TECHNICAL FIELD

[0001] The invention relates to a device for fastening a screen in a greenhouse or glasshouse, on a screen installation, and to a greenhouse or glasshouse provided with such a screen installation. Furthermore, the invention relates to a method for fastening a screen to a structure by means of the device. STATE OF THE ART

[0002] Devices for fastening a screen to a support structure of a greenhouse or glasshouse are known. US patent document US 4,665,670 describes a clamping device for fixing one or more screens of a flexible polymer material. Two such flexible screens may, for example, be used to form a translucent roof of a greenhouse. The known clamping device comprises two elongate profiled sections which are configured so as to mutually engage, with an intermediate space for clamping the one or more screens. In order to be able to achieve this clamping effect, the two profiled sections are provided with a number of curved and mating ducts and ridges. This known clamping device has the drawback that the thickness of the clamped screens plays a significant part with regard to the reliability of the clamping action: an insufficient screen thickness may result in excessive play between the profiled sections, while an excessive screen thickness will adversely affect de curvature and thus the mutual engagement of the ducts and ridges. A further drawback of the known device is the fact that it is only suitable for absorbing screen tensile forces in specific directions. If the screens are subjected to tensile forces which are sufficiently strong and are directed virtually opposite to the fixing direction of the two profiled sections, there is a significant risk of the known clamping device decoupling, resulting in an unwanted detachment of the screens.

[0003] It is therefore desirable to provide a fastening device by means of which a screen can be fixed to a supporting structure of a greenhouse or glasshouse in a robust and relatively simple manner. BRIEF DESCRIPTION OF THE INVENTION

[0004] According to a first aspect, the invention provides a fastening device for fastening a screen to a structure, comprising a profile element and a retaining lace. The profile element is provided with a chamber that extends through the profile element in a longitudinal direction and is configured to enclose a strip-shaped part of the screen. The profile element also comprises a longitudinal opening which extends along a side of the profile element in a longitudinal direction and forms a passage between the chamber and an outer side of the profile element. The profile element also comprises an introduction opening which is directly connected to the chamber. The retaining lace is slideable into the chamber, independently with respect to the screen through the introduction opening and substantially along the longitudinal direction, from a free position in which the retaining lace is situated entirely outside the chamber to an enclosed position in which the retaining lace is received in the chamber to fix the strip-shaped screen part therein.

[0005] In the present application, the term "screen", in its broadest sense, refers to a sheet-shaped element which may have one or more climate-regulating functions, including sunblind, darkening, moisture regulation, flow barrier and/or thermal insulation. The term screens here inter alia includes films/foils, cloths (e.g. of the woven or knitted type), mats, film/foil web screens, etc.

[0006] In connection herewith, the structure may, for example, form a support frame of a greenhouse or glasshouse, and the profile element forms part of a screen installation for fastening a climate-regulating screen to this support frame. Such a climate-regulating screen may be arranged so as to be fixed as well as to be controllably movable (for example retractable and extendable).

[0007] Furthermore, such a climate-regulating screen may be fitted in various shapes and/or orientations. Such a screen may be arranged, for example, in a horizontal orientation (for example a covering screen), in a vertical orientation (for example a wall screen), in a slanting orientation (for example a downward outer wall or a cavity- forming roof screen), or in a curved shape (such as a single-layered or double- layered arch-shaped greenhouse roof).

[0008] However, the structure may also be configured differently. The structure may form part of, for example, a pulling mechanism for retracting a screen via longitudinal sides in a spanning mechanism with rails. This pulling mechanism may be provided, for example, with a central pull cable which is connected to the profile element of the fastening device according to the first aspect of the invention by means of forked cables. Alternatively, the central pull cable may also be connected to the profile element via a triangular screen flap. The triangular screen flap may, for example, be made from a sufficiently strong film/foil, canvas, mat, textile, or similar material, which is able to transfer the retraction tensile forces of the central pull cable to the profile element.

Fastening the triangular screen flap to the profile element may be effected in a known manner. The screen flap may be provided with a fixed guide lace, for example along a base side, and the profile element may be provided with a further chamber, which runs parallel with the chamber, and in which the screen flap with guide lace can be accommodated. Other configurations of the pulling mechanism are possible, in particular for the coupling between pull cable(s) and profile part. Irrespective of the type of coupling between pull cables(s) and profile part, the screen may be coupled to the profile element along a strip- shaped screen part situated at the front, using the retaining lace. As a result thereof the pulling force exerted by the central pull cable via the forked cables or triangular screen flap and via the profile element can be transferred to the screen, so that the screen can be retracted along the rails of the spanning mechanism. After the screen has been retracted, the coupling between, on the one hand, the retracted screen and, on the other hand, the profile element and the retaining lace, can simply be removed, after which the profile element and retaining lace can be re-used for coupling the pulling mechanism to another screen.

[0009] The retaining lace in the fastening device according to the first aspect of the invention is formed as an elongate, slightly flexible element, which is formed in such a way that it can be accommodated inside the chamber in the longitudinal direction. The flexible retaining lace may for example be formed by a flexible cord, hose, hollow tube, rope, or strip. Preferably, the longitudinal ends of the retaining lace are flexible so they can be bent towards each other. This makes it possible to roll up the retaining lace around an axis along a transverse direction. This facilitates transportation and storage of the retaining lace.

[0010] The retaining lace can be retracted, independently from the screen, into the chamber via the introduction opening of the profile element in order to achieve the enclosed position. The term "independently retractable" implies that the retaining lace does not comprise any fastening means for directly fixing the retaining lace to the screen, in case the retaining lace and the screen are outside the chamber. The screen is thus not directly attached to the retaining lace, for example via stitching, gluing, fusing, stapling, embedding, weaving and the like.

[0011] The introduction opening may for example be configured as an end-side opening provided on a longitudinal end of the profile element, or as an intermediate opening which forms a local interruption (for example enlargement) of the longitudinal opening on the side of the profile element.

[0012] Prior to placing the retaining lace, the screen may already be positioned in the profile element in such a way that the strip-shaped screen part is enclosed by the chamber, although possibly not yet fixed therein. This is, however, not required. Alternatively, the screen may only be positioned against the profile element, without the strip-shaped screen part being enclosed by the chamber, before placement of the retaining lace. In this case, the retaining lace may be provided with means to force/push the strip-shaped screen part into the chamber, while drawing the retaining lace into the chamber. In both cases, the strip-shaped screen part will be fixed inside the chamber during retraction of the retaining lace, starting from the front longitudinal end of the lace and further, similar to the action of a zip. It is not necessary for the screen to be provided with a dedicated guide lace for effectuating fixing onto the device. In this case, the term "dedicated guide lace" indicates a guide lace which has already been fixed to the screen beforehand, for example by manufacturing, gluing, incorporating, and the like. Fixing a dedicated guide lace to the screen by manufacturing or other labour-intensive methods may be dispensed with (if desired).

[0013] Here, the term "enclosed position" (also pertaining to the retaining lace) implies that the retaining lace only has a very limited motional freedom after it has been accommodated inside the chamber, at least in the transverse directions at right angles to the longitudinal direction. If desired, the retaining lace in the enclosed position may be rotatable or movable in translation in the transverse directions along relatively small distances and/or angles, provided this does not result in the retaining lace exiting the longitudinal opening of the chamber.

[0014] The retaining lace may also be removable independently from the screen through the introduction opening of the profile element, from the enclosed position back to the free position. This is, however, not required. Alternatively or in addition, the retaining lace may also be removable independently from the screen through a remote outlet opening of the profile element, from the enclosed position back to the free position. The outlet opening may be configured, for example, as a head-end opening provided at an opposite longitudinal end of the profile element, or as a further intermediate opening which forms a local interruption (for example enlargement) of the longitudinal opening.

[0015] In order to facilitate retraction of the retaining lace along the longitudinal direction through the chamber of the profile element, the retaining lace may be provided with or coupled to an engagement member, which is provided for this purpose at or near a longitudinal end. Such an engagement member preferably comprises a structure having a width that is smaller than a width in the first transverse direction of the longitudinal opening in the profile element. As a result thereof, a component of this structure may project in a second transverse direction outward of the chamber of the profile element, while the retaining lace (or the major part thereof) remains accommodated in the chamber.

[0016] According to an embodiment, the longitudinal opening of the fastening element is delimited in a first transverse direction, and the retaining lace comprises a narrow section in the first transverse direction at or near a longitudinal end, in such a way that the retaining lace, in the enclosed position, may partially project through the longitudinal opening out of the chamber of the profile element, at the location of the narrow section.

[0017] Here, the term "longitudinal end" is understood to mean an end of the retaining lace, viewed in the longitudinal direction. The narrow section may be formed with a continuously curved edge profile without a sharp transition. The narrow section may be formed at the respective longitudinal end of the retaining lace, so that the resulting narrowed part itself forms the end of the retaining lace. Alternatively, the narrow section may be formed near the respective longitudinal end of the retaining lace, in which case the actual end of the retaining lace may be configured as a lace segment part which is wider than a width of the longitudinal opening. This wider lace segment may form, for example, a handle and/or a pulling eye or comprise another kind of fastening element. Thus, the retaining lace in the enclosed position can project from the profile element through the longitudinal opening at the location of the narrow section, while the handle or pulling eye can project outside the chamber while the rest of the retaining lace can remain inside the chamber.

[0018] According to an embodiment, the fastening device comprises a forerunner. This forerunner is provided with a sliding body which can be accommodated in a displaceable manner inside the chamber of the profile element, and with a fastening element situated at an end of the sliding body, and configured for fastening the forerunner to a longitudinal end of the retaining lace. The forerunner is configured to slide the retaining lace from the free position via the introduction opening along the longitudinal direction through the chamber.

[0019] The forerunner may comprise a handle which is connected to the sliding body. The handle has a width which allows it to project through the longitudinal opening of the chamber to the outside. To this end, the handle may (at least locally) be narrower than a width of the longitudinal opening of the profile element. The forerunner may, for example, be integrally formed with a handle, a sliding body, and a fastening element, which together form a single body. Alternatively, the handle, the sliding body, and the fastening element of the forerunner may be made from an assembly of separate components. According to yet another possibility, the forerunner may be made from a bent wire product with a wire diameter which is smaller than the width of the longitudinal opening of the profile element. Forerunners made from a combination of the abovementioned components are also possible.

[0020] In addition, embodiments of the forerunner are conceivable in which the sliding body is provided with a coupling element instead of or in addition to the handle. Such a coupling element may be configured to be coupled to, for example, a hook, wire, or similar pulling means, by means of which the forerunner may be advanced through the chamber of the profile element by means of an external power source or drive, mainly in the longitudinal direction, in order to facilitate retraction of the retaining lace. By providing such a coupling element, it will no longer be necessary to displace the forerunner manually and the presence of a handle will be obsolete.

[0021] According to further embodiments, the forerunner and/or the retaining lace are provided, near the narrow section, with an inward protrusion with a forward bevel. This bevel is configured to force the strip-shaped screen part deeper into the chamber.

[0022] Here, the expression "inward protrusion with a forward bevel" is understood to mean a body having a surface which is partly directed forwards in the longitudinal direction (i.e. the direction of retraction) and is partly directed inwards towards the second transverse direction (i.e. inwards into the chamber). The inward protrusion with forward bevel makes it possible to force the accommodated strip-shaped screen part further into the chamber as soon as the retaining lace and/or the forerunner is/are slid into the chamber in the longitudinal direction via the introduction opening of the profile element. In this way, the accommodated strip-shaped part of the screen is enlarged, and more play is created for this screen part to position itself inside the chamber with respect to the retaining lace (e.g. around the retaining lace). As a result, drawing of the retaining lace into the enclosed position and fixing of the accommodated strip-shaped screen part inside the chamber proceeds more smoothly. Preferably, the inwards protrusion with forward bevel has a smoothly curved profile in the forward and/or transverse directions), in order to reduce the frictional forces between the retaining lace and the strip-shaped screen part.

[0023] According to an embodiment, the retaining lace has a retaining lace width Ay I in a first transverse direction, and the longitudinal opening spans an opening width Ay2 in the first transverse direction. In this embodiment, the chamber is also delimited in the first transverse direction by two opposite inner wall parts which span a chamber width Ay3 in the first transverse direction. In this embodiment, the widths relate to one another as Ayl < Ayl < Ay3.

[0024] These widths for the retaining lace, the chamber and the longitudinal opening allow the retaining lace to remain freely movable in the longitudinal direction through the chamber of the profile element in the enclosed position, while preventing the retaining lace from exiting via the longitudinal opening of the chamber.

[0025] The chamber of the profile element may be formed substantially mirror- symmetrically with respect to a mirror plane through the longitudinal opening. The profile element may form, for example, an internal chamber with a mirror- symmetrical polygonal or semi-elliptical cross section. However, such mirror symmetry is not imperative.

[0026] According to a further embodiment, each inner wall part spans an inner surface, which is directed towards the chamber. In this embodiment, each inner wall part has an inner edge, which adjoins the longitudinal opening, and a set of transverse distances {ΔΓ} is defined between, on the one hand, a point on the inner edge associated with the opposite inner wall part and, on the other hand, a set of points on the inner surface. In this case, it holds true for each transverse distance ΔΓ in the set {ΔΓ} that ΔΓ < Ayl .

[0027] This limitation of the possible distances between the inner edge the opposite inner surface limits the freedom of rotation of the retaining lace about an axis in the longitudinal direction, and thus encloses the lace in such a manner that prevents the lace from being able to rotate so much that the lace can still slip out of the chamber via the longitudinal opening. Preferably, the inner surfaces are concave in character. Thus, the inner surfaces may have, for example, a curved or angular U-shape (in this case, the inner surfaces have a single curvature with a deepest surface part which is situated in/near a centre region of the concave inner surface, and the largest value in the set of transverse distances corresponds to this deepest surface part).

[0028] According to an embodiment, the profile element comprises two contact surfaces, which extend along the longitudinal opening in the longitudinal direction and face inwards into the chamber. In this embodiment, the retaining lace comprises two further contact surfaces which extend in the longitudinal direction in the enclosed position of the retaining lace and are directed towards and run virtually parallel to the contact surfaces of the profile element.

[0029] The retaining lace may be accommodated in the profile element in such a position that the further contact surfaces of the retaining lace directly face and run parallel with the two inward contact surfaces on both sides of the longitudinal opening. When the strip-shaped screen part is accommodated in the chamber, it can be clamped between the contact surfaces and further contact surfaces. The parallel contact surfaces result in an advantageous distribution of forces during transfer of the tensioning force from the screen to the profile element. The contact surfaces may be configured as parallel flat surfaces or have finite identical curvatures (i.e. curvatures not equal to zero).

[0030] According to alternative embodiments, at least one of the contact surfaces may be provided with an upright structure which extends in the longitudinal direction and is curved in the transverse direction. Such a structure provides a line contact between the retaining lace and the inner side of the inward contact surfaces, without sharp edges, as a result of which the pulling resistance can be reduced. One or more contact surfaces may be provided, for example, with a semi cylindrical structure which extends along the contact surface.

[0031] The longitudinal sides of the retaining lace may form line areas, which help to reduce the frictional resistance during sliding in or out of the lace.

[0032] The profile element may for example comprise two ridges, which are situated on two opposite sides of the longitudinal opening and face each other. In this case, the inward contact surfaces may be formed by inwardly facing surfaces of the ridges.

[0033] According to a preferred embodiment, the retaining lace is configured as a retaining strip. The retaining strip may be characterized by a strip length Δχΐ in the longitudinal direction X, a strip width Ay I in the first transverse direction Y, and a strip thickness Δζΐ in the second transverse direction Z, with Δχΐ » Ayl » Δζΐ . Such a retaining strip may be achieved, for example, by a substantially bar-shaped flat body with relatively homogenous elastic properties. Such a bar-shaped retaining strip may, for example, have a substantially rectangular cross section with sides Ayl and Δζΐ, or have a lens-shaped cross section with a width Ayl and a thickness Δζΐ, or have an ellipse-shaped cross section with axes Ayl and Δζΐ . Other elongate flattened shapes for a retaining strip wherein Δχΐ » Ayl » Δζΐ are also possible.

[0034] When fastening climate screens in a greenhouse or glasshouse, the retaining lace may, for example, have a width Ayl of between 5 millimetres and 25 millimetres, more specifically a width Ayl of between 10 millimetres and 20 millimetres, such as for example 15 millimetres. Preferably, the retaining lace has a thickness Δζΐ of 0.3 millimetres to 1 millimetres, more preferably between 0.5 millimetres and 0.6 millimetres. However, other dimensions of the strip are possible.

[0035] According to a second aspect, and in accordance with the above-described advantages and effects, the invention provides a screen assembly, comprising a fastening device with a profile element and a retaining lace according to the first aspect of the invention, and a screen with a strip-shaped screen part which can be accommodated in the chamber of the profile element, and wherein the retaining lace can be accommodated in the chamber in an enclosed position in order to clamp the strip-shaped screen part inside the chamber.

[0036] According to an embodiment, in the enclosed position, the retaining lace is situated between the longitudinal opening of the profile element on the one side, and the strip- shaped screen part on the other side.

[0037] If the screen is subjected to a tensioning force, this results in a pulling force on the strip-shaped screen part which is directed through the longitudinal opening and out of the chamber. If, in the enclosed position, the retaining lace is situated between the longitudinal opening and the strip-shaped screen part inside the chamber, then an increase of the pulling force on the screen part will also increase the clamping force on the retaining lace against the (inner side of the) longitudinal opening, which (temporarily) strengthens the fastening of the screen to the profile element.

[0038] According to a further embodiment, the retaining lace is provided with a lace surface which is directed along the second transverse direction into the chamber when the retaining lace is in the enclosed position, and with two longitudinal edges which form transverse ends of the retaining lace in the fu st transverse direction. In this embodiment, the strip-shaped screen part extends around the lace surface and both longitudinal edges of the retaining lace towards the longitudinal opening, where the strip-shaped screen part merges into one or more free screen parts.

[0039] The enclosure of the inward surface by the strip-shaped screen part via both longitudinal edges of the lace results in a clamping enclosure with a relatively symmetrical distribution of the tensioning/clamping forces across the lace, the screen and the profile element.

[0040] According to a further embodiment, the strip-shaped screen part comprises a guide strip for sliding the strip-shaped screen part and the guide strip via an introduction opening in the profile element into a retracted position inside the chamber of the profile element, while the screen continues to project outside via the longitudinal opening. In this embodiment of the assembly, the retaining lace in the enclosed position is situated between the longitudinal opening on the one side, and the strip-shaped screen part with the guide strip in the drawn-in position on the other side.

[0041] The use of a screen with a dedicated guide strip in combination with the abovementioned retaining lace and profile element may result in a more robust fastening, as a result of which greater tensile forces may be applied to the screen. In contrast with the independently movable retaining lace, the guide strip may be directly attached to the screen in advance, for example by means of stitching, gluing, fusing, stapling and the like. The guide strip forms a relatively flat flexible hardened section which is attached to the screen along the strip-shaped screen part, in order to facilitate insertion of the screen via the introduction opening of the profile element and guiding of the screen along the profile element.

[0042] Typically, the guide strip has a significantly greater flexural stiffness than the screen, but this flexural stiffness of the guide strip presents no impediment for rolling up of the screen about an axis in the first transverse direction, in order to form a screen roll. The guide strip may have the same flexibility properties as said properties of the retaining lace. However, the guide strip does not have to be "supportive", i.e. of such a strength and dimension to be able to keep the screen in the tensioned position by itself.

[0043] Preferably, the screen is configured as a translucent film/foil of a relatively uniform transparent material of relatively homogenous thickness. Such a film/foil screen may be used, for example, as an inner cover layer underneath a first cover layer of translucent rigid sheet material, in order to form a cavity with a controllable air layer in between.

[0044] The first cover layer of translucent rigid sheet material may be, for example, a panel of glass or of hard translucent plastic, which forms part of Lhe roof structure of a greenhouse or glasshouse. Fastening the guide strip to the film/foil layer may be effected, for example, by means of stitching, gluing, or fusing. In practice, the resulting connection between film/foil screen and guide strip can be relatively weak, so that the risk of damage to the film/foil screen during initial tensioning and subsequent use is relatively great. According to this embodiment of the invention, the film/foil screen can be temporarily pulled into the profile element by means of the guide strip, while clamping and fixing the film/foil screen by means of the retaining lace and subsequent placement of the profile element and tensioning the screen may be carried out later at any desired moment.

[0045] According to a third aspect, the invention provides a greenhouse or glasshouse, comprising: a supporting structure, and a screen assembly with fastening devices according to the first aspect of the invention, and a screen which is suspended on opposite longitudinal edges from the supporting structure by means of the fastening devices.

[0046] According to an embodiment, the greenhouse or the glasshouse comprises a roof which is supported by the supporting structure. This roof comprises at least one gutter, a roof-ridge which is situated at a distance from the gutter, bars which extend between the gutter and the roof-ridge, at least one panel which is accommodated between the bars, the roof-ridge and the gutter, and the screen, which is attached at or near the gutter and the roof-ridge by means of the fastening devices and which extends at a distance from and substantially parallel to the panel, with a cavity being formed between the screen and the panel.

[0047] Preferably, on at least one strip-shaped screen part, the screen is provided with a guide strip, which is configured for sliding in the strip-shaped screen part via an introduction opening of the profile element. Such a screen with guide strip may be formed, for example, from a translucent film/foil layer of relatively uniform thickness.

[0048] According to an alternative embodiment, the supporting structure of the greenhouse or the glasshouse comprises: posts, girders which are supported by the posts and are situated parallel to each other, at least one fastening device which is configured as a screen frame to which the screen is attached and which can be moved to and fro between an open position and a closed position, and a drive for moving the screen frame to and fro.

[0049J If desired, the supporting structure may comprise a wire frame comprising mutually parallel wires, which are attached substantially horizontally between the girders. In this case, the screen frame may be arranged so as to be movable to and fro between the open position and the closed position along the wires.

[0050] According to yet another embodiment, the supporting structure of the greenhouse or the glasshouse comprises: posts, girders or gutters that are supported by the posts and are situated parallel to each other, and at least one fastening device that is attached along a girder or gutter. In this embodiment, the screen is attached to the supporting structure by means of the fastening device and spans a flexible roof or flexible wall of the greenhouse or the glasshouse. Preferably, the flexible roof and/or the flexible wall in this case forms an outer side of the greenhouse or the glasshouse.

[0051] The greenhouse or the glasshouse may comprise a second screen, which is attached to the supporting structure in a similar way by means of the fastening device to span a flexible roof or flexible wall of the greenhouse or the glasshouse. The screen and the second screen may in this case be situated substantially next to each other, with a cavity being formed between the screen and the second screen.

[0052] The screen may be attached to the fastening device indirectly along the corresponding girder or gutter, or may be attached directly to the girder or gutter.

Irrespective of the way of fastening, several girders or gutters may be provided with such fastening devices, so that the screen can be fixed to the supporting structure along more than one strip-shaped screen part. Thus, the screen and the second screen (viewed in a width direction) may be fixed along two fastening devices which run virtually parallel to two adjacent gutters, and the cavity may be formed (viewed in a height direction) in between the screen and the second screen.

[0053] According to a fourth aspect, the invention provides a method for fastening a screen to a structure. This method comprises:

providing a fastening device according to the first aspect of the invention;

- positioning the screen with a strip-shaped part in or near the chamber of the profile element; drawing the retaining lace into the chamber via an introduction opening of the profile element until it reaches an enclosed position, in order to clamp the strip-shaped screen part in the chamber.

[0054] Before placement of the retaining lace, the screen may already be positioned in the profile element in such a way that the strip-shaped screen part is enclosed by the chamber ("in the chamber"), but has possibly not yet been fixed therein. Alternatively, the screen may only be positioned against the profile element ("near the chamber") before placement of the retaining lace, without the strip-shaped screen part being enclosed by the chamber.

[0055] According to an embodiment, the strip-shaped screen part comprises a guide strip for sliding the screen into the profile element. In this embodiment, the positioning of the screen also comprises sliding the guide strip with the strip-shaped screen part into the chamber via the introduction opening of the profile element towards a drawn-in position inside the chamber. In addition, the sliding in of the retaining lace also comprises placing the retaining lace inside the chamber abutting the guide strip, preferably in such a way that the retaining lace is, in the enclosed position, situated between, on the one hand, the longitudinal opening of the profile element and, on the other hand, the strip-shaped screen part with the guide strip in the drawn-in position.

[0056] According to a further embodiment, the method may, in an initial phase, comprise the following:

providing the screen with the guide strip along the strip-shaped screen part in the form of a roll, a roll axis of which is directed at right angles to a longitudinal direction of the guide strip, and in which the guide strip is rolled up with a width direction which is oriented parallel to the screen;

- placing the roll near the introduction opening of the profile element;

transferring an unrolled end of the roll with the strip-shaped screen part and the guide strip near the introduction opening of the profile element, and

unrolling the roll and simultaneously sliding in the strip-shaped screen part and the guide strip through the chamber of the profile element.

[0057] According to yet another embodiment, the method may comprise:

rotating the guide strip locally about the length direction, out of the plane of the screen during unrolling of the roll, in such a way that the guide strip is accommodated at a finite angle β with the screen in the chamber of the profile element, with 0° < β < 180°; subsequently introducing the retaining lace into the chamber of the profile element.

[0058] It will be clear that the various aspects mentioned in the present patent application can be combined and may each be considered individually for a divisional patent application.

BRIEF DESCRIPTION OF THE FIGURES

[0059] Next, exemplary embodiments of the invention will be described solely by way of example by means of the attached diagrammatic drawings, in which corresponding components are denoted by corresponding reference numerals.

[0060] Figures la and lb show a roof structure of a greenhouse according to an embodiment;

[0061] Figures 2a and 2b show parts of a screen assembly according to an

embodiment;

[0062] Figure 3 a shows a diagrammatic top view of a screen assembly according to an embodiment;

[0063] Figure 3 b shows a diagrammatic side view of the screen assembly from Figure 3a;

[0064] Figures 4a-4c show diagrammatic cross sections of the screen assembly from Figures 3a-3b;

[0065] Figure 5 shows a cross section of the profile element from Figures 3a-3b;

[0066] Figures 6a and 6b show diagrammatic cross sections of a screen assembly according to an alternative embodiment;

[0067] Figure 7 shows a diagrammatic cross section of a screen assembly according to yet another embodiment, and

[0068] Figure 8 shows a forerunner in an alternative embodiment of a fastening device.

[0069] The drawings are only intended to serve for illustrative purposes and not in order to limit the scope of protection which is defined by the claims. DESCRIPTION OF EMBODIMENTS

[0070] Figures la and lb show an embodiment of a greenhouse 10. The greenhouse 10 comprises a supporting structure 12, 14, which is composed of several elements, and a roof construction 20 which is supported by the supporting structure 12, 14 and is arranged as a series of connected slanting roof sections.

[0071] The supporting structure 12, 14 comprises posts 12 (supporting columns), and girders 14 (trusses) which are supported by the posts 12 and are situated parallel to each other. The roof construction 20 comprises gutters 16, roof-ridges 22, bars 18 and panels 26. The roof-ridges 22 are at a distance from the gutters 16. The bars 18 run obliquely upwards and extend between a specific gutter 16 and roof-ridge 22. The roof-ridges 22 are supported on the bars 18. The panels 26 are accommodated between the bars 18, the roof- ridge 22, and the gutter 16. In this example, the panels 26 comprise glass panels. Every slanting roof part comprises a sequence of panels 26 and bars 18 which are at virtually the same gradient.

[0072] The greenhouse 10 also comprises a number of climate screens 60, wherein each screen 60 corresponds to a specific roof part. Figure la shows at least one screen 60. Such a climate screen 60 is suspended from the supporting structure 12, 14 along opposite edges of a roof part by means of a first fastening device 30i and a second fastening device 30j. The first fastening device 30i is attached to (or forms part of) the gutter 16. The second fastening device 30j is attached to (or forms part of) the roof-ridge 22. Where a distinction is less relevant, the fastening devices are generally denoted by reference numeral 30. The fastening devices 30 each comprise an elongate profile element 40 which is provided either along the gutter 16 or along the roof-ridge 22.

[0073] The screen 60 may consist of, for example, a transparent film/foil layer of relatively uniform thickness. Each screen 60 extends at a distance from and substantially parallel to the panels 26 of an associated roof part. Thus, a cavity 28 is formed between the screen 60 and the panels 26 of this roof part. Such a cavity 28 can quickly be constructed by means of the transparent film/foil screen 60. The layer of air in this cavity 28 can be controlled thermally and/or hydrologically, so that the cavity 28 can be used very advantageously for the purpose of regulating the climate inside the greenhouse 10.

[0074] Near the edges, the film/foil screen 60 is provided with guide strips 74 which are configured for sliding in the screen 60 via an introduction opening of the profile element during installation. Fastening the guide strip 74 to the film/foil screen 60 may be effected, for example, by means of stitching, glueing or fusing. In practice, the resulting connection between film/foil screen 60 and guide strip 74 can be relatively weak, so that the risk of damage to the film/foil during initial tensioning and subsequent use may be relatively great.

[0075] Therefore, the screen 60 is fixed along the edges in the elongate profile elements 40 by means of retaining laces 80 to improve the clamping action. After the improvement of clamping and fixing of the film/foil screen 60 by means of the retaining laces 80, the screen 60 can be subjected to tension.

[0076] By means of Figures 2a-8, details and variant embodiments of the fastening devices 30 will be explained further.

[0077] Figures 2a and 2b show parts of a screen assembly 32 according to an exemplary embodiment. The illustrated screen assembly 32 comprises a fastening device 30 and a screen 60.

[0078] The screen 60 forms a sheet-shaped element which can fulfil one or more climate-regulating functions, such as sunblind, darkening, moisture regulation, flow barrier and/or thermal insulation. The screen 60 may be, for example, the film/foil screen from Figures la and lb, but may also be embodied differently, such as a cloth (e.g. of the woven or knitted type), a mat or a film/foil web screen.

[0079] The fastening device 30 is configured for fastening a screen 60 along a strip- shaped screen part 66 to a structure, such as to the supporting structure 12, 14 of the greenhouse 10 from Figures la and lb. The fastening device 30 is formed by a profile element 40 and a retaining lace 80.

[0080] In this example, the profile element 40 is formed as an elongate body which extends in a longitudinal direction X. The profile element 40 forms a chamber 42, a longitudinal opening 44, and at least one introduction opening 46. The chamber 42 extends in the longitudinal direction X through the profile element 40 and forms an elongate space in which a part of the screen 60 and the retaining lace 80 can be accommodated. The longitudinal opening 44 extends in the longitudinal direction X along a side of the profile element 40 and forms a passage between the chamber 42 and an outer side of the profile element 40. The introduction opening 46 is directly connected to the chamber 42. In this example, the introduction opening 46 forms a head-end opening 46 provided at a longitudinal end of the profile element 40.

[0081] The retaining strip 80 (see Figure 2b) is configured in such a way that it can be accommodated in the chamber 44 of the profile element 40 along the longitudinal direction X. Preferably, the retaining lace 80 is sufficiently flexible so that the longitudinal ends 82 can be bent towards each other, so that the retaining lace 80 can be rolled up around an axis in a transverse direction. This facilitates transportation and storage of the retaining lace 80. In this example, the retaining lace 80 is configured as an elongate, slightly flexible strip with a substantially flat bar-shaped body. This bar-shaped body has a strip length Δχΐ in the longitudinal direction X, which is significantly greater than a strip width Ayl in the first transverse direction Y, which in turn is significantly greater than a strip thickness Δζΐ in the second transverse direction Z. In this example, the strip width Ayl is approximately 15 millimetres and the strip thickness Δζΐ approximately 0.5 millimetres. Other dimensions are possible, depending on the requirements regarding weight and further stress on the screen 60, and/or the available space and fastening options for the profile element 40.

[0082] Figure 2a shows that a strip-shaped part 66 of the screen 60 can be positioned along the longitudinal opening 44 of the profile element 40. If desired, the strip-shaped part 66 of the screen 60 may at least partly be pushed into the chamber 42 of the profile element 40, but this is not imperative.

[0083] Figure 2b shows that the retaining lace 80 can then be retracted into the chamber 42 via the introduction opening 46 of the profile element by means of a movement in the longitudinal direction X. The retaining lace 80 is retractable,

independently from the screen 60 and through the introduction opening 46 of the profile element 40, from a free position in which the retaining lace 80 is situated completely outside the chamber 42, to an enclosed position in which the retaining lace 80 is accommodated in the chamber 42. In the enclosed position, the retaining lace 80 clamps the strip-shaped screen part 66 in the chamber 42, so that the screen 60 is fixed with respect to the profile element 40.

[0084] In the enclosed position inside the chamber 42, the retaining lace 80 has limited freedom of movement, at least in the transverse directions Y, Z at right angles to the longitudinal direction X. If desired, the retaining lace 80 in the enclosed position is able to be rotated or moved in translation in the transverse directions X, Z along relatively small distances and/or angles, provided this does not result in the retaining lace 80 exiting the longitudinal opening 44 of the chamber 42.

[0085] The retaining lace 80 and the screen 60 do not have any direct mutual attachment (i.e. no mutual attachment if retaining lace 80 and screen 60 are situated entirely outside the chamber 42), such as stitching, glue, fusing or staples. [0086] Figure 2b shows that the longitudinal opening 44 of the profile element 40 is delimited by ridges 48a, 48b on both sides viewed in the first transverse direction Y. The longitudinal opening 44 spans an opening width between these ridges 48a, 48b (see Figure 4a).

[0087] The retaining lace has longitudinal ends 82 in the longitudinal direction X. Near a first longitudinal end 82a, the retaining lace 80 has a handle 94 and a narrow section 92 in the first transverse direction Y. The narrow section 92 allows the retaining lace 80 in the enclosed position to project partly outside the chamber 42 of the profile element 40 through the longitudinal opening 44 at the location of the narrow section 92.

[0088] At the location of the narrow section 92, the retaining lace 80 is provided with an inward protrusion 96 in order to force the strip- shaped screen part 66 deeper into the chamber 42, where the retaining lace 80 is pulled through the chamber 42 across this screen part 66.

[0089] Figures 3a and 3b show diagrammatic top and side views of the screen assembly 32 from Figure 2b. As is illustrated in Figures 2a and 2b, the screen 60 only has to be positioned against the longitudinal opening 44 of the profile element 40, without the strip-shaped screen part being enclosed by the chamber 42, before the retaining lace 80 is retracted.

[0090] Figure 3 b shows that the retaining lace 80 has a forward bevel 98 at the inward protrusion 96. The inward protrusion 96 with forward bevel 98 forms a surface which is directed partly forwards towards the longitudinal direction X (i.e. in the retracting direction) and directed partly inwards along the second transverse direction Z (i.e. inwards along -Z into the chamber 42). The inward protrusion 96 with the forward bevel 98 ensures that a part of the pulling force, which is exerted while pulling the retaining lace 80 into the chamber 42, is transformed into a force distribution for forcing/pushing the strip- shaped screen part 66 into the chamber 42. By the pushing in, the accommodated strip- shaped part 66 of the screen 60 is enlarges, which provides more play for this screen part 66 to be able to fold itself around the retaining lace 80 inside the chamber 42. Preferably, the inward protrusion 96 with forward bevel 98 has a smoothly curved profile in the forward and/or transverse direction(s), in order to reduce the frictional forces between the retaining lace 80 and the strip-shaped screen part 66. [0091] Figures 4a-4c show diagrammatic cross sections of the screen assembly 32 from Figures 3a-3b. As has already been mentioned, the retaining lace 80 in these exemplary embodiments is strip-shaped.

[0092] Figure 4a shows that the profile element 40 is formed mirror- symmetrically with respect to a mirror plane through the longitudinal opening 44. The retaining lace 80 extends in the first transverse direction Y with a lace width Ayl. The longitudinal opening 44 of the profile element 40 spans an opening width Ay2 in the first transverse direction Y. Furthermore, the chamber 42 of the profile element 40 in the first transverse direction Y is delimited by two opposite inner wall parts 54a, 54b which span a chamber width Ay3 in the first transverse direction Y. In this example, the relationship between said widths is

Ay2 < Ayl < Ay3. This width relationship makes it possible for the retaining lace 80 in the enclosed position to remain freely movable through the chamber 42 of the profile element 40 in the longitudinal direction X, while preventing the retaining lace 80 from exiting via the longitudinal opening 44 of the chamber 42.

[0093] Figure 4a also shows that the ridges 48a, 48b around the longitudinal opening 44 of the profile element 40 have two contact surfaces 52a, 52b. These contact surfaces 52a, 52b extend along the longitudinal opening 44 and are directed inwards into the chamber 42. The retaining lace 80 has two further contact surfaces 88a, 88b which, in the enclosed position of the retaining lace 80, extend in the longitudinal direction X and are directed towards and run virtually parallel with the contact surfaces 52a, 52b of the profile element 40. The strip-shaped screen part 66 inside the chamber 42 can be clamped between these contact surfaces 52a, 52b, 88a, 88b, which results in an advantageous distribution of forces if a tensioning force is transferred to the profile element 40 via the screen 60.

[0094] Figure 4b shows, by means of a cross section, how the retaining lace 80 in the enclosed position is situated between the longitudinal opening 44 of the profile element 40 on the one side, and the strip-shaped screen part 66 on the other side. Due to this positioning with respect to each other, an increase in the pulling force on the screen 60 will also increase the clamping action by the retaining lace 80 against the inner sides of the longitudinal opening 44 of the profile element 40, which (temporarily) improves the attachment of the screen 60 to the profile element 40.

[0095] The retaining lace 80 has a lace surface 86 which is directed into the chamber 42 along the vertical direction Z, and two longitudinal edges 84a, 84b which form transverse ends of the retaining lace in the first transverse direction Y. In the enclosed position, the strip-shaped part 66 of the screen 60 extends around the lace surface 86 and along both longitudinal edges 84a, 84b of the retaining lace 80 towards the longitudinal opening 44, where the strip-shaped screen part 66 merges into one or more free screen parts 68a, 68b. The fact that the strip-shaped part 66 encloses the screen 60 in this way results in an advantageous symmetrical distribution of the tensile forces across the retaining lace 80, the screen 60, and the profile element 40.

[0096] Fi gure 4b also shows how the narrow section 92 of the retaining lace 80 projects out of the chamber 42 of; the profile element 40 through the longitudinal opening 44 in such a way that the handle 94 of the retaining lace 80 is readily accessible from outside the profile element 40. To this end, the narrow section 92 has a width Ay4 in the first transverse direction Y which is smaller than the width Ay2 of the longitudinal opening 44, so that the handle 94 can project out of the chamber 42 and with a component along the second transverse direction Z, while the largest part of the retaining lace 80 remains inside the chamber 42 in the enclosed position.

[0097] Figure 4c shows by means of a cross section how the protrusion 96 of the lace element 80 can facilitate forcing the strip-shaped part 66 of the screen 60 deeper into the chamber 42.

[0098] Figure 5, by means of a cross section, shows some dimensional properties of the profile element 40 according to this exemplary embodiment. The two opposite inner wall parts 54a, 54b of the profile element 40 each span an inner surface 56a, 56b which is directed towards the chamber 42. Each inner wall part 54a, 54b is delimited by an inner edge 50a, 50b, which is situated at the end of the corresponding ridge 48a, 48b near the longitudinal opening 44.

[0099] In this exemplary embodiment, the inner surfaces 56a, 56b are concave and have an angular asymmetrical U shape. Between, on the one hand, a point on the first inner edge 50a associated with the first inner wall part 54a and, on the other hand, a set of points on the second inner surface 56b of the second inner wall part 54b, a set of transverse distances {ΔΓ} is defined, in this case as a function of a rotation angle a about a longitudinal axis through the point on the inner edge 50a. For each transverse distance Ar in the set {Ar}, it holds true that ΔΓ is smaller than the lace width Ay 1. In this example, a similar requirement also holds true for, on the one hand, a point on the second inner edge 50b associated with the second inner wall part 54b and, on the other hand, a set of points on the first inner surface 56a of the first inner wall part 54a. This requirement limits the rotational freedom of the retaining lace 80 about an axis in the longitudinal direction X, and thus yields an enclosure that prevents the retaining lace 80 from rotating so far that it can slip out of the chamber 42 via the longitudinal opening 44.

[00100] Figures 6a and 6b show diagrammatic cross sections of a screen assembly according to an alternative embodiment, in which the screen is already provided with a guide strip 174. The guide strip 174 is attached directly to the screen 160, for example by means of stitching, gluing, fusing or stapling. The guide strip 174 forms a relatively flat flexible hardened section, which is attached to the screen 160 at the location of the strip- shaped part 166 of the screen 160, to facilitate insertion of the screen 160 via the introduction opening of the profile element 140 and guiding of the screen 160 along the profile element 140.

[00101] Initially, the strip-shaped screen part 166 with the guide strip 174 may be retracted into the chamber 142 of the profile element 140 via the introduction opening. In this case, the free screen parts 168a, 168b of the screen 160 will project out of the longitudinal opening 144 while the screen 160 and the guide strip 174 are retracted. The screen 160 with the guide strip 174 along the strip- shaped screen part 166 may have been supplied beforehand in the shape of a roll, in which the guide strip 174 has been rolled up with a width direction oriented parallel to the screen 160. An unrolled end of the roll with the strip-shaped screen part 166 and the guide strip 174 may be placed near the introduction opening of the profile element 140 and be pulled into the chamber of the profile element 140.

[00102] After the screen 160 has been positioned, the retaining lace 180 can be retracted, similar to the procedure illustrated in Figure 2b. In the enclosed position, the retaining lace 180 will be situated between the longitudinal opening 144 on the one side, and the strip-shaped screen part 166 with the guide strip 174 on the other side. Advantages of this embodiment, which uses both a guide strip 174 and a retaining lace 180, have already been discussed above (inter alia with reference to Figures la and lb).

[00103] Figure 7 shows, by means of a cross section, that the fastening device with the profile element 240 and the retaining lace 280 according to other embodiments can also be used to fix a plurality of screens. Figure 7 shows an assembly 232 comprising two screens 260, 261 which is clamped simultaneously by the fastening device. [00104] Such a double/multiple clamping of screens may, for example, be applied quickly and efficiently to construct a greenhouse in which the screens 260, 261 span a flexible roof part and/or wall part of the greenhouse. Such a greenhouse may be formed by, inter alia, a supporting structure with posts and girders (for example gutters) which run parallel to each other and are supported by the posts, and a number of fastening devices which are fastened along girders, in such a way that the screens 260, 261 can be fixed along these in a clamping manner. In this case, the two screens 260, 261 may be situated alongside and partly against each other, in order to define the main contours of the roof part and/or wall part. If desired, a cavity may be formed between the two screens 260, 261, at the location of the free screen parts 268a, 269a or 268b, 269b where the screens 260, 261 are not clamped by the fastening devices. Such a cavity may, for example, be formed by blowing air between the free screen parts 268a, 269a or 268b, 269b of the screens 260, 261 using a pump device.

[00105] Figure 8 illustrates an alternative embodiment of the fastening device 330 which has similarities with the fastening device 30 from Figure 3b.

[00106] Here, the fastening device 330 comprises a forerunner element 100. This forerunner 100 is formed by a sliding body 102 with a handle 104 and a fastening element 103. The sliding body 102 has a shape which corresponds to the inner shape of the chamber 342 of the profile element 340, and can be accommodated therein. The fastening element 103 is provided at an end of the sliding body 102, and is configured to fasten the forerunner 100 to a longitudinal end 382a of the retaining lace 380. Here, the handle 104 forms a part of the sliding body 102 and has a width which allows this handle 104 to project outside through the longitudinal opening 344 of the chamber. To this end, the handle 104 has a width Ay4 in the first transverse direction Y, which is smaller than the width Ay2 of the longitudinal opening 344 in the profile element 340, so that the handle 104 can project outside the chamber 342 along the second transverse direction Z while the retaining lace 380 remains in the enclosed position inside the chamber 342.

[00107] The forerunner 100 has an inward protrusion 106 with a forward bevel 108, which is configured to force the strip-shaped part 366 of the screen 360 deeper into the chamber 342. The forerunner 100 is furthermore provided with a widened section 105 which, viewed in the longitudinal direction X, is situated behind the forward bevel 108 and the protrusion 106. The widened section 105 serves as a transition form that essentially matches with the lace width of the (coupled) retaining lace 380. The widened section 105 helps to deform the screen part 366 - which is enlarged in the second transverse direction Z by means of the inward protrusion 106 - along the first transverse direction Y, in order thus to facilitate the enclosure of the screen part 366 in the chamber 340 during retraction of the retaining lace 380.

[00108] The forerunner 100 may be placed in the profile element 340 independently from the retaining lace 380 and facilitates sliding of the retaining lace 380 into the chamber from the free position via the introduction opening 346 into the enclosed position. Alternatively or in addition to the handle 104, the forerunner may, in other embodiments, be provided with a further coupling element (such as a pulling eye), which makes it possible to couple the forerunner to an external power source (for example via a hook and/or cable), in order to be able to move the forerunner in the longitudinal direction through the chamber of the profile element in a different way than by manual operation.

[00109] It will be clear that the above-described embodiments are only described by way of example and not in any limiting sense, and that various changes and modifications are possible without departing from the scope of the invention and that the scope is only determined by the attached claims.

[001 10] The reference numerals in the claims only serve as an illustration and should not be seen as a limitation to the interpretation of the claims. For the sake of brevity, similar reference numerals which correspond to similar elements of embodiments described in the claims are only denoted by their base numerals (i.e. without the hundreds) in those cases where there are similarities with several embodiments. This does not suggest that these claim elements only refer to elements in the description which correspond to a base numeral. Thus, for example, the reference numeral (30) in the claims should be read as (30; 130; 230; 330) in those cases where the similarity applies. The applicability of several similar reference numerals in the claims may be determined by a comparison with the figures and the description. In cases where a similarity refers to a specific embodiment, specific reference numerals using hundreds are used in the claims.

[00111] In the above-described exemplary embodiments, the retaining lace was strip- shaped. In alternative embodiments, the retaining lace may equally well be configured as a flexible, but strong, hose, hollow tube, rope or other kind of elongate body.

[00112] In addition, the profile elements in the above-described exemplary

embodiments were substantially linear in shape. In alternative embodiments, it is possible for the profile element to have a certain curvature in the second transverse direction Z as a function of the longitudinal direction X, provided the curvature is sufficiently gradual (i.e. smooth) to allow retraction of the retaining strip and enclosure of the screen. In these cases, the longitudinal direction may be considered more broadly as "retraction direction", and the orientations of the first and second transverse directions Y, Z will vary locally according to the position along the retraction direction X.

[00113] According to alternative embodiments, the supporting structure of the greenhouse or the glasshouse may be provided with posts and with mutually parallel girders which are supported by the posts, with at least one fastening device which is configured as a screen frame to which the screen is attached, and which is arranged so as to be movable to and fro between an open position and a closed position, and with a drive for moving the screen frame to and fro.

[001 14] The supporting structure may also comprise a wire frame with mutually parallel wires which are pulled taut substantially horizontally between the girders. The screen frame may in this case be arranged so as to be movable to and fro between the open position and the closed position along the wires.

[00115] According to further alternatives, the supporting structure of the greenhouse or the glasshouse may be provided with posts and with girders and/or gutters which are supported by the posts, and are situated mutually parallel; with a fastening device which is attached along a girder or gutter; in which the screen is attached to the supporting structure by means of the fastening device and spans a flexible roof or flexible wall of the greenhouse or the glasshouse. In this case, the flexible roof and/or the flexible wall forms an outer side of the greenhouse or the glasshouse.

[00116] Such a greenhouse or glasshouse may comprise a second screen which is attached to the supporting structure in a similar way by means of the fastening device to spans a flexible roof or flexible wall of the greenhouse or the glasshouse. The screen and the second screen may in this case be situated substantially next to each other, with a cavity being formed between the screen and the second screen. LIST OF REFERENCE NUMERALS

Similar reference numerals which are used in the description to denote similar elements (but only differ in respect of the hundreds) have been omitted from the following list, but are considered to be implicitly included.

10 greenhouse (or glasshouse)

12 column

14 truss

16 gutter

18 bar

20 roof

22 roof-ridge

24 supporting beam

26 panel (e.g. glass panel)

28 cavity

30 fastening device

32 screen assembly (screen installation)

34 fixed screen profile

40 profile element

42 chamber

44 longitudinal opening chamber

46 head-end chamber opening

48a-b ridge

50a-b inner edge

52a-b contact surface

54a-b inner wall part

56a-b inner surface (for example having a concave rectangular U shape)

60 screen (e.g. film/foil)

61 further screen (e.g. film/foil)

62 longitudinal edge

64 transverse edge

66 strip-shaped screen part

67 further strip-shaped screen part

68a-b free screen part 69a-b further free screen part

70 film/foil web

72 weaving yarn

74 guide strip

76 fastening (e.g. stitched border)

78 screen roll

80 retaining lace

82a-b longitudinal end

84a-b lace edge

86 surface

88a-b further contact surface

92 narrow section

94 handle

96 inward protrusion

98 forward bevel

100 forerunner

102 sliding body

103 fastening element

104 handle

105 widened section

106 inward protrusion

108 forward bevel

X longitudinal direction

Y first transverse direction

z second transverse direction

ΔΓ distance between profile edge and inner surface

{ΔΓ} set of distances

Δχΐ lace length

Ayl lace width

Ay2 opening width

Ay3 chamber width

Ay4 lace width at narrow section

Ay5 guide lace width Δζΐ lace thickness