GB2497104A - A device for terminating the rotary movement of a driven roller blind shaft - Google Patents

Abstract

A device 1 is provided for terminating rotary movement of a driven shaft, for example on a roller blind. The device comprises a switch-controlling member controlling a switch 37, 38 to terminate the rotation of the shaft, a first rotation limiting arrangement 4 comprising first and second toothed wheels that are rotated by the shaft and a first toothed wheel being rotated by the driven shaft. Rotation of the first toothed wheel causes rotation of a second toothed wheel. The second toothed wheel and switch-controlling member are each provided with a pair of formations for controlling operation of the switch. Engagement of the formations causes said switch-controlling member to operate said switch and terminate rotation of the shaft. Also claimed is a device with primary and secondary sets of geared wheels that are biased into an engaged position and a disengagement mechanism to disengage the two sets of wheels and gears.

Description

Automatic stop device for motor for door, shutter or the like The present invention relates to an automatic stop device for a motor for driving a door, shutter or the like, and a motor assembly comprising such a stop device and a motor.

It is important to limit the movement of motors which drive a door, shutter, blind, curtain or the like so that neither the motor nor the item being driven is damaged. It is known to limit the upper and lower limits of motion. This has been achieved in the past by providing switches on the item being driven. It is also known to provide a device for stopping rotation of the motor comprising one or two stopping mechanisms for limiting the movement of the motor. Each stopping mechanism typically comprises a counting arrangement comprising a plurality of wheels. Each wheel is provided with a notch. Associated with each notch is a finger provided on a switching arm. When all of the notches are aligned, all of the fingers can enter the notches, thereby permitting movement of the switching arm. Movement of the switching arm causes operation of the motor to be interrupted. In US5374791, each of a plurality of gears having a different number of teeth is driven directly by a gear mcunted on a drive shaft. Whilst such an arrangement may be used to set both the upper and lower limits of travel, the accuracy of such an arrangement is limited. In US441l438, the drive shaft drives one gear directly, rotation of that gear causing other, linked gears in a gear train to rotate. The arrangement of a plurality of gears, each with a notch for the receipt of a corresponding finger may be difficult, since it is necessary to calculate the position of each notch in order for the device to operate.

The device of the present invention seeks to ameliorate one or more of the problems mentioned above.

In accordance with a first aspect of the present invention, there is provided a device for terminating rotary movement of a driven shaft, the device comprising a switch-controlling member operable to control a switch to terminate the rotary movement of the driven shaft, a first rotation limiting arrangement comprising a plurality of toothed wheels operable to be rotated by rotation of driven shaft, a first toothed wheel operable to be rotated by driven shaft, the first toothed wheel being coupled to a second toothed wheel (optionally via one or more further toothed wheels) such that rotation of the first toothed wheelL causes rotation of the second toothed wheel; said device being provided with a pair of formations for controlling operation of the switch, the second toothed wheel and switch-controlling member each being provided with one of said pair of formations, engagement of the formation provided on the second toothed wheel with the corresponding formation provided on the switch-controlling member causing said switch-controlling member to engage or disengage said switch and thereby terminate the rotation of the driven shaft, wherein the first rotation limiting arrangement comprises only one of such pairs of formations for controlling operation of a switch.

The device of the first aspect of the present invention has proved to be surprisingly effective, given its simplicity in

relation to the prior art.

Those skilled in the art will realise that the motor is not part of the device of the present invention. Those skilled in the art will also realise that the switch is not necessarily part of the device of the present invention, although the device may optionally comprise a switch.

The first rotation limiting arrangement would typically be operable to limit motion of shaft when further motion of said shaft may cause damage to the motor or to the object which is being moved by said motor. For example, the first rotation limiting arrangement may be operable to stop the rotation of the motor when a shutter is in one of a top or bottom position. For example, the device may help prevent a motor from winding in a shutter past a top position, where further winding of the shutter may cause damage to the shutter.

Likewise, the first rotation limiting arrangement may be operable to inhibit the motor from winding the shutter past a certain bottom position.

The device may comprise a set of primary wheels mounted for rotation about a first axis. The device may comprise a set of secondary gears mounted for rotation about a second axis. The first and second toothed wheels mentioned above typically form part of the set of primary wheels. The device may comprise a disengagement mechanism operable to move said primary wheels and secondary wheels relative to one another between a first, engaged position and a second, disengaged position. In the engaged position, certain of the primary wheels will be meshed with certain of the secondary wheels. Typically, the secondary wheels and primary wheels are biased into the first, engaged position. Optionally, the secondary gears are biased into engagement with the primary gears. The disengagement mechanism may be operable to move the secondary wheels from the first, engaged position to the second, disengaged position.

Optionally, operation of the disengagement mechanism may be associated with inhibition of operation of the switch to terminate the rotation of the shaft. For example, the disengagement mechanism may be provided with a disengagement member movable between a first position in which the primary and secondary wheels are in engagement to a second position in which the primary and secondary wheels are disengaged. The disengagement member may be pivotaily movable between the first and second disengagement member positions. Optionally, the disengagement member is movable so that movement from the first disengagement member position to the second disengagement member position causes reiative movement of the primary and secondary sets of gears to the disengaged position, optionaily by moving the set of secondary gears.

When the disengagement member is in the second disengagement member position, operation of the switch to terminate rotation of the shaft may be inhibited. For exampie, when the disengagement member is in the second disengagement position, the disengagement member may inhibit movement of the switch-controlling member, thereby inhibiting operation of the switch which would otherwise terminate rotation of the shaft.

The device may comprise a pivotally mounted arm for controlling the disengagement member. In use, pivoting of the arm may cause the disengagement member to move between the first and second disengagement member positions. For example, the disengagement member may be associated with a first end of the arm so that movement of said first end of the arm causes movement of the disengagement member between the first and second disengagement member positions. For example, movement of the first end of the arm upwards may pivot the disengagement member from the first to the second disengagement member position.

Optionally, the disengagement mechanism may be provided with a user-operable disengagement selector (such as a push button) operable to control disengagement and engagement of the primary and secondary wheels. The disengagement mechanism may optionally be retained in the disengaged position without an external force being applied by a user. For example, the disengagement mechanism may be latched in the disengaged position, and may only be moved back to the engaged position by the actions of the user. In other words, the disengagement mechanism is "bistable". For exampie, the disengagement selector may comprise a push button operable to operate the disengagement mechanism between the engaged and disengaged states, Pushing the push button causes the disengagement mechanism to change state, whatever the initial state of the disengagement mechanism. It is preferred that when the disengagement mechanism is in a disengaged state, the button is in a lowered position, and when the primary and secondary wheels are engaged, the push button is in a raised position.

A device which is iatched or otherwise stable in the disengaged state may optionally be provided by first and second control surfaces, spaced relative to one another and being movable relative to one another. The first and second control surfaces are typically shaped so that relative movement of the first and second control surfaces oontrols whether the disengagement meohanism is in the disengaged or engaged state. One of the first and second control surfaces may be associated with the disengagement selector, movement of the disengagement selector causing movement of the first control surface. Movement of the disengagement selector may be translational movement (optionally substantially straight-line translational movement) . The first control surface may comprise a stepped surface. The second control surface may comprise one or more steps. If the device comprises an arm for moving a disengagement member, the position of the arm may be operable by the first and second control surfaces.

The set of primary wheels may optionally comprise one or more intermediate toothed wheels between the first and second toothed wheels. There may optionally be from 1 to 4 intermediate toothed wheels. One or more (typically each) of the intermediate toothed wheels may typically be provided with a plurality of teeth on one face of said wheel and fewer teeth (typically one, two or three, for example) on the other face of said wheel. For one rotation of a particular wheel as driven by the plurality of teeth on one face, there is very little driving of adjacent wheels performed by the face provided with fewer teeth because there are fewer teeth to drive rotation of an adjacent wheel. When the primary and second sets of wheels are in the engaged state, a secondary wheel is typically provided between an adjacent pair of primary wheels. The secondary wheel is typically arranged to be engaged by teeth on one face of one primary wheel and arranged to engage the teeth on the other face of the other primary wheel. For example, a secondary wheel is typically arranged to be engaged by the teeth (typically 1, 2 or 3 in number) on one side of a first wheel. Therefore, one rotation of this first wheel will cause 1, 2 or 3 teeth on that first wheel to engage with the teeth of the secondary wheel. That secondary wheel engages with the plurality of teeth on a second primary wheel so that rotation of the secondary wheel is transmitted to the second primary wheel. In this manner, large angular rotation of the first primary wheel causes a far smaller angular rotation of the second primary wheel. In such a way, a gear chain can be generated.

The pair of formations provided on the second wheel and the switch controlling member may be independently selected from a male and female formation. Typically, at least one of the pair of formations is a male formation. Typically, one of the pair of formations is a male formation and the other of the pair of formations is a female formation. Typically, the formation provided on the second toothed wheel is a female formation, for example in the form of a notch. Typically, the formation provided on the switch controlling member is a male formation, such as a finger for placement into said notch. In operation, placement of a male formation into a female formation is associated with movement of part of the switch controlling member so that the switch is operated to prevent rotation of the shaft. Optionally, engagement of the pair of formations may inhibit rotation of the second wheel in one direction.

This may be achieved, for example, by providing a notch having a shallow sloping surface and a steep sloping surface, the steep sloping surface inhibiting further movement of the second toothed wheel in one direction. The shallow sloping surface does not significantly inhibit movement of the second toothed wheel in the other rotational direction.

The device may optionally comprise a second rotation limiting arrangement. If the first rotation limiting arrangement is used to set the upper limit of motion of a shutter or the like, then the second rotation limiting arrangement is used to set the lower limit of motion of the shutter or the like. The second rotation limiting arrangement may comprise those features described above in relation to the first rotation limiting arrangement. The second rotation limited arrangement may be provided with a disengagement mechanism as described above in relation to the first rotation limiting arrangement.

The device, for example, may also be provided with a pivotally mounted arm for controlling the disengagement member associated with the second rotation limiting arrangement.

The device may be provided with a means operable to rotate the shaft in the event of motor failure. Motor failure may result from failure of the motor itself or failure of the power supply to the motor. The means operable to rotate the shaft in the event of motor failure may be operably linked to said first rotation limiting arrangement (and optionally to the second rotation limiting arrangement) such that operation of said means causes operation of the first rotation limiting arrangement (and second rotation limiting arrangement, if present) . In this way, the winding limits imposed by the first and optionally the second rotation limiting arrangements during normal use of shutter are imposed when the shutter is raised or towered manually. Said means may comprise a manually-operable screw, the screw typically being in meshing engagement with a manual-operation gear. The manual-operation gear is operable to rotate the shaft, thereby raising or lowering the shutter or the like associated with the shaft.

This may be achieved for example, by providing the device with a rotatable collar which is operably linked to the manual-operation gear, the collar engaging said shaft or being otherwise operably connected to said shaft so that rotation of the collar causes rotation of said shaft.

En aocordance with a second aspeot of the present invention, there is provided a device for terminating rotary movement of a driven shaft, the device comprising a switch-controlling member operable to control a switch to terminate the rotary movement of the driven shaft, a first rotation limiting arrangement operable to control the operation of the switch controlling member, the first rotation limiting arrangement comprising a first set of toothed wheels and a second set of toothed wheels, and a disengagement mechanism operable for controlling relative movement of the first and second sets of wheels between an engaged state in which wheels of the first set are engaged with wheels of the second set and a disengaged state in which the wheels of the second set are disengaged from the wheels of the first set, the disengagement mechanism being retained in the disengaged position in the absence of an external force being applied by a user.

The disengagement mechanism may comprise a user-operable disengagement selector for controlling the operation of the disengagement mechanism When the disengagement mechanism is in a disengaged state, the disengagement selector is optionally in a lowered position, and when the primary and secondary wheels are engaged, the disengagement selector is optionally in a raised position.

The device may comprise first and second control surfaces, spaced relative to one another and being movable relative to one another. The first and second control surfaces are typically shaped so that relative movement of the first and second control surfaces controls whether the disengagement mechanism is in the disengaged or engaged state. One of the first and second control surfaces may be associated with the disengagement selector, movement of the disengagement selector causing movement of the first control surface. Movement of the disengagement selector may be translational movement (optionally substantially straight-line translational movement) . The first control surface may comprise a stepped surface. The second control surface may comprise one or more steps. If the device comprises an arm for moving a disengagement member, the position of the arm may be operable by the first and second control surfaces.

The device may comprise a plurality of toothed wheels operable to be rotated by rotation of driven shaft, a first toothed wheel operable to be rotated by driven shaft, the first toothed wheel being coupled to a second toothed wheel (optionally via one or more further toothed wheels) such that rotation of the first toothed wheel causes rotation of the second toothed wheel; said device being provided with a pair of formations for controlling operation of the switch, the second toothed wheel and switch-controlling member each being provided with one of said pair of formations, engagement of the formation provided on the second toothed wheel with the corresponding formation provided on the switch-controlling member causing said switch-controlling member to engage or disengage said switch and thereby terminate the rotation of the driven shaft.

Optionally, the device may comprise only one of such pairs of formations for controiling operation of a switch.

The device of the second aspect of the present invention may comprise those features described above in relation to the second aspect of the present invention. For example, the device may comprise a second rotation limiting arrangement, together with a disengagement mechanism.

In accordance with a third aspect of the present invention there is provided a motor assembly for driving a door, shutter or the like, said motor assembly comprising a motor for driving a door, shutter or the like and a device in accordance with the first or second aspect of the present invention for controlling the operation of said motor.

The stop device of the present invention will now be described by way of example only with reference to the following figures of which: Figure 1 is a perspective view from above of an example of an embodiment of a device in accordance with the first and second aspect of the present invention; Figure 2 is a perspective view of part of the device of Figure 1 showing one of the rotation limiting arrangements in detail; Figure 3 is a view of the end of the device of Figure 1, an end component having been removed to show certain internal components of the device; and Figure 4 is a view of the end component which was removed from the device.

An example of a device in accordance with the first and second aspects of the present invention will now be described initially with reference to Figures 1, 2 and 3. The device is denoted generally by reference numeral 1, and is generally elongate in shape. The device 1 is generally used to control the operation of a motor (not shown) . The motor is typically attaohed to the devioe at end 9 of the device. As is well-known to those skilled in the art, the motor causes the rotation of a tubular member or sleeve (not shown) which, in turn, causes a shutter or the like (not shown) to be raised or lowered, dependent on the direction of rotation of the tubular member or sleeve. The rotation of the tubular member or sleeve causes the rotation of oollar 3, which, in turn, operates two rotation limiting arrangements 4, 5 which control the operation of the motor and limit the travel of shutter whioh is being driven by the motor. One of the rotation limiting arrangements 4, 5 limits the upper limit of travel of the shutter and the other of the rotation limiting arrangements limits the lower limit of travel of the shutter. A more detailed description of the device 1 will now be given.

Actuation of the motor causes rotation of collar 3 as mentioned above. Referring now to Figure 4, Figure 4 shows an end-on view of the device 1 with the end piece 13 having been removed from the device 1. Gear 12 as shown in Figure 4 is coupled to collar 3 so that rotation of the collar 3 causes rotation of gear 12. Referring now to Figure 5 which shows end piece 13, rotation of gear 12 (see Figure 4) causes rotation of gear 14 which is turn causes rotation of gear 15 (gears 14, 15 being coupled together) . Referring once again to Figure 4, gear 15 (Figure 5) protrudes through aperture 16 and meshes with a gear (not shown) which is associated with shaft 11.

Rotation of gear 15 therefore causes rotation of shaft 11.

Shaft 11 is provided with gears which mesh with (and drive) gears provided as part of rotation limiting arrangements 4, 5, and these will be described in more detail with reference to rotation limiting arrangement 4. shaft 11 is provided with gears 17, 19. These gears mesh with gears 19, 20 respectively in counting mechanism 4 and therefore rotation of shaft 11 causes rotation of gears 19, 20 of rotation limiting arrangement 4. Rotation limiting arrangement 4 comprises two sets of gears, a set of larger primary gears denoted generally by reference numeral 21 and a set of smaller secondary gears denoted generally by reference numeral 22. The primary gears 21 are rotatably mounted on an axle 23. Secondary gears 22 are rotatably mounted on an axel 24. During normal operation, secondary gears 22 are urged intc meshing engagement with associated primary gears 21 by torsion spring 25. Axle 24 and secondary gears 22 are mounted in a carrier 26. The carrier 26 is pivotally mounted towards the bottom of the carrier to cradle 27, the torsion spring 25 being arranged to urge the carrier 26 into its normal operating position, with the seoondary gears 22 in meshing engagement with the primary gears 21. As will be described below, it is possible to pivot the carrier 26 out of its normal operating position, against the biasing effect of the spring. Primary gears 21 comprise gears 20, 28, 29, 30, 31. Each of the primary gears is provided with teeth (not labelled) on one side (the right side in Figure 3) . Secondary gears 22 comprise gears 32, 33, 34, 35. Referring to Figure 3, the secondary gears are provided with teeth (not labelled) on both the left and right hand side of the gears. Operation of the rotation limiting arrangement will now be described in detail. Gear 32 is urged into engagement with gears 20 and 28, so that rotation of gear 20 as caused by actuation of the motor causes rotation of gear 32, which, in turn, causes rotation of gear 28. Referring to Figure 3, the left hand side of gear 28 is provided with a single tooth (not shown) which, on rotation of gear 28, comes into meshing engagement with gear 33, but only once per rotation of gear 28. Gear 29 is in meshing engagement with the left hand part of gear 33 so that rotation of gear 33 causes rotation of gear 29. However, because the left hand side of gear 28 is only provided with a single tooth, gear 33 is only rotated a small amount for each rotation of gear 28.

Therefore, gear 29 is only rotated small amount (is this case, about 36 degrees) for each rotation of gear 28, gear 29 rotating once for every ten rotations of gear 28.

Likewise, the left hand side of gear 29 is provided with a single tooth (not shown) which, on rotation of gear 29, comes into meshing engagement with gear 34, but only once per rotation of gear 29. Gear 30 is in meshing engagement with the left hand part of gear 34 so that rotation of gear 34 causes rotation of gear 30. However, because the left hand side of gear 29 is only provided with a single tooth, gear 34 is only rotated a small amount for each rotation of gear 29.

Therefore, gear 30 is only rotated by a small amount (is this case, about 36 degrees) for each rotation of gear 29, gear 30 rotating once for every ten rotations of gear 29. Using such a gear chain, one rotation of gear 30 is associated with 100 rotations of gear 20.

Likewise, the left hand side of gear 30 is provided with a single tooth (not shown) which, on rotation of gear 30, comes into meshing engagement with gear 35, but only once per rotation of gear 30. Gear 31 is in meshing engagement with the left hand part of gear 35 so that rotation of gear 35 causes rotation of gear 31. However, because the left hand side of gear 30 is only provided with a single tooth, gear 35 is only rotated a small amount for each rotation of gear 30.

Therefore, gear 31 is only rotated by a small amount (is this case, about 36 degrees) for each rotation of gear 30, gear 31 rotating once for every ten rotations of gear 30. Using such a gear chain, one rotation of gear 31 is associated with 1000 rotations of gear 20.

It is therefore apparent that the gear chain provided by the primary and secondary gears provides a method of counting the number of rotations generated by the motor.

The way in which the rotaticn limiting arrangement 4 is operabie to controi the operation of the motor will now be described. The device 1 comprises two switches 37, 38, each of which is associated with a rotation iimiting arrangement 4, 5.

The switches 37, 38 are electrically connected to the motor so that, in a first switch state, electricity is provided to the motor so that the motor can be rotated either way, but should either switch enter a second switch state, rotation of the motor in a particular direction is not possible. Each switch 37, 38 is associated with a respective switch actuator 39, 40.

In a normal operating condition, switch engaging parts 41, 42 of switch actuators 39, 40 are in contact with the respective switches 37, 38, and hold the switches in a first switch state. If both switches are in this first state, the motor can be operated to rotate the sleeve/tubular member (not shown) in both directions. Each switch actuator 39, 40 is provided with a finger (one of which is shown in Figure 3, 43) which extends from a switch actuator arm 44, 45. P. spring (not shown) urges the finger 43 into engagement with the surface of gear 31.

Gear 31 is provided with a notch 36. It is the only gear of the primary gears 21 to be provided with such a notch.

Operation of the motor causes gear 31 to rotate, thus causing movement of the notch 36 relative to finger 43. When the notch is aligned with finger 43, the finger 43 is urged into the notch. This movement of the finger into the notch 36 causes a movement of the switch engaging part 41 away from the switch 37, thus relieving pressure on the switch 37, allowing the switch to enter the second switch state. In this state, the motor can only operate to turn the sleeve/tubular member in one direction. The counting mechanism therefore prevents further turning of the sleeve/tubular member in a given direction, and therefore prevents further movement (typically up or down) of the shutter. The rotation limiting arrangement therefore provides a lower or upper limit to the movement of the shutter.

The above description is given in relation to rotation limiting arrangement 4 in which rotation limiting arrangement 4 is used to provide an upper or lower limit to the movement of the shutter. Likewise, rotation limiting arrangement 5 is arranged in an analogous manner to limit the upper or lower limit of movement of the shutter which is not provided by rotation limiting arrangement 4.

The setting of the rotation limiting arrangements 4, 5 to set the limits of motion of the shutter will now be discussed.

Each of the rotation limiting arrangements 4, 5 is initially provided in a "stop" position i.e. with the finger 43 engaged in notch 36. As mentioned above, this naturally results in the switch 41 being in a second switch state, preventing the shutter being moved in one particular direction. This is over-ridden during the setting of the rotation limiting arrangement 4 as will now be discussed. As mentioned above, during normal operation of the device 1, primary and secondary gears 21, 22 engage together to form a gear chain. During the setting of the limits, the secondary gears 22 are moved out of meshing contact with the primary gears as will now be described so that actuation of the motor does not causes movement of the gear 3L which is provided with the stopping notch 36. Device 1 is provided with a disengagement mechanism comprising a push button 7. Push button 7 is linked to one end of a rod 50 SO that pushing on push button 7 exerts a downwards force on the end 50a of rod 50. The other end of rod 50 is placed in contact with and underneath the arm 51 of disengagement member 52. Rod 50 is pivotally mounted so that pushing end SOa of rod in a generally downwards direction causes the rod to pivot about a pivot point (not shown), and causes the other end SOb of rod 50 to move upwards. This upwards movement of the end SOb causes disengagement member 52 to move pivotally about axis 53 against the biasing force provided by torsion spring 54. Disengagement member 52 is provided with a slot (not shown) for the receipt of the axle 24 of carrier 26. On movement of the disengagement member 52, the axle 24 is received in the slct, movement of the disengagement member 52 causing pivotal movement of the carrier 26, and thereby disengaging the seccndary gears 22 from the primary gears. As mentioned above, the finger 43 is engaged in notch 36. This would, in normal operation, permit the switch engaging part 41 to move out of contact with the switch, thereby preventing movement of the shutter in one particular direction. This is not desirable when trying to set the limit of motion of the shutter, because one wishes to permit the shutter to travel in that particular direction when setting the limit. Therefore, the disengagement member 52 is further provided with a finger (not shown) which, when the disengagement member 52 is rotated so that the secondary and primary gears are disengaged, either engages with, or inhibits the motion of, the switch actuator 39, so that the switch engaging part 41 cannot move sufficiently far away from the switch so as to change the state of the switch. Therefore, the switch is overridden by the disengagement member 52 to enable motor operation. The pivoting movement of carrier 16 causes fingers (not shown) associated with each of the secondary gears to engage in cams (not shown) associated with each of gears 28, 29, 30, 31 to "lock" these gears in position so that they do not move. When the counting mechanism is in this disengaged stated, the user operates the motor to move the shutter to the desired upper or lower limit. Operation of the motor causes shaft 11 and gears 17, 18, 19, 20 to rotate, but none of the other primary or secondary gears rotate because of the disengagement of the primary and secondary gears. Therefore, finger 43 remains opposite notch 36. Once the shutter is at the desired upper or lower limit, rod 50 is actuated using button 7 to lower end SOb of rod 50, thereby permitting secondary gears 22 to engage with primary gears 21. The reengagement of the primary and secondary gears is associated with movement of the finger 43 into notch 36, which is associated with movement of the switch engagement part 41 away from the switch, thereby preventing operation of the motor to generate movement in one rotational direotion.

Rotation limiting arrangement 5 is used to set the upper or lower limit of motion of the shutter in a method analogous to that described above in relation rotation limiting arrangement 4.

The operation of the push button 7 and disengagement mechanism will now be described. When the device is in a normal operating configuration and the primary and second gears are engaged, push buttons 7, 8 are in a raised position. In this state, the end 50a of rod 50 is located in upper part 60a of slot 60. In order to disengage the secondary and primary gears, button 7 is pressed, causing end 50a to move downwards in slot 60 to the bottom 60b to return to the position shown in Figure 4. In this position, the secondary gears have been disengaged from the primary gears so that setting of the travel limit of the shutter can take place as described above.

Once the limit is set, pressing the button 7 causes rod end 50a to move into position 6Gb and then back to position 60a, in which position the primary and secondary gears are engaged.

The device 1 is also provided with a manual override mechanism which will now be briefly described with reference to Figs. 1 to 4. Device 1 is provided with a screw 70 located in a recess 71. The screw 70 is accessible via aperture 10 best seen in Fig. 1, the end of the screw being provided with a configuration for the receipt of a tool for rotating the screw. Rotation of screw 70 causes rotation of gear 72. Gear 72 is coupled to gear 12 so that rotation of gear 72 causes rotation of gear 12. Rotation of gear 12 causes rotation of the collar 3, which in turn causes rotation of the sleeve/tubular member associated with the collar 3, thereby raising or lowering the shutter, dependent on the direction of rotation of the screw 70. Operation of the manual override mechanism also operates the counting mechanisms 4, 5 so that it is not possible to manually move the shutter past the lower and upper limits of travel associated with the counting mechanisms 4, 5 as will now be described. As mentioned above, rotation of screw 70 causes rotation of gear 12. This, in turn, causes rotation of gears 14, 15 which cause rotation of shaft Il and rotation of the gears on the counting mechanisms 4, 5. On reaching the upper or lower limit of travel as set for the respective counting mechanism, the finger 43 has entered notch 36. The notch is so shaped that the engagement of the finger and notch physically resist further relative movement in one direction of the gear 31 carrying the notch 36 relative to finger 43.

The device of the figures above has been described for the control of the deployment of a shutter. Those skilled in the art will realise that the device of the present invention may be used to control the deployment of other things, such as roller blinds.

The device of the figures above has been described as having two counting mechanisms, both of which have only one wheel which is provided with a configuration for engaging with a corresponding configuration on a switch-engaging member. One of the two counting mechanisms may comprise more than one wheel having a configuration for engaging with corresponding configurations on the switch-engaging member.

Those skilled in the art will realise that the device of the present invention may have a different mechanism for disengaging the counting mechanism so that the upper and/or lower travel limits can be set.

The example above describes a device which sets both upper and lower limits for the movement of a shutter. Those skilled in the art will realise that it is possible for the device of the present invention may only have one counting mechanism, thereby setting only an upper or lower limit.

The example above describes a device with a manual over-ride which allows a user to manually raise and/or lower the shutter in the event of motor failure (e.g. in the event of power failure) . Those skilled in the art will realise that the manual over-ride feature is not an essential part of the present invention. Furthermore, those skilled in the art will realise that other manual over-ride mechanisms may be used.

Where, in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable eguivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.