Patent Publication Number: US-8115438-B2

Title: Aperture closure member control arrangements

Description:
This is a national stage application filed under 35 USC 371 based on International Application No. PCT/GB2007/001641 filed May 3, 2007, and claims priority under 35 USC 119 of United Kingdom Patent Application No. 0608973.4 filed May 6, 2006. 
     The present invention relates to control arrangements for aperture closure members. 
     Motorised aperture closure members are used for a variety of purposes, such as for domestic garage doors, factory and warehouse doors and the like. Types of aperture closure member include flexible members made of reinforced fabric or sheet metal, or sectional closures made of separate sections which are articulated to each other. These closure members can be moved along curved tracks or rolled around rollers or drums in order to open and close the corresponding aperture. Typically, the closure member moves vertically, either rolling on and off a roll above the aperture, or onto and off a track extending inwardly from the top of the aperture. 
     An electric motor is commonly used for driving the movement of the aperture closure member. It is desirable to monitor the movement, for various reasons. For example, it may be desirable to slow down the member, when approaching the extremes of its movement, and to sense and respond to any resistance to movement which may arise as the result of a fault, or because the closure member encounters a foreign body blocking the aperture. 
     Embodiments of the present invention provide an aperture closure member control arrangement, comprising: 
     a pulse generator operable to create a train of pulses as the aperture closure member moves; 
     a counter operable to count pulses of the train to provide an indication of the position of the aperture closure member; 
     wherein the pulse generator creates first type pulses and less frequent second type pulses, and wherein the arrangement further includes a discriminator operable to discriminate between first and second type pulses, for selectively providing first or second type pulses to a counter for counting. 
     The discriminator may monitor the size, amplitude and/or pulse width of pulses received, the first and second type pulses being distinguishable by the monitored parameter or parameters. The selection of pulses made by the discriminator for provision to the counter may be dependent on the count value at the time. One type of pulse may be counted until a threshold count is reached, the other type of pulse being counted thereafter. The second type pulses may be counted until the threshold is reached. 
     The pulses may be created by a member which rotates as the aperture closure member moves. The rotatable member may have a ring of features, there being a sensor operable to sense the passing of the features as the member rotates, to create pulses for counting. The features may be teeth formed around the rotatable member. The passage of features may create first type pulses. Features may be provided at regular intervals around the ring, there being at least one position around the ring at which the regularity is disturbed, to form an irregularity which creates second type pulses. A feature may be omitted from a regular position, to create the irregularity. Alternatively, a feature may be irregularly large to create the irregularity. 
     If the features are teeth, the irregularity may be formed by omitting a tooth or by creating a tooth of abnormal size. 
     The sensor may include a magnet and a Hall effect sensor, both in proximity with the rotatable member to sense changes in magnetic field as the features pass the sensor. 
     In another aspect, embodiments of the invention provide an aperture closure member control arrangement comprising: 
     a rotatable member which rotates as the aperture closure member moves; 
     a sensor; 
     a ring of features on the rotatable member and able to be sensed by passing the sensor to create a train of first type pulses; 
     wherein the ring of features includes an irregularity at least one position, to create a second type pulse within the train. 
     The first and second type pulses may be distinguishable by size, amplitude and/or pulse width. The features may be discernible optically, magnetically or mechanically. The features may be teeth. 
     The features may be of magnetic material, there being an associated magnet arranged so that the passing of features creates a detectable change in the magnetic field in the vicinity of the magnet. The sensor may include a magnetic sensor operable to sense magnetic changes as the features pass. 
     The features may be teeth formed around the rotatable member. The passage of features may create first type pulses. Features may be provided at regular intervals around the ring, there being at least one position around the ring at which the regularity is disturbed, to form an irregularity which creates second type pulses. A feature may be omitted from a regular position, to create the irregularity. Alternatively, a feature may be irregularly large to create the irregularity. 
     If the features are teeth, the irregularity may be formed by omitting a tooth or by creating a tooth of abnormal size. 
     The sensor may include a magnet and a Hall effect sensor, both in proximity with the rotatable member to sense changes in magnetic field as the features pass the sensor. 
     In a further aspect, embodiments of the invention provide an aperture closure member control arrangement comprising: 
     a control circuit operable to provide electrical power to a motor to drive the aperture closure member, when required; 
     a current supply powered from the motor supply to return a signal current to the control circuit; 
     and a sensor operable to modulate the signal current in accordance with movement of the aperture closure member, for sensing at the control circuit. 
     The current supply may be powered by a first polarity of the motor supply, the signal current being connected to another polarity of the motor supply, at the control circuit. The signal current may be carried by a single conductor from the sensor to the control circuit. 
     The current supply may include a Darlington pair of transistors, having a base to which the output of the sensor is applied, to modulate the current supplied. 
     The control circuit may be located remotely of the motor, for manual access to the control circuit without proximity to the motor. 
     The sensor may sense movement of a rotatable member which rotates as the aperture closure member moves. The rotatable member may have a ring of features able to be sensed by passing the sensor to create a train of pulses. The ring of features may create a train of first type pulses, the ring of features also including an irregularity at least one position, to create a second type pulse within the train. 
     The first and second type pulses may be distinguishable by size, amplitude and/or pulse width. The features may be discernible optically, magnetically or mechanically. The features may be teeth. 
     The features may be of magnetic material, there being an associated magnet arranged so that the passing of features creates a detectable change in the magnetic field in the vicinity of the magnet. The sensor may include a magnetic sensor operable to sense magnetic changes as the features pass. 
     The features may be teeth formed around the rotatable member. The passage of features may create first type pulses. Features may be provided at regular intervals around the ring, there being at least one position around the ring at which the regularity is disturbed, to form an irregularity which creates second type pulses. A feature may be omitted from a regular position, to create the irregularity. Alternatively, a feature may be irregularly large to create the irregularity. 
     If the features are teeth, the irregularity may be formed by omitting a tooth or by creating a tooth of abnormal size. 
     The sensor may include a magnet and a Hall effect sensor, both in proximity with the rotatable member to sense changes in magnetic field as the features pass the sensor. 
     Embodiments of the invention may incorporate any feature or combination of features of any of the aspects set out above, or of a combination of the aspects. 
    
    
     
       Embodiments of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: 
         FIG. 1  is a highly schematic, part cut-away perspective view of an example of an aperture closure arrangement with which the present invention may be used, and 
         FIG. 2  is a simplified elevation view of part of the arrangement; 
         FIG. 3  is a partial perspective view, on an enlarged scale, of principal components of a sensor arrangement for one example of a monitoring arrangement of the present invention; 
         FIG. 4  schematically illustrates the magnetic effects within the sensor of  FIG. 3 ; 
         FIG. 5  indicates the output waveform of the sensor of  FIG. 3 ; 
         FIG. 6  illustrates in simplified form the manner in which signals are passed to a control circuit; and 
         FIG. 7  illustrates the arrangements of  FIG. 6 , in more detail. 
     
    
    
       FIG. 1  illustrates an aperture closure member arrangement  10 . A closure member  12 , in the form of a door, is guided along a track  14 . The door  12  is shown as articulated slats  12 A but may alternatively be flexible reinforced fabric or sheet metal, for example, as noted above. 
     The track  14  has a generally vertical leg  14 A. As the door  12  moves up the vertical track  14 A, it may either pass onto a generally horizontal leg  14 B, or be rolled (not shown). The door  12  is moved by a shaft  16  which is in turn driven by a DC electric motor  18  through two pulley wheels  18 A connected by a drive belt  18 B, as shown schematically in  FIG. 2 . 
     A similar track (not shown) is provided at the other side of the door  12 . The tracks are installed with the vertical legs extending up either side of the aperture to be closed (such as an aperture in the outer wall of a building). The horizontal legs of the tracks extend back from the aperture, into the building. When the door is closed, it forms a vertical barrier between the vertical legs of the tracks. To open the door, the motor  18  is used to turn the shaft  16 , moving the door up to the horizontal legs of the tracks, or rolling the door around the axis of the shaft  16 . 
     In the examples being described, the motor has a fast speed and a slow speed, the latter being used when the door is approaching the ends of its range of movement. 
     The shaft  16  carries a rotatable member in the form of a disc  20  ( FIG. 2 ) which rotates as the shaft  16  rotates. Consequently, the disc  20  rotates as the door  12  moves. A sensor  22  is provided to detect rotation of the disc  20 , and thus to detect movement of the door  12 . 
     The disc  20  ( FIG. 3 ) has a ring of features  24 , which are teeth in this example. The sensor  22  is able to sense the teeth  24 , as they pass. In this example, the features  24  are a ring of circumferential teeth around the disc  20 , being spaced regularly around the disc  20 , but including an irregularity  26  at least one position around the disc  20 . The irregularity  26  is provided, in this example, by a tooth missing from the otherwise regular ring of teeth  24 , to create an irregularly large gap between adjacent teeth. The location of the missing tooth is indicated in  FIG. 3  by broken lines. In an alternative, a tooth of abnormal size may be created, for example by joining two adjacent teeth  24 . The abnormal size tooth forms an irregularity in an otherwise regular line of teeth. 
     The passing of the teeth  24  creates first type pulses from the sensor  22 , as will be described. The passing of the irregularity  26  creates a second type pulse from the sensor  22 , as will be described. 
     The sensor  22  includes a Hall effect sensor  28  and an associated magnet  30 , for example a permanent magnet. The sensor  28  and magnet  30  are placed in close proximity to the ring of teeth  24 , so that the teeth  24  pass through a region  32  ( FIG. 4 ) in which a magnetic field exists, created by the magnet  30  and affecting the sensor  28 . 
     As the teeth  24  pass the sensor  28 , the magnetic field in the region  32  is affected. For example, the amount of magnetic material provided by the teeth  24 , within the region  32 , reduces on each occasion that a gap  34  between adjacent teeth  24  passes through the region  32 . A much greater deviation arises when the irregularity  26  passes through the region  32 , because of the missing tooth. 
     The waveform  36  from the sensor  28  is illustrated schematically in  FIG. 5 . The waveform  36  consists primarily of cyclic pulses  38  of relatively small amplitude, created by the passing of the teeth  24  and the gaps between them, and consequently of regular frequency and amplitude. The frequency of the small pulses  38  is linked to the speed of rotation of the disc  20 . Specifically, a complete cycle of a small pulse  38  occurs as each tooth  24  passes the sensor  28 . Less frequently, a second type pulse  40  arises. This is greater in amplitude and lower in frequency than the pulses  38 , as can be seen from  FIG. 5 . The large pulse  40  is created by the passing of the irregularity  26 , i.e. the missing tooth  26 A. The greater amplitude arises because the wider gap at the irregularity  26  results in a greater disturbance of the magnetic field in the region  32 . The lower frequency arises from the greater distance between the neighbouring teeth  24 . 
       FIG. 6  illustrates how the sensor  28  is powered, and how the output waveform  36  (illustrated in  FIG. 5 ) is used.  FIG. 6  shows a control circuit  41  which includes a power supply  42  connected at  44  to the motor  18 . The power supply  42  enables the motor  18  to be switched on or off and to be driven in either direction by reversing the polarity of the connections  44 . This results in the door  12  being moved to open or close. 
     The sensor arrangements  22 , including the disc  20 , sensor  28  and magnet  30  are illustrated in  FIG. 6  in the vicinity of the motor  18 . Power to the arrangement  22 , particularly to the sensor  28 , is drawn from the connections  44 , at the motor  18 , through rectifier diodes  46 , to take account of the polarity changes which arise on the connections  44  as the motor is reversed. 
     The arrangement  22  acts as a current supply to return a signal current at a connection  48 , back to the control circuit  41 . The arrangement  22  modulates the signal current at  48 , as will be described, in accordance with movement of the disc  20  and thus, in accordance with movement of the door  12 . This allows the movement of the door  12  to be sensed by the control circuit  41 , for reasons which will become apparent. 
     The modulated current sent at  48  has the waveform  36 . The current received at  48  by the circuit  41  is applied to a potential divider R 141 , R 41  to provide voltage to the base of a transistor TR 25 , connected as a common emitter amplifier creating an amplified voltage waveform at the collector  50 , having the waveform  36  derived from the signal current sent from the arrangement  22 . 
     The amplified waveform at  50  is applied to an analogue to digital converter  52 , and then to a discriminator-and-count circuit  54 . The circuits  52 ,  54  may either or both be implemented as appropriately programmed software-controlled processor devices. 
     The discriminator  56  of the circuit  54  is able to discriminate between small pulses  38  and large pulses  40 , by monitoring peak-to-peak amplitude and pulse width. Consequently, the discriminator  56  may either reject small pulses  38 , passing only large pulses  40  to the counter  58  of the circuit  54 , for counting, or alternatively, may reject large pulses  40 , passing only small pulses  38  to the counter  58 , for counting. 
     The discrimination implemented by the discriminator  56  is dependent on the count value at the time. In one example, large pulses  40  are initially counted when the door  12  begins to move, e.g. from the fully open position toward the closed position. Since an irregularity  26  passes the sensor  28  less frequently than teeth  24 , this results in a slow count representing a coarse monitoring of the position of the door  12 . In this example, the coarse count is maintained until indicating that the door is approaching one end of its range of movement. For example, movement of the door  12  from the fully open position to the fully closed position may be known to generate four large pulses  40 , but that the fully closed position is reached before a fifth large pulse  40  can be created. Accordingly, in this example, the discriminator  56  is initially used to reject small pulses  38 , so that the counter  58  counts large pulses until four such pulses have been counted. The discriminator  56  then begins rejecting large pulses  40  and passing small pulses  38  to the counter  58 . Small pulses are created by the passing of the teeth  24  and are therefore higher in frequency than the large pulses  40 . They correspond with a fine measurement of the door position. Accordingly, fine measurement is used only at an end region of the door travel, close to the end position. This allows the door  12  to be stopped more accurately at the desired final position, than would be possible if only large pulses  40  were counted. 
     In a preferred example, the counter  58  is a zero-crossing counter, so that the count can be changed twice for each cycle of the waveform  36 . This doubles the resolution provided for the measured position of the door  12 . 
     It can be seen from  FIG. 6  that only three connections  44 ,  48  are required, from the control circuit  41  to the motor  18  and sensor arrangement  22 . This arises because the arrangement  22  is powered from one polarity of the motor  18  locally, at the motor, being connected to the other polarity of the motor within the circuit  41 . Thus, when the control circuit  41  is located remotely of the motor  18 , which allows manual access to the control circuit without proximity to the motor  18 , only three wires are required to run between the two locations, thus simplifying and reducing the cost of installation. 
     The circuits of the sensor arrangement  22  and the control circuit  41  can be seen in more detail in  FIGS. 7A and 7B . 
       FIG. 7A  shows the control circuit  41 , including the power supply  42 . The supply  42  is DC and can be applied to the connections  44  in either polarity, according to the settings of two relays  60 . In  FIG. 7A , the relays are shown shorting together the connections  44 , thus braking the motor  18 . If either relay  60  changes state, the supply  42  is connected to the motor with corresponding polarity. Consequently, setting the relays  60  allows the motor to be switched off, or switched on to turn in either direction. 
       FIG. 7B  shows a further circuit  62  which connects the connections  44  through to the motor  18 , and also provides the circuitry of the sensor arrangement  22 . Power to the arrangement  22  is drawn from the connections  44  through rectifier diodes D 5 , D 6  (corresponding with the diodes  46  of  FIG. 6 ). This power is applied to a Darlington pair transistor TR 1  connected as a current source providing output current through an emitter resistor R 2  and a voltage regulator diode ZD 1  to the connection  48 . Specifically, the three P-N junctions of diodes D 1 , D 2 , D 2 ′ are across the base-emitter junctions of the Darlington pair TR 1  thus maintaining the Darlington pair TR 1  as a current source, the current value being set primarily by R 2 . 
     The current output of the Darlington pair TR 1  is modulated by a base voltage at  64 . This voltage is the output voltage of the Hall effect sensor  28 . Accordingly, the output current of the Darlington pair TR 1 , applied to the connection  48 , is modulated by the waveform  36  of  FIG. 5 . This modulated signal current is sent back to the control circuit  41 , over the connection  48 . 
     Returning to  FIG. 7A , the signal current from the Darlington pair TR 1  is received on the connection  48  and applied through the voltage divider R 141 , R 41  to the base of transistor TR 25 , acting as a common emitter amplifier, as has been described. The amplified output voltage appears at  50  for applying to the A to D converter  52  and discriminate-and-count circuit  54  (neither of which are illustrated in  FIG. 7A , for simplicity). 
     Many modifications can be made to the apparatus described above, without departing from the scope of the invention. For example, teeth which are detected magnetically could alternatively be detected optically or mechanically. Alternatively, other types of feature could be detected magnetically, optically or mechanically, including alternatives which can be detected by one of these means, but not others, such as variations of the magnetic properties of a mechanically uniform disc. 
     Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.