Patent Description:
Retractable lighting fixtures or poster like display boxes implement a flexible multilayer lighting sheet foil which can be rolled up on a roll or drum for transport or storage. Such poster like display boxes are used at events, such as conventions, or for promotions in retail environments, such as shops, galleries, showrooms, and the like. When unrolled, the flexible multilayer lighting sheet foil presents a display for illumination or advertisement/information purposes.

An example of such retractable lighting fixture or poster like display box is disclosed in <CIT>, in which the flexible multilayer lighting sheet foil is composed of a LED layer and an information containing optical layer. Both layers forming the flexible multilayer lighting sheet foil are rolled on a drum. When unrolled, a specific spacer mechanism connected with the layers, is activated, causing both layers to be spaced apart for a proper, effective illumination of the information containing optical layer using the LED layer.

This makes the construction of <CIT> unnecessarily complex and expensive. In addition, the retractable lighting fixture of <CIT> does not facilitate an (easy) exchange of the optical layer, which is essential for a poster backlighting solution. It is an object of the disclosure to provide a retractable lighting fixture having a simplified construction allowing a proper, effective illumination of the information containing optical layer using the LED layer as well as exchange of the optical layer.

According to a first aspect of the disclosure a retractable lighting fixture is proposed, comprising a rotatable drum; and a flexible multilayer lighting sheet movable between a retracted position and an extended position more than the retracted position, with the multilayer lighting sheet in the retracted position being at least partially retracted in one or more windings around the rotatable drum and with the multilayer lighting sheet in the protracted position being fully unwound from the rotatable drum; with the multilayer lighting sheet being composed of at least one LED layer and at least one diffusing optical layer, the at least one LED layer having a first LED layer edge mounted at a first mounting position at the outer circumference of the rotatable drum and the at least one diffusing optical layer having a first optical layer edge mounted at a second mounting position at the outer circumference of the rotatable drum, the first mounting position being located at an arc length along the circumference from the second mounting position.

With the at least one LED layer and the at least one diffusing optical layer being mounted at different mounting positions at the outer circumference of the drum, the layers will be automatically spaced apart from each other, when fully unwound and protracted from the drum. No additional spacer mechanism is required and due to the spacing thus created a correct and effective illumination of the information containing optical layer by means of the LED layer is achieved.

In an example the arc length between the first mounting position and the second mounting position may range between <NUM>°-<NUM>°, in particular between <NUM>°-<NUM>°. Herewith specific spacing distances, equal to the chord of the respective arc length, between the layers can be achieved in the fully unwound or unrolled, protracted orientation, thus achieving a desired illuminance of the optical layer and hence an optimal visualization and presentation of the information contained thereon.

In an advantageous example, the first mounting position and the second mounting position are located at opposite sides of the rotatable drum, thus achieving a spacing between the layers in the fully unwound or unrolled, protracted orientation equal to the diameter of the drum.

In a further example according to the disclosure the drum comprises at least one further mounting position different from the first mounting position and the second mounting position. Herewith the at least one LED layer and the at least one optical layer can be mounted to the drum at several different mounting positions, allowing an easy exchange of one of the layers, but also to select the correct spacing defined by the chord corresponding with the arc length between the mounting positions of the at least one LED layer and the at least one optical layer, respectively. The possibility to select the correct (chord) spacing between the layers allows for a simple adjustment or selection of the proper, desired illuminance of the at least one optical layer using the LED layer.

Preferably, the mounting positions are located at equidistant arc lengths from each other, for example at equidistant arc lengths of <NUM>°, <NUM>° or <NUM>°, thus effectively presenting a retractable lighting fixture with a rotatable multi-spacing drum, allowing the multilayer lighting sheet to be set up in the fully unwound or unrolled, protracted orientation with a spacing which can be selected in advance by mounting the at least one LED layer and the at least one optical layer in positions distanced by a pre-selected arc length.

In an improvement of the disclosure, each first, second and further mounting position are configured as a first, second and further groove respectively, each groove provided in the outer circumference of the drum and structured to accommodate one of the first LED layer edge and the first optical layer edge, respectively. This allows the LED and optical layers to be easily inserted and secured to the rotatable drum.

Preferably, the grooves extend in the longitudinal direction of the drum, thus allowing a proper accommodating of the free layer edge of each LED layer and optical layer in their respective groove. Also, with the grooves present in the outer circumference of the rotatable drum and the free edges of the layer mounted therein an improved rolling up and down of multilayer lighting sheet is achieved without the risk of folds, greases, wrinkles or damages to both layers.

In a further advantageous example the multilayer lighting sheet is composed of one LED layer and two diffusing optical layers, and wherein the mounting positions of the two diffusing optical layers are located at either side of the mounting position of the LED layer. In this example, with the multilayer lighting sheet fully unwound and protracted from the housing, the LED layer is sandwiched between the two optical layers, which are unwound at either side of the LED layer. With this example, it is possible to display and illuminate two diffusing optical layers simultaneously with one LED layer.

In yet a further example the retractable lighting fixture comprises at least one driver accommodated in the drum arranged for receiving a supply power and for driving the LED layer based on said received supply power.

In a particular example according to the disclosure, the at least one diffusing optical layer is provided at the first optical layer edge with an identification characteristic and a sensing element is provided near at least one of the first, second or further positions, the sensing element structured to sense the identification characteristic of the at least one diffusing optical layer, when mounted at either first, second or further positions.

The identification characteristic provided at the first optical layer edge can be a barcode (QR-code), a punch pattern, or a RFID tag, and can be sensed or detected by the sensing element mounted at one of the positions at the rotatable drum. As in a particular example, the sensing element is structured to control the driver in response to the identification characteristic of the at least one diffusing optical layer being sensed. Thus, an adaptive lighting fixture is presented, capable of adapting the light output of the LED layer and thus adapt the illuminance of the optical layer.

Preferably, the sensing element is accommodated in one of the grooves allowing a proper sensing of the identification characteristic once the free layer edge of the at least one optical layer is mounted in the corresponding groove.

Preferably, in an example according to the disclosure, the at least one diffusing optical layer is made from an at least partially light transmissive material.

In a further example, the layer surfaces of the LED layer and the at least one diffusing optical layer facing each other are structured to reflect visible light. Herewith light being emitted by the LED layer towards the optical layer and which is in part reflected back to the LED layer, is reflected back to the optical layer. This light recycling process improves the overall illuminance of the optical layer and decreases light spots on the optical layer.

In a detail of the above example, the layer surfaces of the LED layer and the at least one diffusing optical layer facing each other are provided with a reflective film.

In yet another advantageous example according to the disclosure, a second LED layer edge of the LED layer and a second optical layer edge of the diffusing optical layer are provided with one or more weight elements. Herewith an effective full unrolling of the multilayer lighting sheet is guaranteed and also stability is provided in for windy outdoor conditions.

The retractable lighting fixture may further comprise light shielding means structured to shield light emitted by the LED layer from exiting or leaking the multilayer lighting sheet along its longitudinal side edges from the space or gap between both the LED layer and the optical layer.

In an example the light shielding means are retractable mounted to the rotatable drum, or the light shielding means are mounted to and extend along the longitudinal side edges of the LED layer. In either example, light emitted by the LED layer is prevented from escaping the multilayer lighting sheet along its both longitudinal side edges. With the gap or space between both layers being closed, no disturbing direct light from the LEDs on the LED layer can be seen, and also the optical efficiency is increased, as well as the light uniformity.

According to a second aspect of the disclosure, a retractable lighting fixture is proposed, comprising a housing; an elongated drum rotatable over a length axis and accommodated in the housing; and a flexible LED layer sheet movable between a retracted position and a protracted position more than the retracted position, with the flexible LED layer sheet in the retracted position being at least partially retracted in one or more windings around the drum and with the flexible LED layer sheet in the protracted position being unwound from the drum and protracted via an exit position from the housing; and at least one diffusing optical layer having a first optical layer edge mounted at a first mounting position of the housing, the first mounting position being different from the exit position.

This example of a retractable lighting fixture allows to unwound the flexible LED layer sheet in its protracted position at any desired length dimension. Herewith the flexible LED layer sheet can be adapted to fit to the length of the optical layer, thus obtaining the optimal illumination of the information contained on the optical layer.

In a further example, the exit position is configured as an exit opening extending along the length axis of the housing, in particular configured as a slit-like exit opening.

Alternatively, the inventive retractable lighting fixture can be expressed as:.

The drum when accommodating the carrier, then can be considered as a housing, wherein the carrier inside the drum then is considered as being a drum.

The invention will now be discussed with reference to the drawings, which show in:.

For a proper understanding of the invention, in the detailed description below corresponding elements or parts of the invention will be denoted with identical reference numerals in the drawings.

<FIG>, which is denoted with PRIOR ART, describes a known example of a retractable lighting fixture or poster like display box, denoted with reference numeral <NUM>. The retractable lighting fixture <NUM> includes a housing <NUM> and a flexible multilayer lighting sheet <NUM> retractably retainable within the housing <NUM>. The multilayer lighting sheet <NUM> includes a LED layer <NUM> and an optical layer <NUM> abutting or laying over the LED layer <NUM>, when accommodated inside the housing <NUM>.

The LED layer <NUM> includes a plurality of LEDs <NUM> thereon and may optionally include electrical connections extending to the LEDs <NUM>. In alternative embodiments, the electrical connections may be provided to the LEDs <NUM> separate from the LED layer <NUM>. The LEDs <NUM> are all positioned such that a majority of light output therefrom is primarily directed toward the optical layer <NUM>. The optical layer <NUM> may be a flexible optical diffuser sheet, containing information for display and for illumination by the LED layer <NUM>. The optical layer <NUM> may additionally or alternatively include a phosphor in some embodiments to alter the color of light emitted there through.

The multilayer lighting sheet <NUM> is formed as a flexible multilayer lighting sheet foil composed of the LED layer <NUM> and the optical layer <NUM>, which can be rolled up on a roll or drum <NUM> for transport or storage. As such, the optical layer <NUM> and the LED layer <NUM> are jointly mounted with their respective free layer edges 22a and 21a at a joint mounting position <NUM>-<NUM> at the outer circumference 12a of the drum <NUM> (and their other free layer edges 22a-21b extending outside the housing <NUM>). This mounting configuration allows that the multilayer lighting sheet <NUM> is movable between a retracted position, wherein the multilayer lighting sheet <NUM> is more or less partially retracted in one or more windings around the rotatable drum <NUM> within the housing <NUM> and in a protracted position wherein the multilayer lighting sheet <NUM> is fully unwound from the rotatable drum <NUM> and protracted from the housing <NUM>.

This fully protracted position is depicted in <FIG>. Such poster like display boxes are used at events, such as conventions, or for promotions in retail environments, such as shops, galleries, showrooms, and the like. When unrolled, the flexible multilayer lighting sheet foil presents a display for illumination or advertisement/information purposes, with the optical layer <NUM> being illuminated by the activated LED layer <NUM>. For a proper illumination, the diffusing optical layer <NUM> needs to be spaced at an appropriate distance d from the LED layer <NUM>, in particular to minimize the appearance of a light-dot pattern from the activated LEDs <NUM> and/or may help mix light output from multiple colors of LEDs <NUM>.

In the example according to the prior art the LED layer <NUM> and the optical layer <NUM> of the multilayer lighting sheet <NUM> are in an expanded spaced relation to one another downstream of a pair of compression rollers 13a-13b and in a compressed relation to one another upstream of the compression rollers 13a-13b. When in the protracted orientation the LED layer <NUM> and the optical layer <NUM> are move away from each other and maintained in a desired spaced apart orientation by means of a spacer mechanism <NUM> present between both layers, here mechanical awning parts such as folding awning arms.

<FIG> depicts an example of the retractable lighting fixture according to the disclosure exhibiting a less complex and expensive construction as presently known in the art. The example according to the disclosure also allows for an easy exchange of the optical layer <NUM>, which is essential for a poster backlighting solution, with another optical layer <NUM> containing differentiation information to be displayed and illuminated.

The example of the retractable lighting fixture according to the disclosure is denoted with reference numeral <NUM> and also comprises a housing <NUM> provided with end caps 110a-110b at both its open housing ends and an elongated, rotatable drum <NUM> (not depicted) accommodated in the housing <NUM>. Please note that the housing <NUM> is a non-essential part of the several examples of the retractable lighting fixture according to the disclosure as described in this application. Similarly as in the prior art example of <FIG>, a multilayer lighting sheet <NUM> composed of a LED layer <NUM> and at least one diffusing optical layer <NUM> is accommodated around the drum <NUM> in one or more windings. The at least one optical layer <NUM> may be a flexible optical diffuser sheet, containing information for display and for illumination by the LED layer <NUM>.

In <FIG>, the multilayer lighting sheet <NUM> is depicted in the protracted position wherein the multilayer lighting sheet <NUM> is unwound from the elongated, rotatable drum <NUM> and protracted from the housing <NUM>. As such, the elongated drum <NUM> is rotatable along its longitudinal axis 120q. In this example the multilayer lighting sheet <NUM> is composed of one LED layer <NUM> and one diffusing optical layer <NUM>. In this protracted position both the LED layer <NUM> and the optical layer <NUM> are maintained in a desired spaced apart orientation, by a distance d measured between the outer, lowest free hanging layer edges 21b and 22b, respectively.

The protracted position or orientation of the LED layer <NUM> and the optical layer <NUM> is shown in more detail of <FIG>, depicted a schematic side view of the drum <NUM> of the example of the retractable lighting fixture <NUM>. Please note that schematic view does not necessarily shows the parts of the retractable lighting fixture <NUM> on scale, but merely is intended to disclose the functional features of this example.

In <FIG> the drum <NUM> has a cylindrical configuration having a diameter D and a longitudinal dimension, more or less similar to the longitudinal dimension of the housing <NUM>. The LED layer <NUM> is also provided with multiple LED elements <NUM> and has a first LED layer edge 21a which is mounted at the outer circumference 120a of the rotatable drum <NUM> at a first position, being indicated with reference numeral <NUM>-<NUM>. Similarly, the diffusing optical layer <NUM> containing the information to be displayed and illuminated by the LED layer <NUM>, has a first optical layer edge 22a, which is mounted at a second position, indicated with reference numeral <NUM>-<NUM>, at the outer circumference 120a of the rotatable drum <NUM>.

As shown in <FIG>, the first position <NUM>-<NUM> is located at some distance from the second position <NUM>-<NUM>, in particular the first position <NUM>-<NUM> is positioned at an arc length S1-<NUM> along the circumference 120a from the second position <NUM>-<NUM>. With both LED layer <NUM> and diffusing optical layer <NUM> being mounted at different positions <NUM>-<NUM> and <NUM>-<NUM> at the outer circumference 120a of the drum <NUM>, both layers <NUM>-<NUM> will be automatically spaced apart from each other at a distance d<NUM>-<NUM> measured between both free falling layer edges 21b and 22b, when unwound and protracted from the housing <NUM>. No additional spacer mechanism is required and due to the spacing d<NUM>-<NUM> thus created a correct and effective illumination of the information containing optical layer by means of the LED layer is achieved.

The spacing d<NUM>-<NUM> between both LED layer <NUM> and diffusing optical layer <NUM> can be considered being equal to the chord distance between both first and second positions <NUM>-<NUM> and <NUM>-<NUM> at the outer circumference 120a of the drum <NUM>. In this particular example of <FIG>, both first and second positions <NUM>-<NUM> and <NUM>-<NUM>, respectively, are located at opposite sides of the rotatable drum <NUM>, more or less at <NUM>°. The arc length s<NUM>-<NUM> is thus a semicircle and is equal to ½·π·D, with D being the diameter of the drum <NUM>. Similarly, the corresponding chord length or distance d<NUM>-<NUM> corresponding with the arc length s<NUM>-<NUM> defines the spacing between both layers in the fully unwound or unrolled, protracted orientation. Said spacing d<NUM>-<NUM> equals the diameter D of the drum <NUM>.

<FIG> shows another configuration example of the drum <NUM>' for use in a retractable lighting fixture <NUM> according to the disclosure, with the first position <NUM>-<NUM> being the mounting position for the free layer edge 21a of the LED layer <NUM> and another mounting positon <NUM>-<NUM> being the mounting position for the free layer edge 22a of the optical layer <NUM>. The other mounting positon <NUM>-<NUM> is also located at a distance from the first position <NUM>-<NUM>, which distance however differs from the example of <FIG>. In particular the first position <NUM>-<NUM> is positioned at an arc length s<NUM>-<NUM> along the circumference 120a from the further position <NUM>-<NUM>, which arc length s<NUM>-<NUM> corresponds with <NUM>°. When fully unwound and protracted from the housing <NUM> both LED layer <NUM> and diffusing optical layer <NUM> will be spaced apart from each other at a distance d<NUM>-<NUM>, again measured between both free falling layer edges 21b and 22b.

The spacing d<NUM>-<NUM> between both LED layer <NUM> and diffusing optical layer <NUM> is equal to the chord distance between both first and further positions <NUM>-<NUM> and <NUM>-<NUM> at the outer circumference 120a of the drum <NUM>, in this example of <FIG>, the arc length s<NUM>-<NUM> being a quarter circle equal to ¼·π·D, again with D being the diameter of the drum <NUM>.

Preferably, the arc length s between the mounting position of the free layer edge 21a of the LED layer <NUM> and the mounting position of the free layer edge 22a of the optical layer <NUM> may range between <NUM>°-<NUM>°, for example between <NUM>°-<NUM>° and in particular between <NUM>°-<NUM>°. Herewith specific spacing distances d, equal to the chord length of the respective arc length s, between the two layers <NUM>-<NUM> can be achieved in the fully unwound or unrolled, protracted orientation, thus achieving a desired illuminance of the optical layer <NUM> and hence an optimal visualization and presentation of the information contained thereon.

<FIG> shows a schematic example of a drum <NUM>" for use in a retractable lighting fixture <NUM> according to the disclosure with several distinct mounting positions denoted <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> for either free layer edge 21a-22a of the LED/optical layer <NUM>-<NUM>. The mounting positions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM> are located at the outer circumference 120a of the drum <NUM>" at angle orientations <NUM>°-<NUM>°-<NUM>°-<NUM>° and <NUM>° respectively.

For example, as shown in <FIG> and <FIG>, the several mounting positions (the first position <NUM>-<NUM>, second position <NUM>-<NUM> and further positions <NUM>-x, with the suffix x being <NUM>, <NUM>, <NUM>. etc.) are located at the outer circumference 120a of the drum <NUM>" at equidistant arc lengths from each other, for example at equidistant arc lengths of <NUM>° or <NUM>°. In <FIG> the mounting positions <NUM>-<NUM>/<NUM>-<NUM>/<NUM>-<NUM>/<NUM>-<NUM> are each positioned at equidistant arc lengths of <NUM>° (s = ¼·π·D), whereas in <FIG> the mounting positions <NUM>-<NUM>/<NUM>-<NUM>/<NUM>-<NUM> are each positioned at equidistant arc lengths of <NUM>° (s = <NUM>/<NUM>·π·D). Similarly, in <FIG> the mounting positions <NUM>-<NUM> and <NUM>-<NUM> are each positioned at equidistant semicircle arc lengths of <NUM>° (s = ½·π·D). These examples effectively present a retractable lighting fixture with a rotatable multi-spacing drum, allowing the multilayer lighting sheet <NUM> to be set up in the unwound or unrolled, protracted orientation with a spacing which can be selected in advance by mounting the LED layer <NUM> and the optical layer <NUM> in positions distanced by a pre-selected arc length.

Another example of a retractable lighting fixture according to the disclosure is depicted in <FIG> and denoted with reference numeral <NUM>. In this embodiment the drum <NUM> is accommodated in the housing <NUM>, which in turn can be shielded at its open free ends with end caps 110a-110b. The drum <NUM> comprises at its outer circumference 120a a first groove <NUM>-<NUM> located at a position, which is denoted as the first position <NUM>-<NUM> in the several <FIG>. The drum <NUM> also comprise a second groove, which is denoted with reference numeral <NUM>-<NUM>, as the groove is located at the outer circumference 120a of the drum <NUM>‴ at a position, which is denoted with reference numeral <NUM>-<NUM> in for example <FIG>. Both grooves <NUM>-<NUM> and <NUM>-<NUM> are distanced from each other by an arc length s<NUM>-<NUM> which is equal to <NUM>°.

The drum <NUM>‴ accommodates the several windings of the multilayer lighting sheet <NUM>, wherein the first groove <NUM>-<NUM> accommodates the free LED layer edge 21a of the LED layer <NUM> and the first groove <NUM>-<NUM> accommodates the free optical layer edge 22a of the optical layer <NUM>. This allows the LED and optical layers <NUM>-<NUM> to be easily inserted and secured to the rotatable drum <NUM>‴.

The grooves <NUM>-<NUM> and <NUM>-<NUM> extend in the longitudinal direction of the drum <NUM>‴ as shown in <FIG>, thus allowing a proper accommodating of the free layer edge of the LED layer <NUM> and the optical layer <NUM> over the entire layer width in their respective groove. Also, with the several grooves present in the outer circumference 120a of the rotatable drum <NUM> and the free edges 21a or 22b of the layer mounted therein an improved rolling up and down of multilayer lighting sheet <NUM> is achieved without the risk of folds, greases, wrinkles or damages to both layers.

In an improvement of the disclosure, shown in <FIG>, the rotatable drum <NUM> at its outer circumference 120a comprises at least one further groove at a further position different from the first and second position. In <FIG> the further groove is denoted with reference numeral <NUM>-<NUM> and is located at position <NUM>-<NUM> as shown in <FIG>. The further groove <NUM>-<NUM> has an arc length s<NUM>-<NUM> with the first position/groove <NUM>-<NUM>/<NUM>/<NUM> of <NUM>° (s<NUM>-<NUM> = <NUM>/<NUM>·π·D) and has an arc length s<NUM>-<NUM> with the second position/groove <NUM>-<NUM>/<NUM>/<NUM> of <NUM>°-<NUM>°=<NUM>° (s<NUM>-<NUM> ≈ ¼·π·D). This allows to mount the LED layer <NUM> and optical layer <NUM> to the drum <NUM>‴ at several different positions, allowing an easy exchange of one of the layers, but also to select the correct spacing d<NUM>-<NUM>, d<NUM>-<NUM> or d<NUM>-<NUM> defined by the chord corresponding with the arc length s<NUM>-<NUM> or s<NUM>-<NUM> or s<NUM>-<NUM> between the two selected mounting positions for the LED layer <NUM> and the optical layer <NUM>, respectively.

The possibility to select the correct (chord) spacing between the layers <NUM> and <NUM> allows for a simple adjustment or selection of the proper, desired illuminance of the optical layer <NUM> using the LED layer <NUM>. It is noted that <FIG> depicts three grooves <NUM>-x as a mere example, and that the drum <NUM> can be provided with multiple grooves <NUM>-x (with x ∈ [<NUM>. N], N being a natural number) with any desired arc length orientation as depicted in <FIG>.

The drum <NUM> can be made hollow (in part) to accommodate one or more LED drivers <NUM> for receiving a supply power and for driving the LED layer <NUM> based on said received supply power. The supply power (not depicted) can also be retained within the drum <NUM> and can be embodied as a (rechargeable) or otherwise replaceable battery pack. In some embodiments the one or more LED drivers <NUM> can be electrically coupled to a mains power supply via suitable circuitry (printed circuit board circuitry). Also a solar panel and/or other external power supply may be utilized as a supply power for the driver <NUM>. In alternative embodiments the supply power may be located outside of the drum <NUM> or housing <NUM>.

For a proper and secure mounting of the free layer edges 21a-22a of both the LED layer <NUM> and the optical layer <NUM> in either groove present in the drum <NUM>-<NUM>'-<NUM>"-<NUM>‴-120ʺʺ clamping means can be accommodated in each groove. The clamping means can constitute a narrow inner space of the groove, such as shown with groove <NUM>-<NUM>, thus clamping the free layer edge 21a of the LED layer <NUM> with its both layer sides against the walls of the groove <NUM>-<NUM>. This clamping mechanism also guarantees a proper electrical contact between the driver <NUM> and electrical connections (not shown) present in the groove <NUM>-<NUM>, which electrically connect with electrical connections present on the LED layer <NUM>, which in turn extending in the LED layer <NUM> towards the several LEDs <NUM> for energizing the latter.

In a particular example according to the disclosure, the clamping means may constitute ball clamp mechanism comprising multiple balls or a ball rod <NUM>-<NUM> and <NUM>-<NUM> accommodated in each groove <NUM>-<NUM> and <NUM>-<NUM> for holding the free layer edge 22a of the optical layer in a clamping fashion the groove <NUM>-<NUM> or <NUM>-<NUM>. See also <FIG>.

Alternatively, each groove <NUM>-x can be structured as a small slit through the circumference 120a of the drum <NUM>. Each free, first layer edge 21a-22a of either LED layer <NUM> and diffusing optical layer <NUM> can be provided with a thickened ridge. By sliding the layers <NUM>-<NUM> in their respective slit, the thickened ridge will extend inside the drum and behind the slit thus preventing a release of the respective layer.

The optical layer <NUM> may be provided at its free optical layer edge 22a with an identification characteristic denoted with 22z. The identification characteristic 22z provided at the optical layer edge 22a can be a barcode (QR-code), a punch pattern, or a RFID tag, and can identify the optical layer e.g. as to its optimal illumination settings. Preferably, near each of the grooves <NUM>-x (with x ∈ [<NUM>. N], N being a natural number) a sensing element <NUM>-<NUM> (<NUM>-<NUM>) can be provided, either in the respective groove as shown in <FIG> or inside the drum <NUM>‴ next to each groove as shown in <FIG>.

The sensing element <NUM>-<NUM> (<NUM>-<NUM>) can sense the identification characteristic 22z of the diffusing optical layer <NUM>, when the optical layer <NUM> is mounted with its free layer edge 22a at either mounting position sec. in either groove. As in a particular example, the identification characteristic 22z defines the optimal illumination settings for the associated optical layer, the sensing element <NUM>-x (with x ∈ [<NUM>. N], N being a natural number) can control the driver <NUM> in response to the identification characteristic 22z of the diffusing optical layer being sensed. For example, with the identification characteristic 22z characterizing the optimal illumination settings for the associated optical layer <NUM>, an adaptive lighting fixture <NUM> can be used, capable of adapting the light output of the LED layer <NUM> and thus optimally adapt the illuminance of the optical layer <NUM> mounted in the groove.

To facilitate effective full unrolling of the multilayer lighting sheet <NUM> and also to maintain stability for windy outdoor conditions the second LED layer edge 21b of the LED layer <NUM> and the second optical layer edge 22b of the diffusing optical layer <NUM> are provided with one or more weight elements, for example as weight rod extending over the full width of the layers <NUM>-<NUM> and worked in the material of the layers near their layer edges 21b-22b.

In <FIG> and <FIG> another example of a retractable lighting fixture <NUM> according to the disclosure is shown. <FIG> and <FIG> depict a specific configuration of the multilayer lighting sheet <NUM>, which is composed of one LED layer <NUM>' and two diffusing optical layers <NUM><NUM> and <NUM><NUM>. The associated drum <NUM>"" of this example is provided with three mounting positions, denoted with <NUM>-<NUM>, <NUM>-<NUM> and <NUM>-<NUM>. Similarly as depicted in <FIG>, the mounting positions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> are structured as grooves <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> in the outer circumference 120a of the drum <NUM>"" and extending in longitudinal direction thereof.

In this example, with the multilayer lighting sheet <NUM> fully unwound from the drum <NUM>"" and protracted from the housing, the LED layer <NUM>' is sandwiched between the two diffusing optical layers <NUM><NUM> and <NUM><NUM>, which are unwound at either side of the LED layer <NUM>'. The LED layer <NUM>' is a so-called dual sided LED layer, having two LED groups, each comprising a plurality of LEDs <NUM>-<NUM> and <NUM>-<NUM>, and with each group of LEDs <NUM>-<NUM>/<NUM>-<NUM> being provided on either surface 21f1 and 21f2. Each layer 21f1-21f2 may optionally include electrical connections extending to each group of LEDs <NUM>-<NUM>/<NUM>-<NUM>. In alternative embodiments, the electrical connections may be provided to the LEDs separate from the LED layer <NUM>'.

The two groups LEDs <NUM>-<NUM>/<NUM>-<NUM> of the dual sided LED layer <NUM>' are all positioned such that a majority of light output therefrom is primarily directed toward the each optical layer <NUM><NUM> and <NUM><NUM> facing either LED layer surface 21f1 and 21f2. With this example, it is possible to display and illuminate two diffusing optical layers <NUM><NUM> and <NUM><NUM> simultaneously with one dual sided LED layer <NUM>'.

In a further example, the retractable lighting fixture incorporating a drum <NUM>‴‴ with a sandwiched multilayer lighting sheet <NUM>-<NUM>'-<NUM><NUM>-<NUM><NUM> of <FIG> and <FIG>, is preferably powered using two drivers <NUM> accommodated in the drum <NUM>"", for separately energizing each group of LEDs <NUM>-<NUM> and <NUM>-<NUM> provided on either surface 21f1-21f2 of the dual sided LED layer.

Accordingly, with reference to the examples of <FIG> and <FIG>, also in <FIG> and <FIG> near each mounting position <NUM>-<NUM> and <NUM>-<NUM> or in each corresponding groove <NUM>-<NUM> and <NUM>-<NUM> a sensing element <NUM>-<NUM> and <NUM>-<NUM> can be accommodated, for sensing the identification characteristic 22z of either diffusing optical layer <NUM><NUM> and <NUM><NUM> mounted with their first layer edge 22a1 and 22a2 at that mounting position sec. in either groove.

Similarly, as the identification characteristic 22z of the corresponding diffusing optical layer <NUM><NUM> and <NUM><NUM> define the optimal illumination settings for the associated optical layer, the sensing element <NUM>-<NUM> and <NUM>-<NUM> can control the driver <NUM> or either separate driver associated with one of the LED groups <NUM>-<NUM>/<NUM>-<NUM> in response to the identification characteristic 22z of the diffusing optical layer <NUM><NUM> and <NUM><NUM> being sensed. Herewith, the illuminance of two optical layers <NUM><NUM> and <NUM><NUM> sandwiching the dual sided LED layer <NUM>' can thus be optimally adapted by one dual sided LED layer <NUM>'.

With reference to the several configurations of the mounting positions in <FIG>, the arc lengths s<NUM>-<NUM>, s<NUM>-<NUM> and s<NUM>-<NUM> between the several mounting positions <NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM> can be arbitrary chosen. In the example of <FIG>, the mounting position <NUM>-<NUM> serves to accommodate the first layer edge 21a of the LED layer <NUM>', whereas the mounting positions <NUM>-<NUM> and <NUM>-<NUM> serve to accommodate the respective first layer edges 22a1 and 22a1 of the two diffusing optical layers <NUM><NUM> and <NUM><NUM>, respectively. From <FIG> and <FIG> it is clear that the mounting positions <NUM>-<NUM> and <NUM>-<NUM> for the two diffusing optical layers <NUM><NUM> and <NUM><NUM> are located at either side of the mounting position <NUM>-<NUM> for the LED layer <NUM>'.

In other words, in this example, the mounting positions <NUM>-<NUM> and <NUM>-<NUM> are located at equidistant, yet opposite directed, arc lengths from the centrally located mounting position <NUM>-<NUM>. For example, with the mounting position <NUM>-<NUM> located at <NUM>°/<NUM>° (see also <FIG> and <FIG>) the mounting position <NUM>-<NUM> can be positioned at <NUM>°-<NUM>°-<NUM>°-<NUM>°-<NUM>° and the mounting position <NUM>-<NUM> at corresponding equidistant, yet opposite positions of <NUM>°-<NUM>°-<NUM>°-<NUM>°-<NUM>°. Alternatively, the drum 120ʺʺ can be provided with one centrally oriented mounting position <NUM>-<NUM> for the dual sided LED layer <NUM>' and several mounting positions at either side of the mounting position <NUM>-<NUM>, equidistant or non-equidistant, thus allowing a more versatile drum configuration where the two diffusing optical layers <NUM><NUM> and <NUM><NUM> of the multilayer lighting sheet <NUM>-<NUM>'-<NUM><NUM>-<NUM><NUM> can be mounted at different positions relative to the central mounting position <NUM>-<NUM> either equidistant or if needed at different arc length positions.

<FIG> discloses yet another example of the retractable lighting fixture <NUM> according to the disclosure. Reference numerals 201a1-201a2-201b are elements of light shielding means <NUM>, which are intended to shield light emitted by the LED layer <NUM> from exiting or leaking the multilayer lighting sheet <NUM> from the space or gap d (see <FIG>) between both the LED layer <NUM> and the optical layer <NUM> pass the longitudinal side edges 21c1-22c1/21c2-22c2 and the bottom layer edges 21b-22b of the LED layer <NUM> and the optical layer <NUM>, respectively.

In an example the light shielding means <NUM> are retractable mounted to the elongated drum <NUM>, which is rotatable around its longitudinal axis 120q. In another embodiment the light shielding means <NUM> and in particular the shielding elements or sheets 201a1-201a2-201b are mounted to and extend along the longitudinal side edges 21c1-21c2 and to the bottom layer edge 21b of the LED layer <NUM>, for example by means of by means of Velcro, magnetic strips or zip locks. Herewith, light emitted by the LED layer <NUM> is prevented from escaping the multilayer lighting sheet <NUM> along its both longitudinal side edges. With the gap or space d between both layers <NUM>-<NUM> being closed, no disturbing direct light from the LEDs <NUM> on the LED layer <NUM> can be seen, and also the optical efficiency is increased, as well as the light uniformity.

The light shielding means <NUM> (the shielding elements or sheets 201a1-201a2-201b) can also be used with the dual sided LED layer <NUM>' of <FIG> and <FIG>. When implemented with the dual sided LED layer <NUM>' of that example the shielding elements or sheets 201a1-201a2-201b are mounted in a similar manner to the dual sided LED layer <NUM>' and extend in two opposite orientations along the longitudinal side edges 21c1-21c2 and to the bottom layer edge 21b of the LED layer <NUM>'. The shielding elements or sheets shield both spacings d1 and d2 formed between the optical layers <NUM><NUM> and <NUM><NUM> and the dual sided LED layer <NUM>'. The mounting of the shielding elements or sheets with the dual sided LED layer <NUM>' and/or the optical layers <NUM><NUM> and <NUM><NUM> can be achieved in a similar manner, for example by means of by means of Velcro, magnetic strips or zip locks.

Similarly, light emitted in both directions by the dual sided LED layer <NUM>' towards the optical layers <NUM><NUM> and <NUM><NUM> is prevented from escaping the multilayer lighting sheet <NUM> along its both longitudinal side edges. With the gaps or spaces d1-d2 being closed, no disturbing direct light from the LEDs <NUM>-<NUM> and <NUM>-<NUM> can be seen, and also the optical efficiency is increased, as well as the light uniformity.

When retracting the flexible multilayer lighting sheet <NUM> back within the housing <NUM> by winding it in several windings on the drum <NUM> the shielding elements 201a1-201a2-201b can either be removed from the (dual sided) LED layer <NUM>-<NUM>' (due to the releasable Velcro, magnetic strips or zip locks connections) or alternatively the shielding elements 201a1-201a2-201b can be folded again the (dual sided) LED layer <NUM>-<NUM>' and retracted together the multilayer lighting sheet <NUM> the within the housing <NUM>.

In all examples as disclosed in the Figures, the diffusing optical layer <NUM> (or optical layers <NUM><NUM> and <NUM><NUM>) can be made from an at least partially light transmissive material. Additionally the layer surfaces 21f (single layer version of e.g. <FIG>, <FIG>, <FIG> and <FIG>) and 21f1-21f2 (dual layered version of <FIG> and <FIG>) of the LED layer <NUM> (<NUM>') and the layer surfaces 22f (22f1-22f2) of the diffusing optical layer <NUM> (<NUM><NUM>-<NUM><NUM>) facing each other are structured to reflect visible light. Herewith light being emitted by the LED layer <NUM> (<NUM>') towards the optical layer(s) <NUM> (<NUM><NUM>-<NUM><NUM>) and which is in part reflected back to the LED layer <NUM> (<NUM>'), is reflected back to the optical layer(s) <NUM> (<NUM><NUM>-<NUM><NUM>). This light recycling process improves the overall illuminance of the optical layer and decreases light spots on the optical layer. In a detail of the above example, the layer surfaces of the LED layer <NUM>(<NUM>') and that of the diffusing optical layer <NUM>(<NUM><NUM>-<NUM><NUM>), which facing each other are provided with a reflective film. See in particular in <FIG>, <FIG>, and <FIG>).

The film or foil applied to the layer surfaces 21f (21f1-21f2) and 22f(22f1-22f2) could be made from polymers like reflective PC, PMMA, PET, PS, PP. In another example the film or foil could be a specular layer with a metal, for example aluminium added or deposited on the layers <NUM> (<NUM>') and <NUM> (<NUM><NUM>-<NUM><NUM>).

<FIG> and <FIG> depict another example of the retractable lighting fixture according to the disclosure. Also this example exhibits a less complex and expensive construction as presently known in the art. The example according to the disclosure in particular allows for an easy exchange of the optical layer, in <FIG> and <FIG> also denoted with reference numeral <NUM>, which is essential for a poster backlighting solution, with another optical layer <NUM> containing differentiation information to be displayed and illuminated. In addition, the example of the retractable lighting fixture of <FIG> and <FIG> allows for unwinding the flexible LED layer sheet <NUM> from the drum <NUM> and from the housing <NUM> at any desirable length.

In <FIG> and <FIG> the other example of the retractable lighting fixture according to the disclosure is denoted with reference numeral <NUM>. It also comprises a housing <NUM> provided with end caps 110a-110b at both its open housing ends as shown in <FIG>. Furthermore, an elongated drum <NUM> which is rotatable over a length axis 1200q is accommodated in the housing <NUM>. A flexible single LED layer sheet <NUM> is at least partially retracted in one or more windings around the drum <NUM>, in a so-called retracted position.

Similar as with the first example of the disclosure, the LED layer <NUM> has a first LED layer edge 21a, which is mounted or clamped in a groove <NUM> present in the outer circumference 1200a and extending in the elongated direction of the elongated drum <NUM>. The flexible single LED layer sheet <NUM> is movable between the retracted position and a protracted position. In the protracted position, the flexible single LED layer sheet <NUM> exhibits an orientation in which it has an elongated dimension longer than in the retracted position.

In particular, in the protracted position, one or more windings of the flexible LED layer sheet <NUM> are being unwound from the drum <NUM>, such that the flexible single LED layer sheet <NUM> protracts from an exit position <NUM>-<NUM>' of the housing <NUM>, as depicted in the sectional view of <FIG>. The exit position <NUM>-<NUM>' can be configured as an exit opening extending along the length axis of the housing <NUM>. In <FIG> and <FIG>, the exit opening is configured as a slit-like opening, having an opening width (or height) more or less conformal to the thickness of the flexible LED layer sheet <NUM>. This allows the flexible LED layer sheet <NUM> to exit the housing <NUM>, when being unwound from the drum <NUM>.

Similarly as the example depicted in <FIG> and <FIG> the flexible single LED layer <NUM> is also provided with multiple LED elements <NUM>, which serve to illuminate an optical layer <NUM>, which may contain information for display. In <FIG> and <FIG> the optical layer <NUM> may be a flexible optical diffuser sheet, containing information for display and for illumination by the LED layer <NUM>. The optical layer <NUM> is mounted with its free layer edge 22a, either through a clamping mechanism or other type of mechanism, e.g. using magnets, at a first mounting position <NUM>-<NUM>' at the outer circumference of the housing <NUM>.

In the protracted position of the flexible LED layer <NUM>, the first mounting position <NUM>-<NUM>' differs from the exit position <NUM>-<NUM>' through which the flexible LED layer <NUM> protracts. As shown in <FIG>, the first mounting position <NUM>-<NUM>' and the exit position <NUM>-<NUM>' are located at opposite sides of the circumference of the housing <NUM>, e.g. at an arc length of approximately <NUM>°. As shown in <FIG>, both layers <NUM>-<NUM> are spaced apart from each other at a distance d1. No additional spacer mechanism is required and with this configuration, the protracted length of the flexible LED layer <NUM> being unwound from the drum <NUM> can be adapted to fit to the length of the optical layer <NUM>. Herewith, the optimal illumination of the information contained on the optical layer <NUM> can be achieved.

In <FIG> the elongated drum <NUM>-<NUM>' has a cylindrical configuration having a diameter and a longitudinal dimension, more or less similar to the longitudinal dimension of the housing <NUM>.

In <FIG> - combined with <FIG> - another example is depicted, more or less similar as the example of <FIG> and <FIG>, with one LED layer <NUM>' and two diffusing optical layers <NUM><NUM> and <NUM><NUM>. In <FIG> (and <FIG>) the example of the retractable lighting fixture according to the disclosure is denoted with reference numeral <NUM>'. It also comprises a housing <NUM>' provided with end caps 110a-110b at both its open housing ends as shown in <FIG>. Furthermore, an elongated drum <NUM> which is rotatable over a length axis 1200q is accommodated in the housing <NUM>'. A flexible LED layer sheet <NUM>' is partially retracted in one or more windings around the drum <NUM>, in the so-called retracted position and is mounted or clamped with its free layer edge 21a in the groove <NUM> provided in the outer circumference of the elongated and rotatable drum <NUM>.

The LED layer <NUM>' is a so-called dual sided LED layer, having two LED groups, each comprising a plurality of LEDs <NUM>-<NUM> and <NUM>-<NUM>, and with each group of LEDs <NUM>-<NUM>/<NUM>-<NUM> being provided on either surface 21f1 and 21f2. Each layer 21f1-21f2 may optionally include electrical connections extending to each group of LEDs <NUM>-<NUM>/<NUM>-<NUM>. In alternative embodiments, the electrical connections may be provided to the LEDs separate from the LED layer <NUM>'.

The two diffusing optical layers <NUM><NUM> and <NUM><NUM> may both contain different information to be displayed and illuminated simultaneously by the LED layer <NUM>'. They are both mounted with their respective free, first optical layer edge 22a1 and 22a2 are different first and second mounting positions <NUM>-<NUM>' and <NUM>-<NUM>', respectively. Both first and second mounting positions <NUM>-<NUM>' and <NUM>-<NUM>' are positioned at the outer circumference of the housing <NUM>' and differ from each other but also differ from the exit position <NUM>-<NUM>' at which the protracted dual LED layer sheet <NUM>' exits the housing <NUM>'. Thus, different gaps or spaces d1-d2 between each diffusing optical layers <NUM><NUM>-<NUM><NUM> and the LED layer <NUM>' is created and the illuminance of two optical layers <NUM> and <NUM> sandwiching the dual sided LED layer <NUM>' can thus be optimally adapted by one dual sided LED layer <NUM>'.

The drum <NUM>-<NUM>' of both examples of <FIG>, <FIG> and <FIG> can be made hollow (in part) to accommodate one or more LED drivers <NUM> for receiving a supply power and for driving the (dual) LED layer <NUM> (<NUM>') based on said received supply power.

Both examples of <FIG>, <FIG> and <FIG> can also be equipped with the light shielding means <NUM> as shown in relation to <FIG>, which light shielding means <NUM> are intended to shield light emitted by the (dual) LED layer <NUM>-<NUM>' from exiting or leaking from the space or gap d1 and d2 (see <FIG>) between both the (dual) LED layer <NUM> (<NUM>') and the optical layers <NUM> (<NUM><NUM>-<NUM><NUM>).

In a similar manner as disclosed with reference to the examples in <FIG>, the optical layers <NUM> (<NUM><NUM>-<NUM><NUM>) may be provided at their free optical layer edges 22a (22a1-22a2) with an identification characteristic denoted with reference numeral 22z (see <FIG> and <FIG>). The identification characteristic provided at the optical layer edges can be a barcode (QR-code), a punch pattern, or a RFID tag, and can identify the optical layer e.g. as to its optimal illumination settings. Similarly, sensing elements (not shown) can be provided at the housing <NUM>-<NUM>', either positioned at or worked in the outer circumference of the housing <NUM>-<NUM>' at the respective first and second mounting position <NUM>-<NUM>' and <NUM>-<NUM>'.

Claim 1:
A retractable lighting fixture (<NUM>), comprising:
an elongated drum (<NUM>,<NUM>',<NUM>") rotatable over a length axis (1200q); and
a flexible multilayer lighting sheet (<NUM>) movable between a retracted position and a protracted position more than the retracted position, with the multilayer lighting sheet in the retracted position being at least partially retracted in one or more windings around the drum and with the multilayer lighting sheet in the protracted position being fully unwound from the drum;
the multilayer lighting sheet being composed of at least one LED layer (<NUM>) and at least one diffusing optical layer (<NUM>), the at least one LED layer having a first LED layer edge (21a) mounted at a first mounting position (<NUM>-<NUM>) of the drum characterised the at least one diffusing optical layer having a first optical layer edge (22a) mounted at a second mounting position (<NUM>-<NUM> to <NUM>-<NUM>) of the drum, the first mounting position being located at an arc length (s<NUM>-<NUM>) from the second mounting position