DE102012011796A1 - Darkening device for covering opening with curtain, has spring breakage sensor that is located for monitoring condition of return spring and/or roll-off protection and/or electromagnetic clutch - Google Patents

Abstract

The darkening device (1) has return spring (10) that is rotatably supported on a stationary supporting frame (9). The motor shaft (19) is fixed on the axially opposite side of coupling (7). The motor shaft is rotationally fixed to the supporting frame. A spring breakage sensor (23) is located for monitoring the condition of the return spring and/or roll-off protection (41) and/or the electromagnetic clutch (14). Independent claims are included for the following: (1) darkening system; and (2) method for operating darkening device.

Description

The invention relates to a dimming device according to the preamble of claim 1, a dimming system and a method for its operation.

The DE 199 18 489 C2 discloses a generic dimming device in the form of a winding cover device with emergency winding. There, a cover sheet is arranged on a hollow and cylindrical, mutually open winding shaft. The winding shaft is seated on a spring shaft, which is connectable via a trained by pins and a disc-like latch member locking device with a driven part of a winding motor. The winding motor is arranged in a second region of the winding shaft and not attached to this, but received axially displaceable and non-rotatably with a motor pin on a stationary bearing. The free end of the motor pin is supported on a disc-like actuating element, which is rotatable about a pivot point, that it can be pulled off by means of a tension element of the motor pin. As a result, the motor pin can be released, so that the winding motor is pressed axially away from the spring shaft by a spring arranged between the spring shaft and the winding motor and the locking device is disengaged. As a result, the spring shaft with respect to the winding motor is freely rotatable and can be wound on the biased by the unwinding of the cover sheet spring shaft, especially in an emergency opening in which the cover sheet must be wound without motor drive. The emergency rewind can be triggered by hand via the tension element. It is disadvantageous that no automatic emergency opening is possible because in an emergency pulling up the cover sheet must be effected by hand.

The DE 31 32 073 A1 concerns an electric motor driven Rafflamellenstore with emergency drive. The Rafflamellenstore is actuated via an elevator shaft, which is connected via an electromagnetic clutch with a take-up motor. In this case, the clutch is connected in the supply circuit of the Aufwickelmotors that when de-energized state of the Aufwickelmotors the electromagnetic clutch is decoupled. In an emergency, in which the power fails, the Rafflamellenstore can then be rolled over a manually operated connecting rod, which is connected via a second clutch to the elevator shaft, without the take-up motor is connected to the elevator shaft. The disadvantage there is the large-scale design with stationary drive. Also, this embodiment does not allow automatic emergency opening, since in an emergency, especially in case of power failure, the Rafflamellenstore must be opened by hand.

The DE 10 2004 029 553 A1 relates to a Notraffvorrichtung for retractable and retractable curtain with a drive unit for driving a arranged on a drive shaft rortierbaren elevator organ with a drive unit shaft, a spring motor with a prestressed spring shaft, which is at one end in operative connection with the drive shaft and at its other end is supported on a fixed bearing, and a coupling for releasably coupling the drive unit shaft with the drive shaft. The drive unit shaft and the spring shaft are arranged on two parallel axes so that the drive unit and the spring motor are arranged spaced from each other and arranged between the parallel axes connecting drive the drive unit shaft and the spring shaft rotatably interconnected only when coupled coupling. The coupling is electrically operated there. Further, there are disclosed sensors for detecting a retracted and extended curtain, the signals of which can be processed by a central control of a building. In addition, the central controller can electrically actuate the electrical coupling. The disadvantage is there the complex and large-scale design because of the spaced-apart, parallel juxtaposed waves.

The object of the invention is therefore to overcome the above-mentioned disadvantages and to provide a dimming device according to the preamble of claim 1, a dimming system according to claim 16 and a method of its operation according to the preamble of claim 18, the reliable operation of the dimming device and the Verdunldungssystems, even in an emergency, especially in case of power failure, allow.

This object is achieved by the invention by a dimming device having the features of claim 1, a dimming system according to claim 16 and a method of its operation according to the preamble of claim 18. Advantageous embodiments and expedient developments of the invention are specified in the dependent claims.

According to the invention the above-mentioned darkening device is characterized in that the coupling is designed as an electromagnetic clutch, a spring breakage sensor for monitoring the state of the return spring is provided and / or a roll-off is provided.

Advantageously, the spring break sensor having a relation to the hanging shaft fixed spring shaft bearing with a sliding bearing for rotatably supporting a stub shaft of the spring shaft, wherein a blocking device prevents a complete rotation of the spring shaft, and the Shaft stub has an actuating element for actuating an electrical switch. As a result of this mounting, the stub shaft is mounted rotatably to the extent that the actuating element can switch on or release the switch.

Advantageously, the actuating element may have a measuring leg projecting from the stub shaft, which permanently actuates the electric switch when the curtain is wound up when the spring force of the return spring of the spring shaft does not fall below a predetermined lower limit value.

In an advantageous development, at least one bore provided in a plane of rotation of the measuring leg can be provided in the spring shaft bearing with an adjusting screw rotatable therein, which is connected to the measuring leg via an adjusting spring, wherein the adjusting spring exerts a force counteracting the spring force of the spring shaft on the measuring leg. In this way it can be ensured that, when the spring force of the return spring of the measuring leg is completely eliminated, the switch is lifted from the switch and thus a corresponding signal is received from the control of the darkening system, which then emits a warning signal and, if necessary, can independently move the blind upwards.

Further advantageous in the spring shaft bearing another provided in the plane of rotation of the measuring leg bore can be provided with a rotatable further adjustment screw, which is connected to the measuring leg via a further adjusting spring, wherein the further adjusting spring exerts a spring force of the spring wave equally acting force on the measuring leg. As a result, the predetermined lower limit of the spring force can be set very fine.

Preferably, the blocking device may have at least one protruding from the stub shaft, in a engaging between two legs of the spring shaft bearing blocking leg, which limits the rotation of the stub shaft sure. In principle, however, the blocking device can also be provided only by the measuring leg, but an additional blocking leg increases the reliability and enables a smaller dimensioning of the measuring leg, since the holding force for the spring shaft is divided.

Advantageously, the roll-off can have a tilting element rotatable relative to a rolling plane of the curtain around a tilt axis extending substantially parallel to the rolling plane with a rocker arm which is held in an unstable position outside the rolling plane via an energized electromagnetic holding magnet and falls into a blocking position in the rolling plane by gravity when the holding magnet is de-energized. As a result, even with electrically operated Verdunldungssystems unwanted rolling of a curtain, especially in an emergency, can be prevented.

Preferably, the center of gravity of the tilting element can be placed in the unstable position between the tilting axis and the rolling plane, so that tilting of the tilting element and thus of the tilting lever can be achieved reliably with currentless holding magnets. Advantageously, the center of gravity of the rocker arm can be placed in the unstable position above the tilt axis, so that a faster tilting is made possible. Furthermore, a stop web mounted fixedly on the darkening device can hold the rocker arm from below in the blocking position.

According to the invention, the darkening system can have a darkening device described above and below as well as guide rails for guiding the curtain between an upper and lower position of the blind and a control of the darkening system.

The above-mentioned method can drive according to the invention in response of the spring break sensor the curtain in the upper position, so that when the spring force of a return spring of the curtain is moved to the open position and an emergency exit is not blocked by the curtain. Preferably, when the spring failure sensor responds, the roll-off safety device can be activated, so that the curtain is held securely in the upper, open position, even in the event of a subsequent power failure.

The invention will now be described by way of example with reference to the accompanying drawings. These show:

1 a schematic front view of a cut-open Verdunldungsvorrichtung invention;

2 a cross section through a closed coupling device of the darkening device 1 ;

3 the view 2 with open coupling device;

4 an enlarged section of the in 1 left side of the darkening device;

5 a schematic side view from the left on the view of 4 with a spring break sensor;

6 a schematic side view from the right to the view of 1 with a roll-off protection in the open state;

7 a schematic frontal view of the roll-off 6 ;

8th the view 6 with activated roll-off protection;

9 a schematic circuit and connection diagram of a darkening system according to the invention.

1 shows a darkening device according to the invention 1 with an in 1 rolled up curtain 2 , A lower end of the blind 2 is in a hanging rail 3 attached, which with both sides over long sides of the curtain 2 protruding ends in lateral guide rails 4 and 5 is guided.

The curtain 2 is on a hollow cylindrical Behangwelle 6 attached via a clutch 7 with an electric winding motor 8th connectable. The winding motor 8th is on the in 1 right side fixed to a support frame 9 the Verdunldungsvorrichtung 1 attached. In normal operation, the blind can 2 over the winding motor 8th be moved between a fully open and a fully closed position back and forth. The training described above is already known in principle and therefore needs no further explanation.

In case of an emergency, a completely or partially closed curtain 2 Being able to roll up independently is the hanging wave 6 in a conventional manner via a return spring 10 with a spring shaft 11 connected. The spring shaft 11 is with a stub shaft 12 at an in 1 left spring shaft bearing 13 in the supporting frame 9 supported. The return spring 10 is so between Behangwelle 6 and spring shaft 11 attached, that when motorized unrolling the curtain 2 the return spring 10 is tense. In addition, the return spring 10 already with fully opened upper curtain 2 already biased so that the spring force the curtain 2 pulls up slightly. The bias and the while rolling the hangings 2 caused tension of the return spring 10 thus have the same direction of effect and add up.

In an emergency, for example, by pressing an emergency switch, the clutch 4 between hanging wave 6 and winding motor 8th solved, so causes the tensioned return spring 10 that the hanging wave 6 rolled up and thus the curtain 2 is moved to the fully open upper position. This too is principally among other things DE 199 18 489 C2 known.

In the case of known darkening devices, the curtain must be manually cranked up in an emergency, especially in the event of a power failure, or the spring-force-induced independent reeling must be triggered manually. Meanwhile, however, is required that the rolling up, if necessary, automatically, even with electric blackout devices and power failure. In addition, hand-operated, mechanically complex and space-consuming emergency cranks are to be avoided because of the risk of misuse and vandalism.

As in 2 and 3 recognizable, the invention therefore provides the known, purely mechanical, manually operated clutches by a known per se electromagnetic clutch 14 to replace. The electromagnetic clutch 14 has for this purpose an electrically excited electromagnet 15 up, over one by the spring wave 11 and the stub shaft 12 outgoing supply line 16 is supplied electrically.

An electromagnet 15 assigned coupling counterpart 17 the clutch 7 is in the axial direction of the winding motor 8th slidable on a motor mounting 18 stored, wherein the coupling counterpart for transmitting torque in the radial direction with a motor shaft 19 of the winding motor 8th is connected, for. B. by means of a driving screw 18 ' , Between coupling counterpart 17 and engine mounting 18 is a plate spring 20 trained return element provided which the coupling counterpart 17 from the electromagnet 15 moves away, wherein in the coupled state, the force of the electromagnet 15 the opposite force of the diaphragm spring 20 overcomes.

Will the electromagnet 15 energized, he pulls the coupling counterpart 17 on, pointing to each other, annular coupling edges 21 and 22 are positively connected with each other, as in 2 shown. This can be in normal operation Behangwelle 6 and winding motor 8th be firmly coupled together. In the present embodiment, the connection can be further improved when the coupling flanks 21 and 22 advantageous means of in 2 and 3 have indicated form-locking elements designed as interlocking gears, so that in addition a positive connection is provided. Instead of a toothing other form-fitting connections can be provided, for. B. sawtooth-shaped connections. Also can advantageously an additional frictional connection by friction surfaces on the coupling edges 21 to be provided. This allows the electromagnet 15 be designed weaker, since the Positive connection improves the torque transmission and additionally provides improved anti-slip protection.

Will the electromagnet 15 de-energized, either by power failure or emergency shutdown, he loses his electromagnetic holding power and the adhesion with the coupling counterpart 17 gets lost. In addition, the plate spring pulls 20 the coupling counterpart 17 from the electromagnet 15 away, leaving the coupling flanks 21 and 22 disengage.

In one embodiment of the invention, the coupling edges 21 and 22 completely or largely smooth running, so that even in the closed state of the clutch 7 no or only weak positive connection exists. In this embodiment, the coupling counterpart 17 then without a diaphragm spring 20 directly on the engine mount 18 be attached so that the structure of the electromagnetic clutch 14 simplified.

By the coupling formed as above 7 can thus be ensured that in the currentless case, the connection between Behangwelle 6 and winding motor 8th is opened. As a result, in a conventional manner, the spring shaft 11 with the tensioned return spring 10 no longer through the winding motor 5 held, so the hangings 2 automatically pulled up and rolled up and the previously by the hanging 2 completely or partially closed opening, z. As a window or a door, is released so that it can be used as an escape route.

As in 1 recognizable, is on the in 1 left side a spring breakage sensor 23 provided, which now based on 4 and 5 will be described in detail below.

This is the Wellensstummel 12 the spring shaft is not rigid, but a plain bearing 24 rotatable in the spring shaft bearing 13 stored. That over the slide bearing 24 standing out end of the stub shaft 12 extends into a hollow cylindrical widening 25 one between upwardly open thighs 26 and 27 of the spring shaft bearing 13 extending leg gap 28 so that the stub shaft 12 can rotate freely in it.

To completely spin the stub shaft 12 to prevent the spring shaft 11 would be ineffective, attacks on the one hand rotatably on the shaft stub 12 attached shorter locking leg 29 in the in 5 well-recognizable, closed down end of the leg gap 28 , One as z-shaped with the blocking leg 29 connected measuring leg 30 trained actuator engages on the opposite side of the expansion 25 in the upwardly open end of the leg gap 28 , Thus, the stub shaft 12 and consequently the spring shaft 11 at most within the through the upper and lower part of the leg gap 28 rotate certain limits.

In extension of the left thigh 27 is a known per se electrical micro-switch 31 with a switch button 32 intended. Normally, so if the return spring 10 the spring shaft 11 is not broken or their spring force is otherwise weakened, presses the preloaded return spring 10 the spring shaft 11 the stub shaft 12 in 5 in the counterclockwise direction. This will become a button 33 of the measuring leg 30 against a stop surface 34 of the microswitch 31 and thus the switch button 32 depressed, so that constantly a corresponding signal is output. Because the bias of the spring shaft 11 in 5 counter-clockwise and when rolling the curtain 2 still increased, is at functioning return spring 10 the measuring leg 30 always firmly on the switch button 32 pressed.

Advantageously, as in 5 recognizable, the button 33 be so beveled that you press the button 32 at the stop surface 34 is applied. This also causes a complete depression of the switch button 32 ensured. As in 5 clearly recognizable, touching neither the blocking leg in this position 29 still the measuring leg 30 the thigh 26 respectively. 27 ,

To the location of blocking legs 29 and measuring legs 30 in the leg gap 28 to be able to adjust are on the blocking leg 29 and measuring legs 30 formed as coil springs adjusting springs 35 respectively. 36 mounted at their other ends to trained as set screws adjusting screws 37 and 38 are attached. The adjusting screws 37 can in tapped holes 39 and 40 in the thighs 26 respectively. 27 be positioned, reducing the spring force of the adjusting springs 35 and 36 can be changed. The adjusting screw 37 is set up so that it is the blocking leg 29 in the counterclockwise direction while the adjusting screw 38 the measuring leg 30 pushes away in a clockwise direction.

For reliable detection of a spring break or decrease in the spring force of the return spring 10 become the adjusting springs 35 and 36 over the adjusting screws 37 respectively. 38 adjusted so that falls below a predetermined lower limit of the spring force of the return spring 10 with the curtain completely rolled up 2 the measuring leg 30 from the switch button 32 moved away, leaving the microswitch 31 switches over and outputs a corresponding signal.

One at the in 1 and 4 left guide rail 4 arranged and in 6 to 8th detail shown roll-off protection 41 prevents power failure and defective return spring 10 the curtain 2 from the rolled-up upper position due to gravity rolls down and closes the opening.

The roll-off protection 41 has for this purpose a one-piece formed from a sheet metal tilting element 41 ' with one around a tilt axis 42 rotatably mounted rocker arm 43 on. The tilting element 41 ' has a connecting bridge 44 with two down-pointing, U-shaped holding legs 45 . 46 on, over a the tilt axis 42 forming tilting shaft 47 on to the guide rail 4 attached retaining bars 48 . 49 are hinged. The retaining bars 48 . 49 are in turn U-shaped over a stop bridge 50 connected to each other, the further tilting of the rocker arm 43 from the blocking position in 8th prevented.

The tilting element 41 ' with rocker arm 43 is in the in 1 and 6 shown open position so on the tilt axis 42 arranged by gravity by itself in the 8th shown blocking position in a rolling plane A of the curtain 2 and in 1 recognizable to the right of the track 4 tilts. The tilting movement is still supported by the weight of the running rail 4 towards directed connecting web 44 ,

One at the roll-off protection 41 arranged electrical holding magnet 51 Holds the rocker arm 43 in normal operation in the in 6 shown opened position, so that the curtain 2 can be unrolled and unrolled. The holding magnet 51 is controlled so that it is switched off when an emergency signal and the rocker arm 43 to the curtain 2 tilts, the roll-off 41 thus activated. The same applies if the holding magnet 51 is de-energized by a power failure and loses its holding power.

In a further embodiment, in addition, a biasing element on the roll-off 41 be provided, which is the rocker arm 43 in addition to gravity in the direction of the blocking position presses when the holding magnet 51 is de-energized. The holding magnet 51 must then be adjusted so that in the energized state, both the weight and the force applied by the biasing force on the tilting element 41 ' compensates and the rocker arm 43 holding in the open position. The biasing element may, for. B. one on the tilt shaft 47 mounted coil spring, which on the one hand on one of the support webs 48 . 49 and on the other hand on one of the retaining legs 45 . 46 or the connecting bridge 44 is attached.

Is the curtain 2 not yet rolled up, so the rocker slides 43 while rolling up the curtain 2 along until it has reached the upper position. This applies both in the event that an emergency opening of the blind 2 in case of power failure via the spring shaft 11 done or the hanging 2 if there is a power supply, the engine is emergency opened.

To the roll-off protection 41 To be able to build as compact as possible are in the 6 to 8th shown training of the rocker arm 43 and the holding magnet 50 arranged laterally to each other, so that the roll-off 41 is very flat.

To go directly to the darkening device 1 to be able to show that the roll-off protection 41 is activated, the retaining legs 45 . 46 of the tilted tilting element 41 ' not shown slots in a cover 52 the roll-off protection 41 protrude.

Also, several roll-off devices 41 be provided, for example on each guide rail 4 . 5 a.

Next, the invention provides a in 6 and 8th shown, formed by a gas spring known per se stop damper 53 with a stop buffer 54 before, on the fast rolling up of the curtain with the spring shaft 11 the curtain rail 3 strikes and brakes gently.

An in 9 shown dimming system according to the invention 55 has a Verdunldungsvorrichtung invention described above 1 on. In addition, on the guide rail 2 position sensors 56 and 57 arranged to determine if the hangings 2 in an upper open position (position sensor 56 ) or in a lower closed position (position sensor 57 ). Next there are the spring breakage sensor described above 23 and roll-off protection 41 intended. All these sensors 23 . 41 56 and 57 and a clutch control 58 for the electromagnetic clutch 14 , the winding motor 8th , an emergency button 59 and a handset 60 are not individually designated connecting lines with a controller 61 of the blackout system 55 connected.

With the handset 60 In normal operation, the curtain is 2 opened and closed.

In an emergency (without power failure) the curtain 2 automatically opens the emergency button 59 pressed, next to the controller 61 additionally directly with the clutch control 58 connected is. Will the emergency button 59 pressed, then the clutch control 58 directly de-energized, so that the Electromagnetic clutch 14 opened and therefore the blind 2 automatically rolled up.

Particularly advantageous effect of the spring breakage sensor 23 and the roll-off protection 41 at a decrease in the spring force of the return spring 10 together, be it an abrupt break of the return spring 10 or a gradual, especially age-related decrease in the spring force of the return spring 10 ,

Detects the spring pressure sensor 23 namely an excessive drop in the spring force of the return spring 10 , it sends a corresponding signal to the controller 61 , which then the curtain 2 automatically via the engine 8th starts up and the roll-off protection 43 activated. Here, the roll-off can 41 advantageous already during startup by currentless switching of the holding magnet 51 be activated because the rocker arm 41 at not quite raised curtain 2 as described above on the curtain 2 along slides. Is the curtain 2 then driven all the way up and rolled up, the rocker arm falls 41 down against the stop bar 50 and thus safely blocks the unrolling plane A of the curtain 2 ,

Next may be in response of the spring break sensor 23 and thus automated start-up of the blind 2 in through the roll-off 41 secured against rolling secured upper position an information signal to the controller 61 be issued or transmitted to a remote control center, for a speedy review of the return spring 10 perform.

Represents the upper position sensor 56 then realize that the hangings 2 At the top, he can advantageously send a signal to the controller 61 spend, which indicates the roll-off 41 activated, the rocker arm 43 So in the in 8th shown blocking position falls.

LIST OF REFERENCE NUMBERS

1

darkening system

2

curtain

3

Behangschiene

4

left guide rail

5

right guide rail

6

Behangwelle

7

clutch

8th

winding motor

9

supporting frame

10

return spring

11

spring shaft

12

Stub shaft spring shaft

13

Spring shaft bearings

14

Electromagnetic clutch

15

electromagnet

16

supply line

17

Coupling counterpart

18

engine mount

18 '

driver screw

19

motor shaft

20

Belleville spring

21

Coupling flanks electromagnet

22

Coupling flanks on the motor side

23

Spring break sensor

24

bearings

25

hollow cylindrical expansion

26

right thigh

27

left thigh

28

Thigh gap

29

blocking leg

30

measuring jaw

31

microswitch

32

selector

33

button

34

stop surface

35

Adjusting spring blocking leg

36

Adjusting spring measuring leg

37

Adjustment screw locking leg

38

Adjusting screw measuring leg

39

Threaded hole blocking legs

40

Threaded measuring legs

41

roll-off

41 '

Kippelelement

42

tilt axis

43

rocker arm

44

connecting web

45

holding leg

46

holding leg

47

tilting shaft

48

holding web

49

holding web

50

stop web

51

holding magnet

52

Cover roll-off protection

53

stop damper

54

buffer

55

darkening system

56

Position sensor "curtain up"

57

Position sensor "blind down"

58

clutch control

59

emergency button

60

handset

61

control

A

rolling plane

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19918489 C2 [0002, 0030]
• DE 3132073 A1 [0003]
• DE 102004029553 A1 [0004]

Claims (19)

Verdunldungsvorrichtung ( 1 ) for covering an opening with a curtain ( 2 ), which can be wound up and unwound at one by means of a winding motor ( 8th ) rotatable hanging shaft ( 6 ) mounted on one side via a spring shaft ( 11 ) with a when unwinding the Behangs ( 2 ) exciting return spring ( 10 ) rotatably mounted on a stationary support frame ( 9 ) is mounted and on its axially opposite side via a coupling ( 7 ) with a motor shaft ( 19 ) of the rotationally fixed to the support frame ( 9 ) arranged winding motor ( 8th ) is connectable, characterized in that a spring breakage sensor ( 23 ) for monitoring the state of the return spring ( 10 ) is provided and / or a roll-off ( 41 ) is provided and / or the clutch ( 7 ) as electromagnetic clutch ( 14 ) is trained. Verdunldungsvorrichtung ( 1 ) according to claim 1, characterized in that the electromagnetic clutch ( 14 ) an electromagnet ( 15 ) and through this electromagnetically in the axial direction of the Behangwelle ( 6 ) movable coupling counterpart ( 17 ) having. Darkening device ( 1 ) according to claim 2, characterized in that for releasing and closing the electromagnetic clutch ( 14 ) the coupling counterpart ( 17 ) in the axial direction relative to the winding motor ( 8th ) and for torque transmission between coupling counterpart ( 17 ) and winding motor ( 8th ) in the radial direction with the motor shaft ( 19 ) of the winding motor ( 8th ) connected is. Darkening device ( 1 ) according to claim 3, characterized in that between coupling counterpart ( 17 ) and an engine mount ( 18 ) a return element, in particular a plate spring ( 20 ) is provided for releasing the electromagnetic clutch ( 14 ) with electroless electromagnet ( 15 ) the coupling counterpart ( 17 ) from the electromagnet ( 15 ) moved away. Darkening device ( 1 ) according to one of claims 2 to 4, characterized in that mutually facing coupling edges ( 21 . 22 ) of electromagnet ( 15 ) and coupling counterpart ( 17 ) with coupled electromagnetic clutch ( 14 ) cooperating form-fitting elements for forming a positive connection between the electromagnet ( 15 ) and coupling counterpart ( 17 ) exhibit. Darkening device ( 1 ) according to one of claims 2 to 5, characterized in that the electromagnet ( 14 ) for supplying electrical energy with a through a stub shaft ( 12 ) of the spring shaft ( 11 ) to the outside supply line ( 16 ) connected is. Darkening device ( 1 ) according to one of the preceding claims, characterized in that the spring breakage sensor ( 23 ) one opposite the Behangwelle ( 6 ) fixed spring shaft bearing ( 13 ) with a sliding bearing ( 24 ) for rotatably supporting a stub shaft ( 12 ) of the spring shaft ( 11 ), wherein a blocking device ( 29 . 30 ) a complete revolution of the spring shaft ( 11 ), and the stub shaft ( 12 ) an actuating element ( 30 ) for actuating an electrical switch ( 31 . 32 ) having. Verdunldungsvorrichtung ( 1 ) according to claim 7, characterized in that the blocking device at least one of the stub shaft ( 12 ) projecting into one between two legs ( 26 . 27 ) of the spring shaft bearing ( 13 ) has engaging blocking legs. Darkening device ( 1 ) according to claim 7 or 8, characterized in that the actuating element has a protruding from the stub shaft measuring leg, the wound in wound ( 2 ) permanently actuates the electrical switch when the spring force of the return spring ( 10 ) of the spring shaft ( 13 ) does not fall below a predetermined lower limit. Darkening device ( 1 ) according to claim 9, characterized in that in the spring shaft bearing ( 13 ) at least one in a plane of rotation of the measuring leg ( 30 ) provided bore ( 40 ) with a rotatable adjusting screw ( 38 ) provided with the measuring leg ( 30 ) via a setting spring ( 36 ), wherein the adjusting spring ( 36 ) one of the spring force of the spring shaft ( 11 ) counteracting force on the measuring leg ( 30 ) exercises. Darkening device ( 1 ) according to claim 10, characterized in that in the spring shaft bearing ( 13 ) another in the plane of rotation of the measuring leg ( 30 ) provided bore ( 39 ) with a rotatable further adjusting screw ( 37 ) provided with the measuring leg ( 30 ) via another adjusting spring ( 35 ), wherein the further adjusting spring ( 35 ) one of the spring force of the spring shaft ( 11 ) equivalent force on the measuring leg ( 30 ) exercises. Darkening device ( 1 ) according to one of the preceding claims, characterized in that the roll-off protection ( 41 ) one opposite a rolling plane (A) of the curtain ( 2 ) about a substantially parallel to the rolling plane (A) extending tilting axis ( 41 ) rotatable tilting element ( 41 ' ) with a rocker arm ( 43 ), which via an energized electromagnetic holding magnet ( 51 ) is held in an unstable position outside the rolling plane (A) and due to gravity in a Blocking position in the rolling plane (A) falls when the holding magnet ( 51 ) is de-energized. Darkening device ( 1 ) according to claim 12, characterized in that the center of gravity of the tilting element ( 41 ' ) in the unstable position between the tilt axis ( 42 ) and the rolling plane (A) is located. Darkening device ( 1 ) according to claim 13, characterized in that the center of gravity of the rocker arm ( 43 ) in the unstable position above the tilting axis ( 42 ) lies. Verdunldungsvorrichtung ( 1 ) according to any one of claims 12 to 14, characterized in that a fixed to the Verdunldungsvorrichtung ( 1 ) attached stop bar ( 50 ) the rocker arm ( 43 ) stops from below in the blocking position. Dimming system ( 55 ) with a Verdunldungsvorrichtung ( 1 ) according to one of the preceding claims, guide rails ( 4 . 5 ) for guiding the blind ( 2 ) between an upper and lower position of the curtain ( 2 ) and a controller ( 61 ) of the darkening system ( 55 ). Dimming system ( 55 ) according to claim 16, characterized in that a position sensor ( 56 . 57 ) for the detection of the blind ( 2 ) is provided in the upper, open position and / or in the lower, closed position. Method for operating a dimming system ( 55 ) according to claim 16 or 17 with a spring breakage sensor ( 23 ) and at least one roll-off safety device ( 41 ), characterized in that when the spring break sensor ( 23 ) the curtain ( 2 ) is moved to the upper position. A method according to claim 18, characterized in that when the spring break sensor ( 23 ) the roll-off safety device ( 41 ) is activated.

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