WO2006051360A2

WO2006051360A2 - Screening arrangement and cloth therefor

Info

Publication number: WO2006051360A2
Application number: PCT/IB2005/002810
Authority: WO
Inventors: Ruud Vlottes; Mar Van Staalduinen
Original assignee: Leen Huisman Bv
Priority date: 2004-09-22
Filing date: 2005-09-22
Publication date: 2006-05-18
Also published as: NL1027091C2; WO2006051360A3

Abstract

Screening arrangement for the screening of crops in a greenhouse (1), which arrangement comprises at least one screening part (4, 5, 7) that can be brought in a folded and an unfolded condition by means of an automatic control unit of the arrangement, which control unit comprises an electronic control unit, a control element adhering to a screening part such as a back and forth going cable, and an actuation unit for said control element, characterized in that the screening part comprises at least two cloths incorporated in the arrangement mutually above one another, and which cloths are each provided with several, transversely to the direction of movement of the control element extending panels, such that a panel, in the direction of shifting of the control element is each time alternated with a panel of a distinguishing transmissibility for light.

Description

SCREENINGARRANGEMENTANDCLOTHTHEREFOR

The present invention relates to a screening arrangement as is provided in the characterising portion of the following claim 1.

Greenhouses and screening arrangements therefor are generally known and are being applied commercially for several decades on a large scale. Given the level of investments involved with this, it is of crucial importance that the crops grown therein perform optimally. To this end thus, several advanced techniques and design rules have been developed, both with respect to the green houses and with respects to the crops grown therein. Many of these relate to optimising the amount and manner of incidence of light, and are on the one hand directed to the design of the greenhouse, and on the other hand directed to screening arrangements to be incorporated therein. Examples of the known greenhouse as well as of the known screening arrangements therein, are amongs others given by NL-A-1003741 and NL-A-1022083, both in the name of Applicant. Screening cloth for such arrangements are in general know, amongst others, in the brand name Ludvig Svensson.

The applied screening arrangements are amongst others intended for regulating the amount and duration of light incidence. To this end they may be brought from a folded condition to an unfolded condition. They may be equipped with various sorts of cloth, amongst which totally darkening, and shadowing cloth. The unfolding of a screening arrangement most often occurs in parts of a greenhouse, in particular between two frame girders of a greenhouse. This is performed automatically by means of a central motor, a push and/or pull unit, .which often comprises a cable and stretches along and seizes all of the screening parts, as well as a control unit of the whole. The seizure of a screening part occurs via a grabber part in the form of a stiff profile connected to the end of a cloth of a screening part.

A disadvantage of the known arrangement is that the control and fine tuning of the arrangement, in particular at crops that are to be screened against excessive incidence of light, provides insufficient possibilities for optimum crop growing. For such kind of sensitive and often expensive crops, it appears that the known screening arrangements opens and closes slowly, and that the shadow index of the arrangement, as a consequence of the once chosen and installed screening cloth, can not be influenced other than by opening or closing. It is at this point remarked that e.g. half closed cloths would lead to an uneven exposure to light and thus to uneven development of the crop, which is highly undesired. The pre-mentioned disadvantage goes along with the circumstance that the controller of such screens needs to have build in significant delay and stay periods for attaining a reasonably tranquil operation of the arrangement, and to prevent wear thereof.

The present invention for that reason has the object of rendering a principally improved screening arrangement in the mentioned respects.

In accordance with the invention such is achieved when the features as represented in the characterising portion of claim 1 are applied. A such principally renewed screening arrangement comprises at least two screening layers, incorporated in the arrangement at some distance, which are each-provided with parts of differing transmissibility for light. The total light incidence in a greenhouse is regulated by mutual movement of the screens. At doing so, the parts differing in transmission of light become or do not become situated above one another, or become situated only partially above one another. Preferably these parts are shaped by transversely to the opening and closing direction oriented panels of differing light transmissibility. The panels of a screen show a mutually differing transmissibility of light. Incidentally, the transmissibility between two screening layers may also differ. The panels are preferably incorporated in a regular pattern, so that at displacement of one of the two screening layers a predictable pattern of light, or alternatively an amount of diffusiveness of scattered light occurs within the greenhouse. Preferably in each of the both screening layers a panel of limited light transmissibility is mixed with a light- blocking panel, i.e. of zero transmissibility. By applying, in accordance with the invention, at least two screening layers with panels of differing transmissibility for light it becomes possible to influence the amount of incidence of light in a greenhouse in dependence of the mutual position of the screening layers of the arrangement. The width of the panels is many times less than the length of a screen, i.e. in the opening and closing direction, so that with a relatively small stroke of displacement in the opening and closing direction of one or otherwise both the two screening layers, in a relatively simple and moreover swift manner, an adaptation of the transmissibility of light of the screening arrangement can be attained, while above all, at least within a large range of percentages of shadowing, an almost stepless variation can be attained.

With a view to realisation of the new screening arrangement as set out in the preceding, the invention further encompasses a new type of screening cloth, as is represented in independent claim 24. The screening cloth according to the invention is provided with panels of material of a uniform amount of transmissibility of light, which transmissibility differs per panel. The panels are incorporated in a regular pattern in which the panels of a certain transmissibility for light, which can be zero, repeat in a fixed manner. In this manner a screening cloth has at least two differing panels, which each have a differing level of transmissibility of light. The panels are embodied in a fixed width in the range of 5 to 100 cm. Preferably the panels of differing transmissibility for light are embodied in a corresponding width.

In a further embodiment of the invention, the greenhouse, or alternatively the screening arrangement are made with a third screen, dedicated to filtering out unwanted parts of the spectrum of sun light, alternatively posed for the promotion of other parts thereof. This screen may be embodied either with a single or with a double or multiple layer. In the latter cases the spectrum may be adapted by mutual shifting. In each case the amount of illumination, i.e. the amount of shadowing may be adapted to measured values of the sun light, i.e. reduced, or the duration of illumination may be adapted, so as to allow the desired part of the spectrum in an extended amount to the crop in this way.

The invention will now by way of example be elucidated closer along a drawing in which: Figure 1 is a sketch of the principle of a greenhouse according to the invention;

Figure 2 is an elaboration of the invention, in which the screening arrangement is formed by two screens that are included above one another;

Figure 3 is an elaboration of the invention in which the screen is formed by three screen included above one another; Figure 4 illustrates an optional design of a screen according to the invention.

In the figures, corresponding constructive parts are referred to by equal reference signs.

Figure 1 shows a principle of the present invention along a greenhouse 1 of an indifferent, generally accepted type of greenhouse, in this case a so-called Venlo- greenhouse. The greenhouse is provided with a roof part 2, and a growing space 3, These are separated by a separation 4, in the form of a light transmissible, air closing material such as glass or a synthetic foil. The greenhouse 1 is further provided with an in itself generally known screening arrangement 5. This one is, together with the separation 4 included in a thereto projected part 6 of the normal growing space. The roof part 2 is present above the projected space 6. The vertical part 6 is most often at least for a significant part formed by the space between two frame girders of a green house.

In figure 1A there is further included a third screen which serves for the filtration of undesired, at least relatively less desired parts of the spectrum of sun light. In this manner plants may be provided with extra illumination by a specific part of the sun light spectrum, e.g. may be provided with additional UV-light, by inhibiting somewhat the other parts of the spectrum and by elongating the duration of illumination of the crop, or by reducing the amount of shadowing.

Preferably, at each of the three screenings by which a screening arrangement according to the inventions may be embodied, the shadowing screening 5, the airing screening 4, and the colour screening 7, the screening is produced in two screen parts shift-able relative to each another in a direction within the screening plane. Nevertheless, e.g. the colour screening may be produced in a single, preferably air permeable layer which can be folded and unfolded in the usual manner. The colour screening 7 may be integrated with the airing screening 4. At such it then forms one of both layers of the screening.

Each of both layers of a screening 4, 5, 7 that is produced in two layers is provided with a number of parts which comes free, or is activated by mutual shifting of a screening part. Such shifting takes place within the plane of screening. The parts, in principle may have any shape, as long as they are attuned to a mutual shifting direction, and as long as they are incorporated in a regular pattern. Preferably the parts are produced as transversely to the direction of movement of the screen oriented panels. This will be indicated closer along the figures 2 and 3.

The figures 2A-2C schematically show a possible embodiment of a two-fold produced light screening 5 in several positions.. In position A, the parts 5A and 5B are in such a mutually shifted position, that an adjoined deck is created which in vertical direction has an equal transmissibility. In the case where the parts 5A are produced as a light reflecting screen part, this means that the growing space is darkened by the screening 5. In the case where the parts 5A have a shadowing percentage of 60%, and parts 5B e.g. 30%, this means that the effective shadowing percentage will be higher than 60%, and less than 90%, depending of the type of cloth that are applied in the relevant parts 5A and 5B. The shadowing percentages vary in a corresponding manner in the positions according figures 2B and 2C. It is important at this embodiment to have the panels as small as possible, so as to prevent uneven growth of the crop. With the known screening cloths, e.g. from Ludvig Svensson, the configuration according to the invention can not be realised since the panels of the known cloths are produced in a different order of width, i.e. too small. These known cloths, e.g. LS16, can not be applied in a to be controlled double screening 5 because the accuracy of control of the screening arrangement is within the same order of magnitude as the width of the panels in the known cloth, namely 1 to a few centimetres.

In the case where the panels 5A of figure 2 are in non transmissible, e.g. as a reflecting screening part, the shadowing percentage in this example is of course considerably smaller, varying from 100% in figure 2A to 65% in figure 2C. The preceding examples each time departed from an equal width of the panels 5A and 5B. The width of each of the panels 5A and 5B can according to the invention however, be adapted to each indifferent width as from 5 cm. A practical upper boundary will according to the invention however be found at around 100 cm. Larger width are possible, but get remote somewhat from a goal of the invention, namely to have a swiftly controllable screening.

In the figures 3A to 3F, again a further embodiment of the invention is provided, namely a light screening 5, produced in three parts I, II, III. In this, a possible manner of shadowing is illustrated, which can vary from 0% - at which all screening parts are folded, i.e. are "packed" - to 100%, at which the screening is totally non-transmissible. The description of this example departs from a screening 5 at which the parts 5A are non-transmissible for light, and the parts 5B are transparent, e.g. open. Open may in this context be such that the non-transparent parts are mutually still connected, e.g. by fine threads, which makes the shifting of parts I, Il and III easier, particularly because these are normally incorporated mutually virtually supporting. The cloths I, II, III, are then preferably still separated from one another by guiding treads oriented in the direction of shifting, so-called atlas threads. These are not represented in the figure.

In figure 3A, the cloths I and Il are "on package", while screening part III is in an unfolded condition. This arrangement of the screening arrangement according to the invention provides a shadowing of 20% as a consequence of the width ratio between the closed panels 5A-III and 5B-III. In condition 3B also the screening part Il is unfolded, which, in the represented , overlapping condition provides a shadowing of 30 to 50%, depending on the width of the closed panels 5A-H. In figure 3C the panels 5A-

Il and 5A-III are positioned mutually aligned, which renders a shadowing percentage of 30 to 50%, depending from the amount in which the parts 5A-II and 5A-II are still positioned overlapping.

In the case that all three screening layers i-lll are unfolded, shadowing percentages of between 50% and 100% are possible, depending on the magnitude in which the three closed parts of each of the three screening layers are positioned overlapping, and/or depending on the width of the non-transmissible layer 5A-I, as in the example of figure 3D. In figure 3E a shadowing percentage of 80% is realised , and in figure 3F of 100%. In a similar manner a percentage of 70% can be attained if in the arrangement of figure 3E screening I would have been shifted, and can all kind of variations be attained in a relatively swift manner, dedicatedly adapted to requirements of the crop and the actually prevailing weather conditions. It goes without saying that also in the embodiment of figure 3 all kind of variations in shadowing and type of elimination - scattered or directly - can be brought about by varying the nature of the cloth parts 5A and 5B. In this way, in case total darkening is not relevant, a very specific shadowing can be attained by combining cloth parts 5A of different type and shadowing, and can also the cloth parts 5B be filled with a more or less kind of shadowing cloth, possibly in dependence of the layer in which this part is included.

Figure 4 illustrates a further detail from which the difference with the known screening arrangements appears, In the known arrangements, the screening is only at one end provided with a so-called drag-bar 9A, a relatively stiff profile to which the end of the cloth is attached, and by which the cloth of the screening is handled, i.e. is taken along by an incidentally not represented control organ of the screening arrangement. At a screening layer of ^n arrangement according to the invention, the cloth of at least one of the screening layers provided with two drag bars, at which the second drag bar 9B is located at the near the fixed end of a layer. The fixed end is provided with a non- transmissible cloth part 5C between the second drag bar 9B and the relevant frame girder 10 of a greenhouse. The second drag bar 9B enables the relevant screening layer to shift into two directions, and the non-transmissible part 5C provides the required shifting space without loosing closing contact with the frame girder 10. In the first, upper part of the figure, the screening is "on frame girder", i.e. in a folded condition. The second figure part illustrates the unfolded stance, and the third part a somewhat retracted screening for varying the transmissibility .

Figure 5 illustrates a first further elaboration of a cloth adapted for use in an arrangement according to the invention. Between both layers a flexible connection 11 is provided , which prevents the cloth parts to be blown apart too much. The flexible connection is however, of sufficient length to enable a cloth part 5A or 5B, with which it is connected, to shift in a manner as described in the preceding. The connection is normally composed of the same, or alternatively of one of the materials for the other functions of the cloth, and can e.g. be shaped as strip or thread. Preferably, in a screening, a many-fold of such flexible connections is incorporated. In the, in figure 5 upper arrangement, the screening, when embodied as a light screening with non transmissible parts 5A, is fully closed, en the connecting element is in a non-hindering position for light. This is also valid for the for 50% opened position in the lower figure part, where the connection element is located between the closed parts of the both layers of the screening. In the shown embodiment, preferably all panels of at least corresponding types of both layers are mutually connected.

A second further embodiment of a cloth according to the invention is represented in figure 6. In this, at least in one direction, preferably the direction of shifting, threads of the cloth are embodied elastically, and connected to a type of panel, e.g. 5A. The connections are in the figure represented by circular shapes, while the direction of movement of the threads concurs with a vertical line in the drawing. The vertical treads are turn by turn retracted in the opposite direction. At pulling of the threads, the in between opne part of the cloth enlarges.

Claims

1. Screening arrangement for screening of crops in a greenhouse (1), which arrangement comprises at least on screening (4, 5, 7) which can be brought in a folded and an unfolded condition by means of a control element pertaining to the arrangement, such as back and forth moving rod or cable, which control part is activated preferably by an automatic actuator, and is in particular provided with an electronic control unit therefore, characterized in that the screening (4, 5, 7) at least comprises cloths incorporated in the arrangement in separate layers, which cloths are each provided with several parts (A₁ B) of a distinguishing transmissibility for light or alternatively for air, and which screening parts, by mutual shifting, realise an adaptation in the amount of transmissibility therefore.

2. Arrangement volgens condusie 1 , characterized in that the parts (A, B) are composed of several, crosswise to the direction of movement of the control element extending panels, preferably such that a panel (A), in the direction of shifting of the control element, is each time alternated with a panel (B) of a distinguishing transmissibility.

3. Arrangement according to 1 of 2, characterized in that at least one of the layers is composed of a type of screening cloth known per se, such as Ludvig Svensson LS 16 of Ludvig Svensson SLS 10 ULTRA PLUS.

4. Arrangement according to one of the preceding claims, characterised in that at least one of the types, of panels (A, B) is fully transmissible either for light or for air.

5. Arrangement volgens the preceding claim, characterized in that at least the upper face of the non-transmissible panel (A) is embodied reflecting.

6. Arrangement according to one of both preceding claims, characterized in that at least the lower face of the no-transmissible panel (A) is embodied light absorbing, e.g. by embodiment is a black colour.

7. Arrangement according to one of both preceding claims, characterized in that a for light non transmissible panel (A) is at each face embodied correspondingly.

8. Arrangement according to one of the preceding claims characterised in that a for light none transmissible panel (A) is embodied by application of a band of so-called aluminium cloth.

9. Arrangement according to one of the preceding claims, characterised in that the parts (A, B) of distinguishing transmissibility mutually alternate in a regular pattern.

10. Arrangement according to one of the preceding claims, characterised in that the panels (A, B) in the cloth are provided in a width within the range of 5 to 100 cm.

11. Arrangement according to the preceding claim, characterized in that the width of the panels of at least one layer are within the range of 5 tot 20 cm, preferably are circa 10 cm.

12. Arrangement according to one of the preceding claims, in which the screening composes an air screening, characterized in that the width of the panels is within the range of 1 mm to 20 mm.

13. Arrangement according to one of preceding claims in which the screening is an air screening, characterized in that the transmissible panels are provided with perforations with a surface equal to that of a circular perforation having a diameter in the range of 1 tot 20 mm.

14. Arrangement according to one of the preceding claims, characterised in that the arrangement is provided with control means for mutually independently controlling screenings (I, II, lll)arranged in combination, in the direction of opening.

15. Arrangement according to one of the preceding claims, characterised in that the transparent panels in the cloths of the screenings layers (I, II, III) that are arranged within mutual near vicinity have, a distinguishing transmissibility for light.

16. Arrangement according to one of the preceding claims, characterised in that the screening layers (I, II, III) that are arranged within mutual near vicinity in the screening arrangement, e.g. supporting on one another, at least lying in the case of horizontal use in an upper part of a greenhouse, or mutually hang against one another in case of vertical use.

17. Arrangement according to the preceding claim, characterized in that the transparent panels of an underneath cloth (I), i.e. screening layer, has a higher transmissibility for light than the light-transmissible panels in a higher screening layer (III)-

18. Arrangement according to one of the preceding claims, characterised in that non permissible parts (A) of a screening (I) in a lower, or alternatively inner situated screening (I) are composed wider than the corresponding panels (A) of a higher, or alternatively outwardly situated screening (III).

19. Arrangement according to the preceding claim, characterized in that in vertical direction, the screening parts are mutually separated by a layer of supporting threads, incorporated at a mutual distance.

20. Arrangement according to one of the preceding claims, characterised in that a screening layer is at two end provided with a so-called drag-bar.

21. Arrangement according to one of the preceding claims, characterised in that the layers of a screening are mutually connected by flexible connecting means.

22. Arrangement according to one of the preceding claims, characterised in that the arrangement comprises at least two levels of mutually co-operating types of screenings, in particular a level of transparent cloth, directed to the regulation of air, and a level of cloths directed to the interception, and/or diffuse spreading of light.

23. Arrangement according to the preceding claim, characterized in that the air regulating level is incorporated at the lower side of the light regulating level of the screening arrangement.

24. Screening cloth, in particular for application in a screening arrangement according to one of the preceding claims, characterised in that the cloth is composed of at least two, in a mutual pattern alternating layers of distinguishable transmissibility for at least one of light en air.

25. Screening cloth according the preceding claim, characterized in that at least the least permissible parts in a cloth are composed of panels with a width of at least 5 cm, preferably circa 10 cm, en at most have a width of 100 cm.

26. Screening cloth according to one of both preceding claims, characterized in that the transmissibility of at least a panel of a cloth is nil.

27. Screening cloth according to the relevant preceding claim, characterized in that a non-transmissible panel for light, is embodied reflective at its upper face.

28. Screening cloth according to the preceding claim, characterized in that the for light non-transmissible panel, at a face facing to another layer, is embodied black, at least light-absorbing.

29. Screening cloth according to one of the relevant preceding claims, characterized in that the both faces of the for light non-transmissible panels are embodied in an according manner, in particular in black.

30. Screening cloth according to one of the preceding relevant claims, characterized in that the light reduction by a transparent panel is within in the range of

10 tot 50%.

31. Screening cloth according to one of the preceding relevant claims, characterized in that the cloth in the transparent panels is composed by an open yam weave.

32. Screening cloth according to one of the preceding relevant claims,, characterized in that the for light non-transmissible panels comprise an aluminium band.

33. Screening cloth according to one of the preceding relevant claims, characterized in that the panels compose a regular pattern in the cloth.

34. Screening cloth according to one of the preceding relevant claims, characterized in that the panels with a distinguishing transmissibility for light have a corresponding width.

35. Screening cloth according to one of the preceding claims, characterised in that the cloth has at least three mutually in a regular pattern alternating parts of distinguishing transmissibility for light or alternatively for air.