Technology field

The present invention relates to a door operator system for opening and closing an opening, and a corresponding method.

Background

A door operator system for a sectional door typically comprises a door connected to a door frame and a drive unit arranged to move the door along the door frame between an open and closed position for opening and closing the opening. A sectional door are typically used as garage doors or as an industrial door. The drive unit could comprise a motor or a mechanical unit such as a spring to move the door.

There is a need for a more efficient door operator system that reduces the complexity and the risks of the door operator system during operation, maintenance and installation.

Summary

An object of the present disclosure is to provide a door operator system which seeks to mitigate, alleviate, or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination.

An object of the present invention is to ensure that the door sections are arranged in level and remains in level during operation. This is achieved by having at least two optical sensors mounted on each side of a door section that measures the distance to the floor.

In a first aspect, a sectional door operator system for opening and closing an opening is provided. The sectional door operator system comprises a door arranged to be moved between an open and closed position and comprising a plurality of horizontal and interconnected sections, and a drive unit arranged to move the sectional door from the closed position to the open position. The sectional door operator system further comprises a sensor system comprising a control unit, being in operative communication with the drive unit, and at least a first optical sensor and a second optical sensor. The first optical sensor and the second optical sensor are mounted at different vertical sides of a vertical axis, wherein said first optical sensor and said second optical sensor each are arranged on any section of the plurality of horizontal and interconnected sections. The control unit is configured to receive position data from said first optical sensor, wherein said position data comprises information of the position of the section to which the first optical sensor is arranged in relation to a ground level, receive position data from said second optical sensor, wherein said position data comprises information of the position of the section to which the second optical sensor is arranged in relation to the ground level, determine if there is a deviation between the position data from the first optical sensor and the position data from the second optical sensor that is above a maximum deviation threshold, and when a deviation that is above a maximum deviation threshold is determined, transmit an alignment signal to the drive unit.

In one embodiment the drive unit comprises at least a first motor and a second motor. The drive unit may be mounted on one section of the plurality of horizontal and interconnected sections. The first motor and the second motor may be mounted at different vertical sides of the horizontal and interconnected section.

In one embodiment the alignment signal comprises instructions that causes alternation of the operation of at least the first motor and/or the second motor in order to align at least one of the horizontal and interconnected sections. The alignment signal may comprise instructions that alters the speed of the first motor or the second motor.

In one embodiment the sectional door operator further comprises a door frame comprising a first frame section at a first side of the opening and a second frame section at a second side of the opening, wherein the plurality of horizontal and interconnected sections are connected to the door frame. In one embodiment, the first motor is moveably connected to the first frame section and the second motor is moveably connected to the second frame section.

In one embodiment the first optical sensor and the second optical sensor are Time-of- Flight sensors.

In a second aspect a method of controlling the operation of a door comprising a plurality of horizontal and interconnected sections in a sectional door operator system is provided. The sectional door operator system furthermore comprises a drive unit and a sensor system, wherein the sensor system comprises a control unit, being in operative communication with the drive unit, and at least a first optical sensor and a second optical sensor, and wherein said first optical sensor and said second optical sensor are mounted at different vertical sides of a central axis, and wherein said first optical sensor and said second optical sensor each are arranged on any section of the plurality of horizontal and interconnected sections. The method comprises receiving position data from said first optical sensor, wherein said position data comprises information of the position of the section to which the first optical sensor is arranged in relation to a ground level, receiving position data from said second optical sensor, wherein said position data comprises information of the position of the section to which the second optical sensor is arranged in relation to the ground level, determining if there is a deviation between the position data from the first optical sensor and the position data from the second optical sensor that is above a maximum deviation threshold, and when a deviation that is above a maximum deviation threshold is determined, transmitting an alignment signal to the drive unit.

The method can be performed during an installation phase. The method could also be used continuously during operation. The method could yet further be used during maintenance.

In one embodiment, the method further comprises determining if the accuracy of the position readings are above a predetermined threshold value, wherein when it is determined that the accuracy of the position are below the predetermined threshold value transmitting a movement signal to the drive unit. The movement signal may cause a movement of the door section in a direction towards the ground level.

Embodiments of the invention are defined by the appended dependent claims and are further explained in the detailed description section as well as in the drawings.

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

A reference to an entity being “designed for” doing something in this document is intended to mean the same as the entity being “configured for”, or “intentionally adapted for” doing this very something.

Brief description of the drawings

The foregoing will be apparent from the following more particular description of the example embodiments, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the example embodiments.

Figure l is a schematic perspective view of a door operator system comprising a sectional door in a closed position. Figure 2a is a schematic side view of a door operator system comprising a sectional door in an open position.

Figure 2b is a schematic side view of a door operator system comprising a sectional door in an intermediate position. Figure 2c is a schematic side view of a door operator system comprising a sectional door in a closed position.

Figure 3a is a schematic view of a section of a sectional door in an intermediate position and optical sensors generally according to the present invention.

Figure 3b is a schematic view of a section of a sectional door in an intermediate position and optical sensors generally according to the present invention.

Figure 4a is a schematic perspective view of a door operator system comprising a sectional door in a closed position.

Figure 4b is a schematic perspective view of a door operator system comprising a sectional door in a closed position. Figure 5a is a schematic block diagram representing parts of a door operator system according to the present invention.

Figure 5b is a schematic block diagram representing parts of a door operator system according to the present invention.

Figure 5c is a schematic block diagram representing parts of a door operator system according to the present invention.

Figure 6a is a schematic illustration of a method of a control unit arranged in the door operator system.

Figure 6b is a schematic illustration of a method of a control unit arranged in the door operator system. Figure 7 is a schematic illustration of a method of a control unit arranged in the door operator system.

Detailed description

Embodiments of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.

Figures 1-4 all illustrates a sectional door operator system. However, as should be understood by a person skilled in the art, the inventive aspects of the present invention are also applicable to a door operator system that is a single blade door operator system.

Figures 1-2 are schematic views of a door operator system 1 in which the inventive aspects of the present invention may be applied. The door operator system comprises a door frame 3, a drive unit 10 and a door 8. The door operator system 1 is arranged to be installed in an opening 2 defined by a wall 50 and a floor 23. The door operator system 1 is arranged to open and close the opening 2 by moving the door 8 between an open position O, as disclosed in Figure 2a, and a closed position C, as disclosed in Figure 1 and 2c.

In this embodiment, the door 8 is a sectional door 8 comprising a plurality of horizontal and interconnected sections 9a-e connected to the door frame 3. In one embodiment, the door is a garage door. In an alternative embodiment, the door is an industrial door. The door 8 is arranged to be moved along the door frame 3 between the closed position C and the open position O.

In one embodiment, the door operator system is an up and over door operator system. A up and over door operator system is a system in which the door in the closed position C is arranged substantially vertical and in the open position O is arranged substantially horizontal and inside of the opening.

In an alternative embodiment, the door operator system is an up and up door operator system. A up and up door operator system is a system in which the door in the closed position C is arranged substantially vertical and in the open position O is arranged substantially vertical above the opening.

The door frame 3 comprise a first frame section 4 at a first side 5 of the opening 2 and a second frame section 6 at a second side 7 of the opening 2. The door frame 3 is connected to the wall 50 and to the floor 23. The floor or ground 23 is representing at a ground level. The first frame section 4 comprises a substantially vertical part 4a and a substantially horizontal part 4b. The second frame section 6 comprises a substantially vertical part 6a and a substantially horizontal part 6b. The vertical part 4a, 6a and the horizontal part 4b, 6b are connected to create a path for the door 8 to glide on and a track for the drive unit 10 to interact with.

The door 8 is directly or indirectly connected to the door frame 3. The door 8 is at a first side moveably connected to the first frame section 4 and at a second side moveably connected to the second frame section 6. In one embodiment, one or more of the plurality of sections 9a-e is connected to the first frame section 4 at said first side 5 and to the second frame section 6 at said second side 7.

In one embodiment, the door 8 could be horizontal, or at least at an angle in view of the closed position C, and the door 8 is positioned inside of the opening 2 and above the opening 2. When moving from the closed position C to the open position O, the sections 9 of the door that are interconnected will push on each other such that the whole door 8 will move upwards. The sections 9 will rotate and move in relation to each other when moving from a vertical position to the horizontal position.

The drive unit 10 comprise at least a first motor 11a and a second motor 1 lb (as shown in Figure 3a). The drive unit 10 may further comprises at least one battery 12. The at least one battery (not shown) arranged to power at least one of the motors 11a, 1 lb is at least connected to one of the first or second motor 11a, 1 lb. In one embodiment, the at least two motors 11a,

1 lb are connected to one battery. In an alternative embodiment, one or more batteries are connected to each motor 11a, 1 lb. In yet one embodiment, the first motor 11a is connected to a first battery and the second motor 1 lb is connected to a second battery. The drive unit 10 is connected and/or mounted to the door 8.

In one embodiment, as will be described more in relation to Figure 3a, the drive unit 10 is mounted to a section 9e, i.e. one of said plurality of horizontal and interconnected sections, of the door 8. The first motor 11a and the second motor 1 lb are arranged on the same section 9e. Preferably, the first motor 11a and the second motor 1 lb are arranged at different vertical sides of a central axis A. The central axis A is preferably arranged in the centre portion of the section . Hence, in one embodiment the first motor 11a and the second motor 1 lb are arranged at different vertical sides the section 9e. Each motor 11a, 1 lb is thus arranged in conjunction to the first frame section 4 and the second frame section 6, respectively.

The drive unit 10 is further connected to the door frame 3. The drive unit 10 is at a first side moveably connected to the first frame section 4 and at a second side moveably connected to the second frame section 6. Hence, the first motor 1 la is moveably connected to the first frame section 4 and the second motor 1 lb is moveably connected to the second frame section 6. The drive unit 10 is arranged to interact with the door frame 3 to move the sectional door 8 from the closed position C to the open position O and from the open position O to the closed position C.

In one embodiment, at least one motor 11 of the first and second motor 11 is configured to brake the movement of the sectional door 8 when the sectional door 8 is moved from the open position O to the closed position C. In one embodiment, both the first and second motor 11 are configured to brake the movement of the sectional door 8 when the sectional door 8 is moved from the open position O to the closed position C.

In one embodiment the door operator system 1 further comprises, as an optional feature, at least one charging unit 13, 14. In one embodiment, as disclosed in Figure 1, the system 1 comprises a first charging unit 13 and a second charging unit 14. The charging units 13, 14 are preferably connected to the door frame 3. The first charging unit 13 is mounted in a position that correlates with the position of the battery 12 of the drive unit 10 when the sectional door 8 is in the closed position C. The first charging unit 13 is arranged to be connected to and to charge the at least one battery 12 in the closed position. The second charging unit 14 is mounted in a position that correlates with the position of the battery 12 of the drive unit 10 when the sectional door 8 is in the open position C. The first charging unit 14 is arranged to be connected to and to charge the at least one battery in the open position.

In one embodiment, at least one motor 11a, 1 lb of the drive unit 10 is configured to act as a generator and to charge the at least one battery when the sectional door 8 is moved from the open position O to the closed position C. In one embodiment, both the first and second motor 11a, 1 lb of the drive unit 10 is configured to act as a generator and to charge the at least one battery when the sectional door 8 is moved from the open position O to the closed position C.

In one embodiment, the at least first and second motor 11 of the drive unit 10 are direct current DC motors 11. In a preferred embodiment, the at least first and second motor 11a, lib are brushless direct current (BLDC) motors.

At least one motor 11a, 1 lb of the first and second motor of the drive unit 10 may further comprise a brake (not shown). In one embodiment, both the first and the second motor comprises the brake. In one embodiment, the brake is an electromagnetic brake. The brake is arranged to control/reduce the speed of the door 8 when it is moved from the open position O to the closed position C.

The drive unit 10 may comprise at least a first and second pinion (not shown), wherein the first pinion is connected to the first motor 11a and the second pinion is connected to the second motor 1 lb. The pinions are rotated by the motors 11 when the motors 11 are running. The pinions rotates the motors 11 when the weight of the door 8 moves the door 8.

In one embodiment, the drive unit 10 comprise at least a first and a second wheel (not shown). In one embodiment, the wheels are connected to the motors 11a, 1 lb. In an alternative embodiment, the wheels are connected to the pinions of the drive unit 10. The wheels may be arranged to be rotated by the motors 11. In one embodiment, the door frame 3 comprises a guide track (not shown). In one embodiment, the guide track is connected to the first and second frame section 4, 6. In an alternative embodiment, the guide track is an integrated part of the first and second frame section 4, 6. The wheels are adapted to be inserted into the guide track. The wheels are arranged to interact with the guide track and to restrict horizontal movement of the wheels when the wheels, and thus also the drive unit 10 and the door 8, is moved between the open and closed position O, C of the door 8.

In one embodiment, the drive unit 10 comprise at least a first and a second spline joint 15. The first spline joint 15 is in one end connected to the first wheel and in a second end connected to the first motor 11. The second spline joint 15 is in one end connected to the second wheel and in a second end connected to the second motor 11. As the guide track is arranged to restrict horizontal movement of the wheels and the wheels are connected to the motors 11, the spline joints 15 will move and compensate for any horizontal movement of the drive unit 10 and the door 8 in relation to the door frame 3. The spline joints 15 will be compressed when the distance between the motors 11 and the door frame 3 decreases. The spline joints 15 will be extracted when the distance between the motors 11 and the door frame increases. In one embodiment, the spline joints 15 are arranged to compensate for horizontal movements of the first and second motor 11 in relation to the first and second frame section 4,

6, respectively. In one embodiment, the wheels are connected to the spline joints 15 of the drive unit 10.

The door frame 3 may comprise a rack (not shown). In one embodiment, the first and the second frame sections 4, 6 of the door frame comprise the rack. The rack of the door frame 3 is arranged to interact with said at least first and second pinion of the drive unit 3 to move the door 8. The connection between the drive unit 10 and the door frame 3 is not restricted to a rack and pinion connection and could be achieved by means of one or more of a belt drive, a magnetic drive or a friction drive. Both the first and the second frame section 4, 6 accordingly comprises the rack.

As been described above, both motors continuously track the movement between two end points and synchronize the position to the other motor. During the installation, the motors has no record of the position within the doorframe. The motors thus needs to be initialized with the distance to the floor, as well as an initial positioning so that the door is in level. During operation, small error in the tracking of position can accumulate over time so that the door no longer is in level. Hence, it is beneficial if the position of the motors can be recalibrated before the drift in position is too big for the door to be considered in level. The inventors of the present invention has realized that this can be achieved by a sensor system 100. As is shown and will be described more in detail with reference to Figures 3-5, the door operator system 1 further comprises a sensor system 100 that comprises at least two optical sensors 31, 32 and a control unit 20. It should be noted that the sensors 31, 32 are present, although not shown, also in the embodiments illustrated in Figure 1-2.

The control unit 20 is in operative communication with the drive unit 10. The control unit 20 may be in wired communication with the two motors 11a, 1 lb or be in a wireless communication. The control unit 20 is further in operative communication with the sensing elements 31, 32. The communication may either be wired or wireless.

The control unit 20 is configured to control the movement of the drive unit 10, i.e. when and how the drive unit 10, and its associated motors 11a, 1 lb, should move the door 8. The control unit 20 is arranged to receive input of if the door 8 should be opened or closed. In one embodiment, the control unit 20 is arranged to receive the input from one or more of a user interface, a mechanical button or a remote control.

The control unit 20 is further configured to control the operation of the at least first and second motors 11a, 1 lb. In a preferred embodiment, the control unit 20 is configured to control and adjust the operating speed of one or all of the motors 11a, lib. The motor may comprise sensing elements (not shown), for example in the case of where the motors 11a, lib are a brushless DC electric motor, or be in connection to a sensing element (not shown) in form of a rotary encoder. The control unit 20 may alter the speed of the one or more motors in response to operational data gathered by the sensing elements 31, 32. The operational data may be used to alter the speed of one of the motors to achieve the preferred situation where the motors are arranged in sync with each other.

Turning back to Figures 3a-b, the optical sensors 31, 32 will be described more in detail. The optical sensors 31, 32 are preferably time of flight (ToF) sensor. The Time-of-Flight principle is a method for measuring the distance between a sensor and an object, based on the time difference between the emission of a signal and its return to the sensor, after being reflected by an object. Hence, a time of flight sensor transmits one or more light pulses towards a surface of an object, in this case the floor or ground 32, which the reflects back to the source and/or sensor. The time for this reflection is measured, and the distance can be calculated with high precision. The optical sensors 31, 32 may be direct ToF-sensors or indirect ToF-sensors. A direct ToF-sensor sends out short pulses of light (a few nanoseconds) and then measures the time it takes for some of the emitted light to come back. An indirect ToF-sensor sends out continuous, modulated light and measures the phase of the reflected light to calculate the distance to an object.

The optical sensors 31, 32 may be configured to transmit and receive infrared light. The optical sensors 31, 32 may comprise LED’s and/or a laser source.

The at least two optical sensors 31, 32 are preferably arranged at a section 9e, i.e. one of said plurality of horizontal and interconnected sections, of the door 8. The first optical sensor 31 and the second optical sensor 32 are arranged on the same section 9e. Preferably, the first optical sensor 31 and the second optical sensor 32 are arranged at different vertical sides of the central axis A. The central axis A is preferably arranged in the centre of the arrangement, i.e. in the centre portion of one section 9e. It is preferred if the first and second optical sensors 31, 32 are arranged at the lowermost section 9e. In one embodiment, the optical sensors 31, 32 are arranged on the same section 9e. In this embodiment the optical sensors are arranged on the same section as the first and second motor 11a, 1 lb. However, it should be noted that the optical sensors 31, 32 need not be arranged on the same section as long as they are arranged at different vertical sides of the central axis A (as shown in Figure 4a).

The first optical sensor 31 and the second optical sensor 32 are preferably arranged at the same height from the lower end of the door section 9e. The optical sensors 31, 32 may be arranged at a horizontal edge of the lower end of the door section 9e. In one embodiment, the optical sensors 31, 32 are arranged from a distance from said edge. In one embodiment, the optical sensors are centrally arranged in the vertical extension of the section 9e. The first optical sensor 31 and the second optical sensor 32 are preferably arranged at the same distance from a respective vertical edge of the section 9e.

If the first optical sensor 31 and the second optical sensor 32 are not arranged at the same height from the ground level, it is preferred if their difference in height is saved, and used to adapt the distance measured to the ground.

In Figures 3a-b and 4a, two optical sensors 31, 32 are present, however as will be shown in Figure 4b, there might be an additional number of optical sensors.

Each optical sensor 31, 32 is configured to determine the distance dl, d2 to the ground 32. In the illustrative embodiments of Figures 3a-b, the distance measured the first optical sensor 31 is referred to as dl and the distance measured by the second optical sensor 32 is referred to as d2. In Figure 3a-b, the door section 9e is aligned with the floor 32 and the distance dl is equal to the distance d2.

In Figure 3b, the distance dl measured by the first optical sensor 31 is smaller than the distance d2 measured by the second optical sensor 32. The difference in distance between dl and d2 in Figure 3b has been exaggerated in order to be illustrative. In this situation, the door section 9e is not aligned with the floor 32, and the position of the door section 9e thus has to be corrected.

By using the optical sensors 31, 32 mounted on each side of the central axis A of the door, the distance to the floor can be measured with high precision. This information is used to control that the door that is to be installed is automatically installed in level. Moreover, this information is also used to automatically correct the position of the sides of the door during each cycle of the door so that the door remains in level during operation. When the difference in measured distance is larger than a maximum threshold, the motors on the door can be operated individually up or down until the difference in measured distance is below an allowable threshold. This procedure will be further described in more detail with reference to Figure 6 and 7.

As previously described the drive unit 10 may comprise at least the first and the second motor 11 mounted on the first section 9e of the door 8. The first motor 11 is moveably connected to the first frame section 4 and the second motor 11 is moveably connected to the second frame section 6. In accordance with the aforementioned, the drive unit may further comprise additional motors which will now be described further with reference to Figures 4a-b.

In one embodiment, the drive unit 10 comprises a third and a fourth motor 1 lc-d mounted on a second horizontal section 9 of the horizontal sections and arranged to assist the first and second motors 1 la-b when moving the sectional door 8 from the closed position C to the open position O. The third and fourth motors 11 are connected to the control unit 20 and arranged to be controlled by the control unit 20 in the same way as described above in relation to the first and second motor 11.

In the embodiment show in in Figure 4a, the sectional door operator system comprises four motors 1 la-d and a first and a second optical sensors 31, 32. The first and second optical sensors 31, 32 are arranged at different sides of the central axis A. In this embodiment, the first and second optical sensors are not arranged on the same section. Instead, one optical sensor is arranged on the sections 9e and a second optical sensors is arranged on the section 9c. In this embodiment, the section that is arranged with a motor is also arranged with at least one optical sensor. In the embodiment shown in Figure 4b, the sectional door operator system comprises four motors 1 la-d and a four optical sensors 31, 32, 33, 34. The first and second motor 11a, lib are arranged on one section 9e and the third and fourth motor 11c, 1 Id are arranged on another section 9c. The first and second optical sensors 31, 32 are arranged on the same section 9e as the first and second motor 11a, 1 lb and the third and fourth optical sensors 33, 34 are arranged at the same section as the third and fourth motor 11c, lid.

It should be understood that other configurations of the setup with sensors 31-34 and motors 1 la-d are possible within the scope of the inventive concept.

In one embodiment, the control unit 20 is configured to control and adjust the operating speed of one or all of the motors 11a, lib, 11c, 1 Id in response to position data from the at least two optical sensors. This will now be described in detail with reference to Figures 5a-c.

Figure 5a illustrates one embodiment of a sensor system 100 comprising a control unit 20 and two optical sensors 31, 32. The optical sensors 31, 32 determines the distance to the floor or ground 23. This position data 41, 42 (comprising the distance dl, d2) is transmitted to the control unit 20. The control unit 20 is configured to evaluate the position data 41, 42 from the optical sensors 31, 32. The control unit 20 is preferably configured to compare the determined distances dl, d2 to each other in order to detect any deviation. Depending on the evaluation of the position data 41, 42 from the at least two optical sensors 31, 32 the control unit 20 may be configured to transmit an alignment signal 43a, 43b to the first motor 11a and/or the second motor lib.

In the setup as illustrated in Fig. 4a, the setup could either be made as in Figure 5a or as in Figure 5b. In one embodiment, as shown in Figure 5a, the control unit 20 is configured, based on the evaluation of the position data 41, 42 from the at least two optical sensors 31, 32, to transmit an alignment signal 43a, 43b to the first motor 11a or the second motor 1 lb.

In one embodiment, as shown in Figure 5b, the control unit 20 is configured, based on the evaluation of the position data 41, 42 from the at least two optical sensors 31, 32, to transmit an alignment signal 43a, 43b to the first motor 11a or the second motor 1 lb, to the third motor 1 lc or the fourth motor lid, or to both the first motor 11a and the third motor 11c or to both the second motor 1 lb and fourth motor lid.

In the following example, the part of the door section being closest to the first frame section 4 is at a distance from the ground 23 that is shorter than the distance from the part of the door section being closest to the second frame section 6 (similar to the situation in Figure 3b).

In this example, the miss-alignment will be corrected by lowering the part of the door section being closest to the second frame section 6 so that it is in level with the part of the door section being closest to the first frame section 4. This may be achieved by increasing the speed of the second motor 1 lb and/or by increasing the speed of the fourth motor lid. Hence, the speed of the motor(s) that are arranged on the side that is to be corrected is changed.

In the setup as illustrated in Fig. 4b, the setup could be made as in Figure 5c. The control unit 20 may be configured to receive position data 41, 42 from the first and second optical sensors 31, 32 and based on said evaluation transmit an alignment signal 43a, 43b to the first motor 11a or the second motor 1 lb. Similarly, the control unit 20 may be configured to receive position data 4G, 42’ from the third and fourth optical sensors 32, 33 and based on said evaluation transmit an alignment signal 43 c, 43 d to the third motor 1 lc or the fourth motor lid.

Alternatively, the control unit 20 is configured, based on the evaluation of the position data 41, 42 from the at least four optical sensors 31, 32, 33, 34, to transmit an alignment signal 43a, 43b to the first motor 11a or the second motor 1 lb, to the third motor 11c or the fourth motor 1 Id, or to both the first motor 11a and the third motor 1 lc or to both the second motor 1 lb and fourth motor lid.

As should be understood by a person skilled in the art, combinations of the different implementations described above are also possible. Moreover, although not shown each optical sensor may be provided with an internal control unit which performs one or more of the steps described for the control unit 20. For example, each optical sensor 31, 32 may be arranged with a control unit which in turn communicates to a common control unit 20 which then transmits the alignment signal(s) to the motor(s).

Figures 6a-b, shows methods implemented by the control unit 20 to control the alignment of the door sections 9e relative the floor or ground 23. In Figure 6a, the control unit 20 is configured to receive 110 position data from the first optical sensor 31 and to receive 112 position data from the first optical sensor 32. The position data comprises information of the position of the section 9e in relation to the ground level 23.

The control unit 120 is configured to evaluate 114 the position data. The evaluation step may for example comprise comparing the measured distances for each sensor. The control unit 120 is configured to determine 116 if there is a deviation between the position data originating from the first optical sensor 31 and the position data from the second optical sensor 32 that is above a maximum deviation threshold. The deviation may be seen as a difference in distance (i.e. a delta). The deviation may be determined by determining if there is a deviation between the measured distances dl, d2 that is above a maximum predetermined deviation threshold.

If it is determined that a deviation that is above a maximum deviation exists, an alignment signal is transmitted 118 to the drive unit 10. The alignment signal comprises information relating to a change in operation of the drive unit that will result in a decrease in deviation between the gathered position data. In one embodiment, the alignment signal causes a change in speed of the motors.

If not deviation above a maximum threshold exists, no transmittal 120 of an alignment signal is sent. The relative speed of the motors is thus maintained as it has been determined that no miss-alignment of the section 9e exists.

In one embodiment, during closure, if the second optical sensor 32 measures a distance that is further away from the ground 23 than the first optical sensor 31, the speed of the first motor 11a will be reduced. This allows the second motor 1 lb to catch up with the first motor 1 la so that they are at the same position, thus making the section 9e aligned.

In the same way, during closure, if the first optical sensor 31 measures a distance that is further away from the ground 23 than the second optical sensor 32, the speed of the second motor 1 lb will be reduced. This allows the first motor 1 la to catch up with the second motor 1 lb so that the section 9e gets aligned.

In an alternative embodiment, if the second optical sensor 32 measures a distance that is further away from the ground 23 than the than the first optical sensor 31, the speed of the second motor 1 lb will be increased. This allows the second motor 1 lb to catch up with the first motor 1 la so that they are at the same position, so that the door sections are aligned.

Figure 6b illustrates the situation where a deviation is determined to be above a maximum deviation threshold. As previously described, an alignment signal will be transmitted to the control unit 20 to alter the speed of one of the motors 11a, 1 lb. In a next step, 122a-b, the control unit is configured to receive position data from the first optical sensor 31 and to receive position data from the first optical sensor 32.

The control unit 120 is configured to determine 124 if there is a deviation between the position data originating from the first optical sensor 31 and the position data from the second optical sensor 32 that is below an allowable deviation threshold.

If it is determined that the deviation of the position data is below the allowable deviation threshold, the control unit will stop 126 the alternation in speed of the motors.

If it is determined that the deviation of the position data is above the allowable deviation, the change of speed of the motors will be continued, and the process will be repeated.

Hence, when the difference in measured distance is larger than a maximum threshold, the motors on the door can be operated individually up or down until the difference in measured distance is below an allowable threshold. An embodiment of the control unit 20 is described with more details with reference to Figure 7.

In a first step 202, the control unit 20 receives information regarding position data from the first optical sensor 31 and the second optical sensor 32. The position data received from the first optical sensor 31 comprises the distance measured between the ground 23 and the first optical sensor 31. The position data received from the second optical sensor 32 comprises the distance measured between the ground 23 and the second optical sensor 32.

In a next, optional, step 204, it is determined if the accuracy of the position readings are sufficient. If it is determined that the accuracy of the position readings are sufficient, the method continues to step 208. Optical sensors generally provide more accurate results when the distance measured is short. Hence, it is beneficial to measure the distances when the door section 9e is close to the ground level 23.

If it is determined 206 that the accuracy of the position readings are not sufficient, i.e. not above an accuracy threshold value, the control unit 20 is configured to transmit a movement signal to the drive unit 10. The movement signal will cause a movement of the door sections 9a- e downwards, i.e. in a direction towards the ground/floor 23. If the motors 11a, 1 lb are still, i.e. not moving, the movement signal will initiate a movement of the door sections 9a-e. If the motors 11a, lib already are moving in a downward direction, the movement signal may cause an increase in the speed or a maintenance of the speed.

Step 202 is then repeated. The step of receiving position data from the optical sensors 31, 32 may be initiated after a predetermined time period, or when the drive unit 11a, lib has driven the door sections 9a-e a predetermined distance. The step 204 may be repeated in order to see if the accuracy of the positon readings are sufficient.

In a next step 208, the deviation between the position data from the first and second optical sensors 31, 323 is calculated.

If the deviation is above predetermined threshold 210, representing a maximum normal deviation in position, the control unit transmits 212 an alignment signal to the drive unit 10. The drive unit 10 changes the speed of one of the motors in order to align the door section(s). If the deviation is below the predetermined threshold, no alignment signal is transmitted. The speed of the motors are not altered. Hence, both motors are driven with the same speed.

The invention has been described above in detail with reference to embodiments thereof. However, as is readily understood by those skilled in the art, other embodiments are equally possible within the scope of the present invention, as defined by the appended claims. It is recalled that the invention may generally be applied in or to an entrance system having one or more movable door member not limited to any specific type. The or each such door member may, for instance, be a swing door member, a revolving door member, a sliding door member, an overhead sectional door member, a horizontal folding door member or a pull-up (vertical lifting) door member.