in the prior art .

[0032] The invention is described in further details by describing illustrative embodiments of the inventive modular set making reference to nine figures which illustrate :

[0033] Figure 1 : in a schematic drawing a view of a luminaire reali zed by an embodiment of the inventive modular set ;

[0034] Figure 2 : in several schematic drawings various views of several components of an embodiment of the inventive set ;

[0035] Figure 3 : in a schematic drawing a partial view of some components of one embodiment of the inventive modular set ;

[0036] Figure 4 : in a schematic drawing a view of the tube element of one embodiment of the inventive modular set ;

[0037] Figure 5 : in several schematic drawings various views of several components of one embodiment of inventive modular set ;

[0038] Figure 6 : in several schematic drawings various views of several components of one embodiment of inventive modular set ;

[0039] Figure 7 : in several schematic drawings various views of several components of one embodiment of inventive modular set ;

[0040] Figure 8 : in several schematic drawings various views of several components of one embodiment of inventive modular set ;

[0041] Figure 9 : in several schematic drawings various views of several components of one embodiment of inventive modular set . In Figure 1 a luminaire reali zed by one embodiment of the modular set is shown quite schematically . The luminaire comprises a tubular housing as well as two end caps 2 , wherein each of said end caps 2 is fixed to respectively one longitudinal and of the tubular housing . At the outer top side of the tubular housing, the tubular housing comprises two installation channels being spaced apart from each other in a transverse direction, wherein at the outer top side there is arranged two clamp-like installation elements 3 as well as to anti-theft devices 4 , each anti-theft device 4 prohibiting a loosening of respectively one of said installation elements 3 .

[0042] Figure 2 comprising figures 2a, 2b, 2c and 2d shows various views of several components of one embodiment of the modular set . Figure 2a shows a cross-section perpendicular to the longitudinal direction . As can be seen from figure 2a, the tubular housing has a rectangular shape , in the present embodiment a square shape , with two sidewalls , wherein a first optical element 5 is attached to the inner side of a first sidewall and a second optical element 501 is attached to the inner side of a second sidewall . A third optical element 502 is attached to the inner side of the bottom wall of the tubular housing . At its top side , the tubular housing comprises two installation channels 11 being spaced apart from each other along a transverse direction . The installation channels 11 are parallel to each other . Both installation channels 11 provide a transverse proj ection which can be engaged by an installation element 3 , as seen, for example , in figure 1 , figure 6 and figure 7 . A mounting element 6 is fixed by a first mounting section to fixing means provided by the tubular housing . The mounting element 6 is shown alone in figure 2b . The gear tray 600 is fixed to the tubular housing, as shown in figure 2d, wherein a light module is fixed to a bottom side of the mounting panel of the gear tray 600 . The tubular housing provides two slots 151 , 152 into which the optical element 5 is snap- fitted . The optical element 5 has a plate-like shape with two plate surfaces facing away from each other . The optical element extends with a thickness between said plate surfaces . The optical element 5 comprises a first plate section 51 consisting of a first material as well as a second plate section 52 consisting of a second material . The first material is less light transmissive than the second material . Accordingly, the optical element 5 is more light transmissive in an upper section than in a lower section . The optical element 5 is pressed, through said snap- fit , against the inner side of one of said sidewalls . At the other sidewall , another optical element 501 is attached, whereas , in other embodiments not shown, an identical optical element 5 could also be respectively attached to the other sidewall , and in further embodiments , not shown, an identical optical element could also be used instead of the other optical element 502 and could be attached to the inner side of the bottom wall of the tubular housing .

[0043] From figures 2a, 2b, 2c and 2d, it can be obtained that the fixing means of the tubular housing comprises two racks 12 , each of which comprises a first vertical proj ection 121 proj ecting upwards as well as a second vertical proj ection 121 proj ecting downwards . The mounting element 6 comprises two clamp-like sidearms 61 , each of which has two vertical proj ections 610 . The vertical proj ections 121 of the racks 12 and the vertical proj ections 610 of the sidearms 61 of the mounting element 6 engage behind each other, thereby providing a durable fixation of the mounting element 6 with regard to the tubular housing . As can be seen from figure 3 , the tubular housing comprises a tube element 1 as well as two end elements 7 , each end element 7 being connected to one longitudinal end of the tube element 1 . The tube element 1 has an opening 13 for allowing insertion of a powerline . Each end element 7 has an opening 77 as well as a first fasting means 71 forming the first fastening means 71 of the tubular housing . The design of the tube element 1 is further shown in figure 4 . From figure 5 comprising figure 5a and 5b combination with figure 4 the design of the end element 7 as well as the fixation of the end element 7 with regard to the tube element 1 can be obtained . The end element 7 comprises said first fastening means 71 as well as a flange portion extending around the opening 77 as well as extending beyond the first fastening means 71 . In this flange portion, passages 72 of the end elements 7 are provided . Further, the end element 7 comprises fixation holes 73 which can be used for fixing a gear tray 600 . As can be seen from figure 5b, at its side facing the tube element 1 , the end element 7 has a welding line area 75 as well as a connection line area 76 . The welding line area 75 proj ects with regard to adj acent sections 751 , 752 , wherein said adj acent sections 751 , 752 form a groove in which the welding line area 75 is arranged . The welding line area 75 surrounds continuously the opening 77 and of course the tube axis . By welding this welding line area 75 to the longitudinal end of the tube element 1 shown in figure 4 , the tube element 1 and the end element 7 can be sealingly fixed to each other, wherein the material of the welding line area 75 during welding can be trapped inside said groove . After having reali zed the fixation of the end element 7 at the tube element 1 , the connection line area 76 abuts against the tube element 1 . The end element 7 further comprises and insertion portion 74 which is inserted into the tube element 1 before fixation and which remains inserted after fixation . This insertion portion 74 provides a strong fixation of the end element 7 which prohibits a rotation of the end element 7 with regard to the tube element 1 .

[0044] In figure 6 comprising the figures 6a and 6b an installation element 3 as well as an anti-theft device 4 is shown . The installation element 3 is designed like a clamp having two clamp arms each providing a hook 31 , 32 . Said two clamp arms are connected by a connection section 33 of the clamp-like installation element 3 . In the operating state , the hooks 31 , 32 are inserted in the respectively one of the installation channels 11 of the tube element 1 and abut against the lower side of the transverse proj ection of the respective installation channel 11 . The installation element 3 , in the operating state , embraces the anti-theft device 4 . Accordingly, the anti-theft device 4 , in the operating state , prohibits deflection of the side arms , respectively of the installation element 3 . The anti-theft device 4 comprises a first part 41 and a second part 42 . The first part 41 comprises a hook 411 as well as a guide 412 . For reali zing the operating state , first and second part 41 , 42 are moved to each other along the longitudinal direction being guided by the guide 412 , wherein the hook 411 , in the operating state , is engaged with the proj ection of the second part 42 . The second part 42 comprises a detachment channel through which the hook 411 is accessible in order to allow deflection of the hook 411 for loosening these two parts 41 , 42 starting from the operating state .

[0045] In figure 7 comprising figure 7a and 7b an installation element 8 being formed like an angle bracket having a first arm 82 and a second arm 83 is shown . The installation element 8 has a slot 84 which extends in each of its arms 82 , 83 . At the end of the slot 84 , there is a conical groove 81 having a groove diameter decreasing along its upwards extension in the operating state . In this groove 81 , there can be maintained a fixation end 801 of an installation cable 800 . As can be seen from figure 7b, in the operating state the installation element 8 is inserted in an installation channel 11 , wherein one of its arms abuts against the lower side of the transverse proj ection, and the other one of its arms abuts against a lateral side of the installation channel 11 .

[0046] In figure 8 comprising figures 8a, 8b and 8c, an embodiment comprising a stabili zation profile 9 is shown . The stabili zation profile 9 has a U-shaped cross-section with a vertical open end facing the outer top side of the tubular housing . The stabili zation profile 9 extends over both the tubular housing, of which the tube element 1 is shown, as well as over both end caps 2 in the operating state . The stabili zation profile 9 is fixed by installation elements 300 relative to the tube element 1 . Generally, such installation element 300 can be the fixation elements described in various embodiments . The stabili zation profile 9 has an opening 90 through which the installation element 300 is accessible . The stabili zation profile 9 further has a proj ection 91 at each of its sidewalls which, e . g . , allow fixation of a cover element , respectively a surrounding element . As can be seen from figure 8c, the end cap 2 can be removed from the tubular housing by turning the end cap 2 with regard to the tubular housing while the stabili zation profile 9 remains in place .

[0047] In figure 9 comprising figures 9a, 9b, 9c and 9d a modular set is shown which comprises a tubular connection element 100 which is flexible . Said connection element 100 has fastening means 102 by which it can be connected to the end elements 700 of two neighbored housings , as shown in figure 9b . The tubular connection element 100 has a convoluted section 101 providing the flexibility of the tubular connection element 100 , which is in general advantageous . The modular set according to figure 9 further comprises a surrounding element 10 which has proj ections 11 which are designed corresponding to the proj ections 91 of the stabili zation profile 9 , as shown in the embodiments illustrated in figure 8 . Through these proj ections 11 , the surrounding element 10 can be mounted to the stabili zation profile 9 , thereby surrounding the tubular connection element 100 .

[0048] Reference signs list tube element end cap installation element anti-theft device optical element mounting element end element installation element stabili zation profile surrounding element installation channel rack opening hook hook connection section first part second part first plate section second plate section clamp-like sidearm first fastening means passage fixation hole insertion portion welding line area connection line area opening conical groove first arm second arm slot opening proj ection tubular connection element convoluted section fastening means vertical proj ection slot slot installation element hook guide second optical element third optical element gear tray vertical proj ection end element adj acent section adj acent section installation cable fixation end

Claims

Claims1 . Modular set for realising a luminaire , the set comprising a tubular housing extending along its tube axis over a length in a longitudinal direction as well as over a height along a vertical direction being perpendicular to the longitudinal direction, a gear tray ( 600 ) having a mounting panel with a top side and a bottom side , a light module and at least two end caps ( 2 ) , wherein in an operating state of the set , in which the luminaire is reali zed, each of the end caps ( 2 ) being detachably and sealingly fixed to the tubular housing closing a longitudinal end of the tubular housing associated to the respective end cap ( 2 ) , the gear tray ( 600 ) being arranged within an interior space defined by an inner side of the tubular housing and the end caps ( 2 ) , and the light module being attached to the bottom side of the mounting panel of the gear tray ( 600 ) , wherein in the operating state light emanating from the light module is emitted to surroundings of the luminaire from the tubular housing with a luminous flux, wherein the tubular housing comprises a fixing means at its inner side , wherein in the operating state the gear tray ( 600 ) is fixed to the fixing means of the tubular housing the bottom side of its mounting panel being arranged at a vertical distance from a bottom end of the inner side of the tubular housing, wherein themodular set comprises an optical element (5) having a platelike shape with two plate surfaces facing away from each other, the optical element (5) extending with a thickness between said plate surfaces and, in the operating state, being attached to the inner side of the tubular housing extending in a particular direction being perpendicular to the longitudinal direction over at least 50 %, in particular at least 70 %, of the extension of the tubular housing in said particular direction and one of its plate surfaces facing the inner side of the tubular housing, characterized in that the optical element (5) comprises a first plate section (51) consisting of a first material and a second plate section (52) consisting of a second material, wherein the first material is less light transmissive than the second material, wherein the first and second plate sections (51, 52) each have a thickness forming at least partially the thickness of the optical element (5) and both extend along a same overlapping section along the plate surfaces of the optical element (5, 501, 502 in which overlapping section each of them forms a portion of the thickness of the optical element (5) , wherein a ratio between the portion of the thickness of the optical element (5) being formed by the first plate section (51) and the portion of the thickness of the optical element (5) being formed by the second plate section (52) decreases along the upwards vertical direction, wherein in particular each of the plate sections (51, 52) have a maximum thickness of at least 0,5 mm, in particular at least 1 mm, in particular at least 1,5 mm within the overlapping section, wherein in particular the optical element (5) has a maximum thickness of at least 2 mm, in particular at least 3 mm, and in particular of less than 7mm, in particular less than 5 mm within the overlapping section .

2. Modular set according to claim 1, characterized in that the first and second plate section (51, 52) each extend along at least 30 % of the plate surfaces of the optical element (5, 501, 502) , wherein in particular in an upper section of the optical element (5) the second plate section forms at least 80 % of the thickness of the optical element (5) and in a lower section of the optical element (5) the first plate section forms at least 80 % of the thickness of the optical element (5) , wherein in particular the overlapping section extends at least over 50 %, in particular at least 70 % of the optical element () in said particular direction.

3. Modular set according to any one of claims 1 or 2, characterized in that each one of first and second plate sections (51, 52) forms a portion of at least one of the plate surfaces of the optical element (5, 501, 502) , in particular of both plate surfaces, wherein in particular the first plate section (51) forms a portion of both plate surfaces in a lower section of the optical element (5) and the second plate section (52) forms a portion of both plate surfaces in an upper section of the optical element (5) .

4. Modular set according to any one of claims 1 to 3, characterized in that the optical element (5) and each of first and second platesections have a same cross-section along at least 70 % of their length, wherein in particular the optical element (5is produced by coextrusion using the first and second material.

5. Modular set according to any one of claims 1 to 4, characterized in that the optical element (5) is fixed to the tubular housing by a snap-fit being arranged in an upper and a lower slot (151, 152) of the tubular housing.

6. Modular set according to any one of claims 1 to 5, characterized in that the set comprises a mounting element (6) having a first mounting section corresponding with the fixing means of the tubular housing as well as a second mounting section corresponding with the gear tray (600) , wherein in the operating state the mounting element (6) is fixed, in particular releasably fixed, with its first mounting section to the tubular housing and is fixed, in particular releasably fixed, with its second mounting section to the gear tray (600) thereby fixing the gear tray (600) to the tubular housing, wherein the fixing means of the tubular housing is designed in the form of two racks (12) each being arranged at an inner side of a sidewall of the tubular housing, wherein each rack (12) comprises a vertical projection (121) , wherein the first fixing means of the mounting element (6) comprises two clamp-like sidearms (61) which each engage behind the vertical projection (121) of one of the racks (12) .

7. Modular set according to claim 6, wherein each rack (12) comprises a first vertical projection(121) projecting upwards as well as a second vertical projection projecting downwards, wherein each sidearm (61) of the mounting element (6) engages behind each of the vertical projections (121) of the respective rack.

8. Modular set according to any one of claims 6 or 7, characterized in that the rack (12) extends along a transverse direction, which is perpendicular to the vertical and longitudinal direction, over a transverse length being in particular less that 10 mm, wherein the vertical projection (121) extends over a height which amounts to at least 25 % of the transverse length of the rack (12) .

9. Modular set according to any one of claims 6 to 8, characterized in that the first mounting section in the operating state is spaced apart vertically from the bottom side of the mounting panel of the gear tray (600) which is fixed to the second mounting section by at least 1 / 7 of a maximum vertical extension of the interior space, in particular by 1 / 6 to 1 / 4 of the maximum vertical extension of the interior space, and / or in that in the operating state the bottom side of the mounting panel to which the light module is attached is spaced apart vertically from the bottom end of the inner side of the tubular housing by at least 50 %, in particular at least 70 % of a maximum vertical extension of the interior space, wherein in particular the mounting element (6) extends along a bottom optical section of the tubular housing,wherein in particular the mounting element (6) has a U- shaped or H-shaped form having two flanks connected by a transverse connection rod, wherein the flanks at their upper ends together form the first mounting section and at their lower ends together form at least a part of the second mounting section.

10. Modular set according to any one of the preceding claims , characterized in that the tubular housing comprises a tube element (1) as well as two end elements (7, 700) each being connected undetachably, in particular welded, to respectively one longitudinal end of the tube element (1) , wherein in the operating state each of the end caps (2) is sealingly and detachably fixed to respectively one of the end elements (7, 700) , wherein in particular in the operating state each of the end caps (2) is fixed to the tubular housing only via respectively one of the end elements (7, 700) to which it is associated.

11. Modular set according to claim 10, characterized in that the end elements (7, 700) each comprise a welding line area (75) surrounding continuously the tube axis, wherein the end elements (7, 700) each are attached to the respective longitudinal end of the tube element (1) along the welding line area (75) , wherein each end element (7, 700) and / or the respective longitudinal end of the tube element (1) comprises a groove (81) surrounding the tube axis and surrounding the welding line area (75) .

12. Modular set according to claim 11,characterized in that each end element (7, 700) comprises a connection line area(76) surrounding continuously the tube axis, the welding line area (75) and the groove (81) , wherein in the operating state the connection line area (76) is in contact with the tube element (1) .

13. Modular set according to any of the claims 11 to 12, characterized in that the welding line area (75) is formed by a longitudinal projection of the respective end element (7, 700) , wherein in particular said longitudinal projection is arranged next to or within the groove (81) and longitudinally projects both with regard to the groove (81) and with regard to a surface area being arranged at a side of the groove (81) which is opposite to the side of the groove (81) at which the projection is arranged.

14. Modular set according to any one of the preceding claims , characterized in that the tubular housing comprises a pair of installation channels (11) at its outer top side being spaced apart from each other in a transverse direction, each of the installation channels (11) providing a transverse projection, wherein the set comprises an installation element (3, 8, 300) corresponding to at least one of the installation channels (11) and having a hook (31, 32) which, in the operating state, is inserted in the respective installation channel (11) and abuts against a lower side of the transverse projection to allow installation of the tubular housing at a ceiling with its outer top side facingthe ceiling by fastening the installation element (3, 8, 300) to the ceiling.

15. Modular set according to claim 14, characterized in that the installation element (3, 300) corresponds to both installation channels (11) and has a first and a second hook (31, 32) , wherein the installation element (3, 300) is an elastic clamp having two clamp arms each of it forming one of the hooks (31, 32) , wherein in the operating state the installation element (3, 300) is snap-fitted with each of the hooks (31, 32) in respectively one of the installation channels (11) or in that the modular set comprises at least a first and a second installation element (8) each comprising only one hook being arranged in only one of the installation channels (11) in the operating state, wherein in the operating state the first installation element (8) is inserted in a first installation channel (11) and the second installation element (8) is inserted in a second installation channel (11) , wherein the installation element (8) has a shape of an angle bracket and is designed to be inserted from the outer top side of the tubular housing inside the installation channel (11) , wherein in the operating state a first arm (81, 82) of the angel bracket is abutting against a lateral side of the installation channel (11) and a second arm (81, 82) of the installation element (8) is abutting against the transverse projection of the installation channel (11) .

16. Modular set according to claim 15, characterized in thatthe installation element (8) is formed as an angle bracket having first and second arms and comprises a slot (84) in at least one of its arms (81, 82) , wherein in particular the modular set comprises an installation cable (800) having a fixation end, wherein the installation cable (800) is designed to be inserted into the slot (84) of the installation element (8) , wherein in the operating state the fixation end is abutting against a lower side of one of the arms of the angle bracket which at least partially forms the slot (84) and is fixed to a ceiling thereby fixing the tubular housing to the ceiling.

17. Modular set according to claim 16, characterized in that the installation element (8) has a conical groove (81) at the end of the slot (84) having a groove diameter decreasing along its upward extension.

18. Modular set according to any one of the claims 14 to 17, characterised in that each installation channel (11) is connected to a transverse or lower outer side of the tubular housing by means of a tubular connection line having an opening at a longitudinal end of the housing allowing water being arranged inside the installation channel (11) to flow out of the installation channel (11) , wherein the tubular connection line comprises a passage being provided in one of the end elements (7, 700) .

19. Modular set according to claim 15 or 18, characterized in thatthe installation element (3, 8, 300) is an elastic clamp having two clamp arms, wherein the modular set comprises an anti-theft device (4) , wherein in the operating state the elastic clamp embraces the anti-theft device (4) with regard to the transverse direction such that in the operating state the anti-theft device (4) prohibits deflection of the arms versus each other.

20. Modular set according to claim 19, characterized in that the anti-theft device (4) comprising at least two separate parts (41, 42) which, in the operating state, are fixed by a longitudinal snap-fit to each other, wherein in particular a first one of these parts (41) comprises a hook (31, 32) being engaged with a projection of a second one of these parts (41, 42) , wherein one of these parts (41, 42) comprises a detachment channel having an opening at one longitudinal end of this part (41, 42) facing away from the other part (41, 42) , wherein the hook (31, 32) is accessible through this detachment channel in the operating state in order to allow deflection of the hook (31, 32) for loosening these two parts (41, 42) .

21. Modular set according to any one of the preceding claims , characterized in that the modular set comprises a stabilization profile (9) , in particular having a U-shaped cross-section with a vertical open end, which is adapted to the outer top side of the tubular housing and which has at least the same length as the tubular housing, wherein the stabilization profile (9) has a higher stiffness than the tubular housing and wherein,in the operating state, the stabilization profile (9) is fixed to and covers the outer top side of the tubular housing .

22. Modular set according to claim 21, characterized in that the stabilization profile (9) is fixed, in the operating state, by a first number of fixation elements to the outer top side of at least one housing, in particular a plurality of tubular housings, as well as by a second number of fixation elements to a ceiling, wherein the second number amounts to less than 50 %, in particular less than 30 % of the first number.

23. Modular set according to any one of claims 21 or 22, characterized in that the stabilization profile (9) has an opening (90) allowing access to a space between the outer top side of the tubular housing and the bottom side of the stabilization profile (9) , wherein in particular said opening, in the operating state, is arranged along a same longitudinal section as one of the fixation elements for allowing access to this fixation element.

24. Modular set according to any one of the claims 21 to 23, characterized in that the end cap (2) and the tubular housing both have a rectangular cross-section, wherein the end cap 82) can be removed from the tubular housing by turning around the tube axis while the stabilization profile (9) remains fixed to the housing.25 . Modular set according to any one of claims 21 to 23 , characteri zed in that the modular set comprises at least two tubular housings being arranged behind each other along the longitudinal direction, wherein the stabili zation profile ( 9 ) longitudinally extends continuously along both tubular housings .26 . Modular set according to any one of the preceding claims , characteri zed in that the modular set comprises a cover element for connecting two tubular housings as well as two connection end caps , wherein, in an advanced operating state , the two tubular housings each have one longitudinal end which faces the other housing along the longitudinal direction, wherein respectively one of the connection end caps ( 2 ) is detachably and sealingly fixed to each of said longitudinal ends of the housings facing each other, wherein the cover element is non-sealingly fixed to each of the connection end caps ( 2 ) surrounding a non-sealed interior space between said two tubular housings .27 . Modular set according to claim 26 , characteri zed in that the cover element has the same outer shape as said two tubular housings .28 . Modular set according to any one of the preceding claims , characteri zed in thatthe set comprises a tubular connection element (100) as well as a plurality of the tubular housings, wherein the tubular connection element (100) is configured to be mounted between two of these tubular housings in an elongated operating state of the set in which an elongated luminaire is realized, wherein in the elongated operating state the tubular connection element (100) is detachably fixed to both tubular housings at their ends facing each other, the tubular connection element (100) and the tubular housings with their inner sides together confine an interior space of the elongated luminaire, wherein the tubular connection element (100) is flexible in length while the tubular housings are inflexible in length, wherein in particular the set further comprises a surrounding element (10) being, in the elongated operating state of the set, mounted around the tubular connection element (100) and covering the tubular connection element (100) .

29. Optical element (5, 501, 502) having a plate-like shape with two plate surfaces facing away from each other, the optical element (5, 501, 502) extending with a thickness between said plate surfaces and being adapted to be used as optical element (5, 501, 502) of the system according to any one of the preceding claims, characterized in that the optical element (5, 501, 502) comprises a first plate section (51) consisting of a first material and a second plate section (52) consisting of a second material, wherein the first material is less light transmissive than the second material, wherein the first and second plate sections each have a thickness forming at least partially the thickness of the optical element (5, 501, 502) and both extend along a same overlapping section along the platesurfaces of the optical element (5, 501, 502) in which overlapping section each of them forms a portion of the thickness of the optical element (5, 501, 502) , wherein a ratio between the portion of the thickness of the optical element being formed by the first plate section and the portion of the thickness of the optical element (5, 501, 502) being formed by the second plate section decreases along the upwards vertical direction, wherein in particular each of the plate sections have a maximum thickness of at least 1 mm, in particular at least 1,5 mm within the overlapping section, wherein in particular the optical element (5, 501, 502) has a maximum thickness of at least 2 mm, in particular at least 3 mm, and in particular of less than 7 mm, in particular less than 5 mm within the overlapping section.

30. Luminaire being realized by the modular set according to any of the preceding claims, the set being in one of its operating states.

31. Method for fabricating a luminaire making use of the set of any one of the claims 1 to 29, characterized in that in a first step, the gear tray (600) to which the light module is fixed is inserted into the tubular housing and fixed to the inner side of the tubular housing, wherein in a second step one of the end caps (2) is fixed to one of the longitudinal ends of the tubular housing thereby defining and sealing the interior space of the luminaire.

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