NL2020475B1 - Screen with head rail, bottom rail and middle rail and a first control unit for the middle rail and a second control unit for the bottom rail - Google Patents

Abstract

The invention relates to a screen, comprising a first control unit (610) comprising a first drive shaft (612) and at least one first cord spool (630) rotatable with the first drive shaft for winding and unwinding a first lift cord (634) extending between a head rail and a middle rail; a second control unit (620) comprising a second drive shaft (622), and at least one second cord spool (632) rotatable with the second drive shaft for winding and unwinding a second lift cord (636) extending between the head rail and the bottom rail; and a shaft rotation limiting system (100) comprising a threaded shaft arranged on and rotatable in unison with one of the first and the second drive shafts, a coupling element threaded on said threaded shaft, wherein the coupling element is associated with and rotatable in unison with the other drive shaft.

Description

Patent center

Θ 2020475

(2?) Application number: 2020475 (22) Application submitted: 22 February 2018

Int. Cl .:

E06B 9/322 (2019.01) E06B 9/262 (2019.01)

0 Priority: 0 Patent holder (s): July 25, 2017 NL 2019347 COULISSE B.V. to Enter. 0 Application registered: 0 Inventor (s): February 18, 2019 Thomas Johan Maria ter Haar in Hengelo. Bastiaan Franciscus Klein Tuente in Groenlo. 0 Request published: Harry Davids in Utrecht. 0 Patent granted: 0 Authorized representative: February 18, 2019 C.H. Mink-Lindenburg in The Hague. 0 Patent issued: May 15, 2019

SCREEN WITH HEAD RAIL, BOTTOM RAIL AND MIDDLE RAIL AND A FIRST CONTROL UNIT FOR THE MIDDLE RAIL AND A SECOND CONTROL UNIT FOR THE BOTTOM RAIL

The invention relates to a screen, including a first control unit (610) including a first drive shaft (612) and at least one first cord spool (630) rotatable with the first drive shaft for winding and unwinding a first lift cord (634) extending between a head rail and a middle rail;

a second control unit (620) including a second drive shaft (622), and at least one second cord spool (632) rotatable with the second drive shaft for winding and unwinding a second lift cord (636) extending between the head rail and the bottom rail;

and a shaft rotation limiting system (100) including a threaded shaft arranged on and rotatable in unison with one of the first and second drive shafts, a coupling element threaded on said threaded shaft, asking the coupling element is associated with and rotatable in unison with the other drive shaft.

NL B1 2020475

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

SCREEN WITH HEAD RAIL, BOTTOM RAIL AND MIDDLE RAIL AND A FIRST CONTROL UNIT FOR THE MIDDLE RAIL AND A SECOND CONTROL UNIT FOR THE BOTTOM RAIL

The present invention relates to a screen, such as a window covering including a head rail, a bottom rail movable with respect to the head rail; a middle rail arranged movably between the head rail and the bottom rail and at least one collapsible screen material supported by the middle rail and the bottom rail.

A screen according to the preamble is known in the art and is provided with a first control unit for operating the middle rail and a second control unit for operating the bottom rail. Examples of such a known screen with two control units include a Top Down / Bottom Up System or a Day Night System.

According to the invention the first control unit comprises a first drive shaft, first control means for rotating said first drive shaft, at least one first winding element rotatable with the first drive shaft for winding and unwinding a first lift cord extending between the head rail and the middle rail and the second control unit comprises a second drive shaft, second control means for rotating said second drive shaft and at least one second winding element rotatable with the second drive shaft for winding and unwinding a second lift cord extending between the head rail and the bottom rail through the middle rail and the screen material.

In the known screen the middle rail and the bottom rail move in the same plane. During operation of the first control unit for lowering the middle rail, the bottom rail is hanging still at a random position in the same plane and the middle rail will abut, but cannot pass the bottom rail. Vice versa during operation of the second control unit for raising the bottom rail the middle rail is hanging still at a random position on the same plane. In the latter situation, the moving bottom rail can drag the stationary middle rail along. In both situations, the cords of the middle rail will lose their tension and can become entangled resulting in knots. , The screen will no longer function properly.

The invention has for its object to prevent the above disadvantages.

For this purpose the screen is provided with a shaft rotation limiting system including a threaded shaft arranged on and rotatable in unison with one of the first and second drive shafts and a coupling element threaded on said threaded shaft element is associated with and rotatable in unison with the other drive shaft.

The coupling element of the shaft rotation limiting system continuously couples the first drive shaft and the second drive shaft and effectively maintain a minimum distance between the middle rail and the bottom rail to prevent loss of tension in the lift cords. Advantageously the shaft rotation limiting system according to the invention is suitable for coupling drive shafts in different configurations, such as parallel drive shafts or drive shafts lying in line.

According to a first preferred embodiment the shaft rotation limiting system further comprises a toothed shaft arranged on and rotatable in unison with the other drive shaft, the coupling element is a toothed nut that is in continuous engagement with the toothed shaft. In the first preferred embodiment the shaft rotation limiting system continuously couples parallel oriented first and second drive shafts.

According to a further preferred embodiment the toothed nut takes up a predetermined catch position on the threaded shaft and the toothed nut moves out of the catch position upon rotation or either the first shaft or the second shaft and the toothed nut moves towards the catch position upon rotation of the other (second or first) shaft. The toothed nut takes up the catch position every time the middle rail and the bottom rail meet at the minimum distance. This can be anywhere on the plane or the screen.

In a practical elaboration of the first preferred embodiment the first drive shaft and the second drive shaft rotate in opposite directions for moving the middle rail and the bottom rail in the same direction, facilitating the toothed nut moving out of and into the catch position.

In an elegant preferred embodiment the toothed nut is translatable along the toothed shaft upon rotation or the threaded shaft.

In another elegant preferred embodiment, the toothed nut is rotatable along the threaded shaft upon rotation or the toothed shaft.

In another preferred embodiment the screen according to the invention comprises a housing, the shaft rotation limiting system is accommodated. The housing allows for easy mounting of the shaft rotation limiting system in the head rail or a screen.

In yet another preferred embodiment the threaded shaft and the toothed nut are provided with cooperating first arrest means defining the predetermined catch position.

According to a second preferred embodiment of the shaft rotation limiting system the coupling element is a sleeve arranged on and rotatable in unison with the other drive shaft. In the second preferred embodiment the shaft rotation limiting system continuously couples first and second drive shafts that are oriented in line.

Preferably the threaded shaft and the threaded sleeve are provided with cooperating second arrest means defining the predetermined catch position.

In a further preferred embodiment at least one additional collapsible screen material is supported by the middle rail and the head rail.

In a preferred embodiment that is optimized for home automation the first and / or the second control means are motorized.

The invention will now be described in more detail with reference to the figures, in which:

Figure 1 shows a schematic view of a first preferred embodiment or a screen according to the invention;

Figure 2 shows the screen of Figure 1 with exploded parts;

Figure 3A schematically shows part of Figure 2 in more detail in a catch position;

Figure 3B schematically shows the part of Figure 2 in more detail in a position slightly out of the catch position;

Figure 3C schematically shows the part of Figure 2 in more detail in an end position;

Figures 4A-D are cross sections through the part of figures 3A-3C;

Figure 5 shows a schematic view or a second preferred embodiment or a screen according to the invention;

Figure 6 shows the screen of Figure 5 with exploded parts;

Figure 7A schematically shows part of Figure 6 in more detail in a catch position;

Figure 7B schematically shows the part of Figure 7A in top view;

Figure 7C schematically shows the part of Figure 7A in the cross section;

Figure 7D schematically shows the part of Figure 6 in more detail in an end position;

Figure 7E schematically shows the part of Figure 7D in cross section;

Figure 8 shows a schematic view of a third preferred embodiment or a screen according to the invention;

Figure 9 shows a schematic view of a fourth preferred embodiment or a screen according to the invention;

Figure 10 shows a schematic view of a fifth preferred embodiment or a screen according to the invention; and

Figure 11 shows the screen of Figure 10 with exploded parts.

The same components are designated in the different figures with the same reference numerals.

Figure 1 shows a schematic view of a first preferred embodiment or a screen 1 according to the invention. The screen 1 is a window covering, more specifically a top down, bottom up honey cell blind.

The window covering 1 comprises a head rail 2 and a bottom rail 6 that is movable with respect to the head rail. A middle rail 4 is arranged movably between the head rail and the bottom rail. The screen has at least one collapsible screen material 8 that extends between the middle rail 4 and the bottom rail 6.

Figure 2 shows the screen 1 with exploded parts. A first control unit 10 controls the middle rail and comprises a first drive shaft 12 extending into the head rail 2. First control means for rotating said first drive shaft 12 comprising a chain or cord 14, a gear 16 and a transmission 18. One or more first cord spools 30 are arranged on the first drive shaft 12 for winding and unwinding one or more first lift cords 34 extending from the head rail 2 to the middle rail 4.

A second control unit 20 controls the bottom rail 6 and comprises a second drive shaft 22 extending into the head rail 2 parallel to the first drive shaft 12. Second control means for rotating said second drive shaft 22 comprising a chain or cord 24 and a gear 26. One or more second cord spools 32 are arranged on the second drive shaft 22 for winding and unwinding one or more second lift cords 36 extending between the head rail 2 and the bottom rail 6 through the middle rail 4 and the screen material 8.

The number of cord spools 30 respectively 32 and corresponding lift cords 34 respectively 36 on each drive shaft 12 or 22 may vary depending on the size of the screen. In the first preferred embodiment the number is three. One example of a suitable cord spool is described in the European patent EP2589743 or the same applicant.

According to the invention a shaft rotation limiting system is provided. A first preferred embodiment of the shaft rotation limiting system 100 is shown in figures 3A-3C in more detail. A second preferred embodiment of the shaft rotation limiting system 300 is shown in Figure 7A-7E in more detail.

In general, the shaft rotation limiting system 100 or 300 comprises a threaded shaft 102 or 302 that is arranged on and rotatable in unison with either the first or second drive shaft 12 or 22 or 312 or 322. A coupling element is threaded on said threaded shaft 102 or 302 and is associated with and rotatable in unison with the other drive shaft 22 or 12 or 322 or 312 respectively.

In the first preferred embodiment shown in figures 3A-3C the threaded shaft 102 is arranged on and rotatable in unison with the first drive shaft 12. The shaft rotation limiting system 100 further comprises a toothed shaft 106 that is arranged on and rotatable in unison with the second drive shaft 22.

The coupling element comprises a toothed nut 104 that is threaded on the threaded shaft 102 and is in continuous engagement with the toothed shaft 106. The threaded shaft 102 has an outer screw thread and the nut 104 has an inner screw thread. The outer screw thread and the inner screw thread fit together.

The toothed shaft 106 is an elongated gearwheel or sprocket wheel and can be compared to many gear wheels or sprocket wheels arranged in line. Preferably the cross section through the toothed shaft 106 is substantially uniform over the entire length of the toothed shaft 106. The toothed nut 104 and the toothed shaft 106 have a mating toothing, i.e. with the same modulus. Preferably the toothing is straight.

The operation of the shaft rotation limiting system 100 will be elucidated referring to figures 4A-D that show cross sections through the shaft rotation limiting system 100 at the position of the nut 104 as seen in the direction of view V. The position of the toothed nut 104 in figure 3A is referred to as the catch position. In figure 3B the toothed nut 104 has just left the catch position or figure 3A. The position in figure 3C is referred to as the end position.

In figure 4A the second control means are operated to lower the bottom rail 6. The second drive shaft 22 is rotated clockwise as indicated by the arrow A. The toothed shaft 106 rotates in the same direction (clockwise). Because of the continuous engagement with the toothed shaft the toothed nut 104 is rotated along the threaded shaft 102 and leaves the predetermined catch position of figure 3A.

In figure 4B the second control means are operated to raise the bottom rail 6. The second drive shaft 22 is now rotated counter clockwise as indicated by the arrow B. The toothed shaft 106 rotates in the same direction (counter clockwise). Because of the continuous engagement with the toothed shaft 106 the toothed nut 104 is rotated along the threaded shaft 102 and returns to the predetermined catch position of figure 3A.

In figure 4C the first control means are operated to lower the middle rail 4. The first drive shaft 12 is rotated counter clockwise as indicated by the arrow C. The threaded shaft 102 rotates in the same direction (counter clockwise). Because of the continuous engagement with the toothed shaft 106 the toothed nut 104 is translated along the toothed shaft towards the predetermined catch position of figure 3A.

In figure 4D the first control means are operated to raise the middle rail 4. The first drive shaft 12 is rotated clockwise as indicated by the arrow

D. Turn, the threaded shaft 102 rotates in the same direction (clockwise). Because of the continuous engagement with the toothed shaft 106 the toothed nut 104 is translated along the toothed shaft 106 out of the predetermined catch position of figure 3A.

In the first preferred embodiment the shaft rotation limiting system 100 is accommodated in a housing or cradle 110. The cradle has a bearing function for the shaft 102 and the shaft 106 and has an adaptive function with respect to mounting in the head rail.

The threaded shaft 102 and the toothed nut 104 are provided with cooperating first arrest means defining the predetermined catch position. At the side of the threaded shaft 102 a first stop or catch 108 is arranged to define the catch or stop position for the toothed nut 104. The toothed nut 104 is for this purpose provided with a first cam 107 for cooperation with the catch 108.

The toothed nut 104 takes up the catch position every time the middle rail 4 and the bottom rail 6 measures. In the first preferred embodiment the first drive shaft 12 and the second drive shaft 22 rotate in opposite directions (clockwise and counter clockwise or vice versa) for moving the middle rail 4 and the bottom rail 6 in the same height direction (up or down) . The threaded shaft 102 engages the toothed nut 104 on the inner side fortranslation along the toothed shaft 106 to any current position. The toothed shaft 106 engages the toothed nut 104 on the outer side for rotation around and consequently translation along the threaded shaft 106 to any current position. The distance between the current position and the catch position sets a maximum distance the middle rail 4 can travel towards the bottom rail 6 or the bottom rail 6 can travel towards the middle rail 4.

The shaft rotation limiting system 100 couples the first drive shaft 12 and the second drive shaft 22 and ensures a minimum distance between the middle rail 4 and the bottom rail 6 to prevent loss of tension in the lift cords.

Figure 5 shows a schematic view or a second preferred embodiment or a screen 201 according to the invention. The screen 201 is a window covering, more specifically a top down, bottom up honey cell blind. When compared to figure 1 corresponding components are designated with corresponding reference numerals raised by 200.

The window covering 201 comprises a head rail 202 and a bottom rail 206 that is movable with respect to the head rail. A middle rail 204 is arranged movably between the head rail and the bottom rail. The screen has at least one collapsible screen material 208 that extends between the middle rail 204 and the bottom rail 206.

Figure 6 shows the screen 201 with exploded parts. A first control unit 210 controls the middle rail and comprises a first drive shaft 212 extending into the head rail 202 and a chain or cord 214. The first control means are preferably arranged as a breakaway device for the chain 214 in view of child safety. One example of a suitable breakaway device is described in the European patent EP2574717 or the same applicant. One or more first cord spools 230 are arranged on the first drive shaft 212 for winding and unwinding one or more first lift cords 234 extending from the head rail 202 to the middle rail 204.

A second control unit 220 controls the bottom rail 206 and comprises a second drive shaft 222 extending into the head rail 202 in line with the first drive shaft 212. Second control means for rotating said second drive shaft 222 further comprising a chain or cord 224. The second control means preferably arranged as a breakaway device for the chain 224 in view of child safety. One example of a suitable breakaway device is described in the European patent EP2574717 or the same applicant. One or more second cord spools 232 are arranged on the second drive shaft 222 for winding and unwinding one or more second lift cords 236 extending between the head rail 202 and the bottom rail 206 through the middle rail 204 and the screen material 208.

The number of cord spools 230 respectively 232 and corresponding lift cords 234 respectively 236 on each drive shaft 212 respectively 222 may vary depending on the size of the screen. In the second preferred embodiment the number is two. The second cord spools 232 are mirrored with respect to the first cord spools.

According to the invention a shaft rotation limiting system 300 is provided. A second preferred embodiment of the shaft rotation limiting system 300 is shown in figures 7A-7E in more detail. When compared to figure 3 corresponding components are designated with corresponding reference numerals raised by 200.

In general, the shaft rotation limiting system 300 comprises a threaded shaft 302 that is arranged on and rotatable in unison with either the first or the second drive shaft 212 or 222. A coupling element 304 is threaded on said threaded shaft 302 and is associated with and rotatable in unison with the other drive shaft 222 respectively 212.

In the second preferred embodiment shown in figure 5 the threaded shaft 302 is arranged on and rotatable in unison with the second drive shaft 222. The coupling element is a sleeve 304 arranged on and rotatable in unison with the first drive shaft 212. The sleeve 304 has an inner passageway 305 for the first drive shaft 212. The inner passageway 305 is arranged such that the sleeve 304 can move in axial direction to slide over the first drive shaft 212. In the inner passageway 305 one or more ridges 306 are provided that allow the first drive shaft 212 to take the sleeve 304 along during rotation.

The coupling element 304 is in continuous engagement with the threaded shaft 302. The threaded shaft 302 has an outer left-handed screw thread and the sleeve 304 has an inner left-handed screw thread. The outer screw thread and the inner screw thread fit together.

The operation of the shaft rotation limiting system 300 will be elucidated referring to figures 7A-7E that show schematic views of and cross sections through the shaft rotation limiting system 300. The position in figure 7A is referred to as the catch position. The position in figure 7D is referred to as the end position.

In figure 7A the shaft rotation limiting system 300 is in the catch position, the distance between the middle rail 204 and the bottom rail 206 is minimal. When the second control means are operated to lower the bottom rail 206, the second drive shaft 222 and the threaded shaft 302 are rotated clockwise as seen from the direction of view V. Because of the continuous engagement with the threaded sleeve 304 the threaded shaft 302 leaves the predetermined catch position and can take any current position between the catch position of figure 7A and the end position of figure 7D.

When the shaft rotation limiting system 300 is in the end position of figure 7D the distance between the middle rail 204 and the bottom rail 206 is maximum, as seen in figures 5 and 6.

Starting from the end position of figure 7D the first control means can be operated to lower the middle rail 204. The first drive shaft 212 and the sleeve 304 are rotated clockwise as seen from the direction of view V. Because the threaded sleeve is 304 rotated along the threaded shaft 302 and can take up any current position between the end position of figure 7D and the catch position of figure 7A.

When the shaft rotation limiting system 300 has returned to the catch position of figure 7A the bottom rail 206 and the middle rail 204 are at the minimum distance.

Raising of the middle rail 204 involves operating the first control means. The first drive shaft 212 and the sleeve 304 are rotated counter clockwise as seen from the direction of view. V., the threaded sleeve 304 is rotated along the threaded shaft 302 and can take any current position between the catch position of figure 7A and the end position of figure 7D.

Raising of the bottom rail 206 involves operating the second control means. The second drive shaft 222 and the threaded shaft 302 are rotated counter clockwise as seen from the direction of view V. Because of the continuous engagement with the threaded sleeve 304 the threaded shaft 302 returns to the predetermined catch position and can take up any current position between the end position of figure 7D and the catch position of figure 7A.

In the second preferred embodiment the shaft rotation limiting system 300 is accommodated in a housing or cradle 310. The cradle has a bearing function for the shaft 302 and the sleeve 304 and has an adaptive function with respect to mounting in the head rail.

The threaded shaft 302 and the threaded sleeve 304 are provided with cooperating second arrest means defining the predetermined catch position. At the end of the outer thread of the threaded shaft 302 a second stop or catch 308 is arranged to define the catch or stop position for the threaded sleeve 304. The threaded shaft 304 is for this purpose provided with a second cam 307 for cooperation with the catch 308 shown in top view in figure 7B.

The shaft rotation limiting system 300 couples the first drive shaft 212 and the second drive shaft 222 and limits the height movement of the middle rail and the bottom rail with respect to each other. Effectively loss of tension in the cords of the middle rail 204 is prevented when one of the rails is attempting to pass the position of the other rail during raising or lowering.

The sleeve 304 and threaded shaft 302 take up the catch position every time the middle rail 204 and the bottom rail 206 measure. In the second preferred embodiment the first drive shaft 212 and the second drive shaft 222 rotate in the same direction to either lower (clockwise) or raise (counter clockwise) the operated rail as seen from direction or view V. The threaded shaft 302 and the threaded shaft 304 can take up any current position between the catch position of figure 7A and the end position of figure 7D. The distance between the current position and the catch position is a measure for the maximum distance the middle rail 204 can travel towards the bottom rail 206 or the bottom rail 206 can travel towards the middle rail 204.

Summarizing the second embodiment shows shafts 212, 222 that are arranged in line and are hero in continuous engagement by means of a shaft rotation limiting system 300. The shaft rotation limiting system 300 comprises a threaded shaft 302 arranged on and rotatable in unison with one of the first and the second drive shafts 212 respectively 222 and a coupling sleeve 304 threaded on said threaded shaft 302 that is associated with and rotatable in unison with the other drive shaft 222 or 212 respectively.

The shaft rotation limiting system 300 limits raising the bottom rail 206 beyond the position of the middle rail 204 as well as lowering the middle rail beyond the position of the bottom rail. The actual position of the coupling sleeve 304 with respect to the catch position is a measure of the distance between the middle rail and the bottom rail.

Figure 8 shows a schematic view of a third preferred embodiment or a screen 401 according to the invention. The third preferred embodiment is based on the first preferred embodiment shown in Figure 1, at least one additional collapsible screen material 409 is supported by the middle rail 404 and the head rail 402. When compared to figure 1 corresponding components are designated with corresponding reference numerals raised by 400.

Figure 9 shows a schematic view of a fourth preferred embodiment or a screen 501 according to the invention. The fourth preferred embodiment is based on the second preferred embodiment shown in Figure 5, at least one additional collapsible screen material 509 is supported by the middle rail 504 and the head rail 502. When compared to figure 5 corresponding components are designated with corresponding reference numerals raised by 500.

The screens of figures 8 and 9 are also known as a Day Night System.

Figure 10 shows a schematic view of a fifth preferred embodiment or a screen 601 according to the invention. Figure 11 shows the screen of figure 601 with exploded parts. The screen 601 is a window covering, more specifically a top down, bottom up honey cell blind.

The screen 601 differs from the screen 1 shown in figures 1 and 2 in that the control means are motorized. The first control means include a motor 611 instead of a chain or cord, a gear and a transmission. The second control means include a motor 621 instead of a chain or cord and a gear. In the preferred embodiment shown the motor is a by pull (de-) activated motor having a chain 614 or 624. One example of a suitable by pull (de-activated) motor is the motor described in the Dutch patent 2016447 of the same applicant . Alternatively a motor with an antenna for receiving RF signals from a remote control or a wall switch can be used.

The reference numerals of all other elements of the screen 601 are raised with the number 600 with respect to the reference numbers of the corresponding elements of the screen 1.

In the fifth preferred embodiment the screen 601 is provided with the first preferred embodiment of the shaft rotation limiting system 100 that continuously couples parallel oriented first and second drive shafts 612, 622.

Alternatively, a further preferred embodiment (not shown) or a motorized screen can be provided with the second preferred embodiment of the shaft rotation limiting system 300 that continuously couples drive shafts lying in line. Such a further preferred embodiment would require a longer rail.

The invention provides a shaft rotation limiting system for a screen with a head, middle and bottom rail that can move in and out of a catch position, the distance between the middle rail and the bottom rail is at a minimum. Starting from the catch position all lowering operations require the bottom rail to be lowered first before the middle rail can be lowered and all pulling operations require the middle rail to be pulled up before the bottom rail can be pulled up.

The invention is of course not limited to the described and shown preferred exponent. As an example the preferred extended include cord spools for (un) winding lift cords, but the invention extends to alternative included including alternative winding elements for alternative lifting means, such as drums for lift tapes or lift bands, that are for instance used in pleated blinds.

Fall the invention extends to any edition falling within 5 the scope of protection as defined in the claims and as seen in the light of the foregoing description and accompanying drawings.

Claims (13)

CONCLUSIONS A screen, such as a window covering (1; 201; 401; 501; 601) comprising a main rail (2; 202; 402; 502; 602); a bottom rail (6; 206; 406; 506; 606) movable relative to the main rail; a center rail (4; 204; 404; 504; 604) movably arranged between the main rail and the bottom rail; at least one foldable screen material (8; 208; 408; 508; 608) carried by the center rail and the bottom rail; a first control unit (10; 210; 410; 510; 610) comprising a first drive shaft (12; 212; 612), first control means (14, 16, 18; 214; 414; 514; 611,614) for rotating the first drive shaft at least a first winding element (30; 230; 630) rotatably connected to the first drive shaft for winding and unwinding first hoisting means (34; 234; 634) extending between the main rail and the central rail; a second control unit (20; 220; 420; 520; 620) comprising a second drive shaft (22; 222; 622), second control means (24, 26; 224, 226; 424; 524; 621,624) for rotating the second drive shaft , at least one second winding element (32; 232; 632) rotatably connected to the second drive shaft for winding and unwinding second hoisting means (36; 236; 636) extending between the main rail and the bottom rail through the center rail and the screen material ; and a shaft rotation limiting system (100; 300) comprising a wire shaft (102; 302) mounted on and jointly rotatably connected to one of the first and the second drive shafts, a coupling element (104; 304) mounted on the wire shaft in which the coupling element belongs is rotatably connected to the other drive shaft. The screen of claim 1, wherein the shaft rotation limiting system (100) further comprises a toothed shaft (106) mounted on and jointly rotatably connected to the other drive shaft, wherein the coupling element is a toothed nut (104) in continuous engagement with the toothed shaft (106). The screen of claim 2, wherein the toothed nut (104) occupies a predetermined catch position on the threaded shaft (102) and wherein the toothed nut moves out of the catch position upon rotation of either the first drive shaft (12) or the second drive shaft (22) and wherein the toothed nut moves toward the receiving position upon rotation of the other axis. The screen of claim 1,2 or 3, wherein the first drive shaft (12) and the second drive shaft (22) rotate in opposite directions when the center rail (4) and the bottom rail (6) move in the same direction. 10. Screen as claimed in claim 8, wherein the wire axis (302) and the wire sleeve (304) are provided with cooperating second locking means (307, 308) which define the predetermined receiving position. Screen according to one or more of the preceding claims, wherein the toothed nut (104) is translatable along the toothed shaft (106) upon rotation of the threaded shaft (102). Screen according to one or more of the preceding claims, wherein the toothed nut (104) is rotatable about the threaded shaft (102) upon rotation of the toothed shaft (106). Screen according to one or more of the preceding claims 2 to 6, wherein the threaded shaft (102) and the toothed nut (104) are provided with cooperating first locking means (107, 108) defining the predetermined receiving position. The screen of claim 1, wherein the coupling element is a sleeve (304) mounted on and rotatable jointly with the other drive shaft. The screen of claim 8, wherein the sleeve (304) has a length that substantially corresponds to the length of the wire axis (302). 10 comprising a housing (110; 310) in which the axis rotation restriction system (100; 300) is accommodated. 11. Screen according to one or more of the preceding claims, The screen of any one of the preceding claims, wherein at least one additional foldable screen material (409; 509) is Supported by the center rail (404; 504) and the main rail (402; 502). Screen according to one or more of the preceding claims, wherein the first control means (610) and / or the second control means (620) are motorized.