Abstract:
Method, together with the devices implementing said method, for controlling the closing and opening movements of a movable barrier ( 103 ) so as to prevent a dangerous impact with an obstacle or crushing thereof, said movable barrier ( 103 ) comprising a closing edge having, positioned thereon, one or more sensors ( 108 ) connected to a first transceiver ( 27   b ) able to exchange a signal with a second fixed transceiver ( 27   a ) in communication with a control unit which manages the movement of the barrier ( 103 ), comprising a step defining for said signal a communications protocol consisting of more than two signal configurations (A, B, C, D).

Description:
This application is a National Phase Application of International Application No. PCT/EP2005/055722, filed Nov. 3, 2005, which claims the benefit under 35 U.S.C. 119 (a-e) of Italian Application No. TV2004A000128 filed Nov. 10, 2004, which is herein incorporated by reference. 
     BACKGROUND OF THE INVENTION  
     1. Field of the Invention 
     The present invention relates to a method and a control device for automatic systems designed to operate movable barriers, in particular doors, shutters and gates. 
     2. Description of the Related Art 
     In order to comply with existing safety regulations for electric and electronic systems designed to operate and manage movable barriers such as gates, doors and automatic shutters, certain types of safety devices have been widely adopted. Said safety devices are generally composed of infrared photocells and sensing edges (active pressure-sensitive components) which are very common because they result in low production and sales costs and also ensure the necessary level of safety required by the regulations. In particular, these devices must ensure the stoppage as rapidly as possible and the immediate reversal in the direction of movement of the movable barrier in the case where an object, a person or an animal obstructs the normal trajectory thereof or there is an impact. 
     For this purpose the automatic systems for movable barriers are equipped with at least two pairs of photocells (one at a height of 50 cm from the ground and the other at 100 cm) on each side of the access opening, and at least one sensing edge. Since the sensing edge must be fixed to the end of the movable barrier which reaches a fixed end-of-travel point, it is required to provide complex and costly means for connecting together the sensing edge and the electric and electronic system. 
     The connection means according to the state of the art are of the extendable or sliding type which are fixed directly on the inner side of the movable barrier and pass along the whole length of the said barrier before being connected to the electric and electronic system. 
     A generic control device  100  for gates, forming part of the state of the art, is shown in  FIG. 1 . It is essentially composed of an electric motor  102  for operating a barrier  103 , a control unit (not shown, usually incorporated inside the motor) which manages and programs the movements of the gate  103 , means  105  for controlling opening or closing of the gate  103  (remote control devices, key-operated switches, keypads, etc.), sensors and/or warning devices ensuring the safety of the system (photocells  107 , sensing edges  108 ,  208  and flashing lamp  109 ), as well as the necessary electric and electronic means (buses, cables, etc.). 
     The photocells  107  consist of at least one pair for each access/side of the barrier  103  (one pair on the inner side and one pair on the outer side) and are positioned as dose as possible to the moving barrier  103 , in order to prevent the formation of access zones which are not monitored and therefore not safe. Two sensing edges  108  are located on the end of the barrier  103  and on the surface of a fixed body  119  (such as a support column, see  FIG. 1 ) in order to prevent accidental crushing or impacts. 
     A known solution envisages as a connection to the electric/electronic system for a sensing edge, fixed to one end of the sliding barrier, a coiled (spring-type) extendable cable, the ends of which are respectively connected to the sensing edge and to the electric/electronic system. The coiled cable is housed inside a guide tube fixed directly onto the inner side of the movable barrier. 
     Another known solution envisages a container tube housing inside it a cable and a sliding cable-holder chain (similar to a tracked element) having the same function as the coiled cable described above. The ends of the cable are connected respectively to the sensing edge and to the electric/electronic system. 
     All these connection means must be designed in a modular manner so as to be able to be adapted to each type of movable barrier. The manufacture, management and assembly of said connection means is complex and costly. Moreover they are difficult to produce with an aesthetically pleasing form. 
     A third known solution consists in a control device for sliding barriers, composed of a transmitter and a receiver which are used as means for transmitting the status of the sensing edge. The transmitter is fixed to the sliding barrier of the gate and, like the sensing edge, is battery-powered. The receiver is fixed to a stationary part of the gate (a column, wall, etc.) and is powered by the mains. The transmitter, which is directly connected to the sensing edge, transmits a constant and continuous signal (succession of pulses) to the receiver during all the movements and all the pauses in opening or closing of the barrier (continuous transmission). The continuous signal is interpreted by the control unit as an indication that there are no problems and/or obstacles. In the event of pressure against the sensing edge, the transmitter interrupts the transmission of the continuous signal to the receiver, and the control unit interprets this interruption in the signal as being an emergency condition, causing the immediate stoppage and reversal in the movement of the movable barrier. 
     Clearly the efficiency of this device is dependent upon the duration of the batteries powering the first photocell. In fact:
         the control device, and in particular the transmitter, is characterized by a high power consumption since it must transmit a continuous signal in order to avoid waiting times which may result in stoppage of the system;   the technology used to manufacture standard batteries does not guarantee a minimum working period of a few months for the system, unless large-size batteries are used, with the consequent problem of where to house them;   the device does not alert the user when the charging level of the battery is low so that it may be replaced in due time;   the transmitter is able to encode a single type of message (one piece of information), with the risk that the receiver may be disturbed by a signal similar to that emitted by the transmitter (for example by another transmitter positioned incorrectly). This condition may result in the device assuming a “non safety” condition because a possible danger message may be wrongly interpreted or not be detected at all.       

     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a safety device for automatic systems designed to operate movable barriers, which eliminates the disadvantages of the present state of the art. 
     This object is achieved with a method according to the invention, in accordance with the claims below, and the associated devices for implementing it. Said method, in order to control a sliding barrier during the closing and opening movements so as to prevent a dangerous impact with an obstacle or crushing thereof, whereby a dosing edge of the barrier has, positioned along it, one or more sensors connected to a first transceiver able to exchange a signal with a second fixed transceiver in communication with an operating unit which manages the movement of the barrier, comprises the step of defining for said signal a communications protocol consisting of more than two signal configurations. 
     A control device for movable barriers according to the method of the invention allows the transmission of different signals, incorporating a transmission protocol consisting of more than two signal configurations having different coded meanings. The status of a sensor (for example a sensing edge), which is fixed to a movable barrier, is transmitted to the barrier control and operating unit without having to employ complex and costly cable connections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of the invention will emerge more clearly from the following description of a preferred embodiment of the invention, provided purely by way of a non-limiting example of a gate with a sliding barrier, with reference to the accompanying drawings in which: 
         FIG. 1  shows a device according to the state of the art for controlling a movable barrier; 
         FIG. 2  shows a device for controlling a movable barrier, according to the present invention; 
         FIG. 3  shows a block diagram of a receiving photocell; 
         FIG. 4  shows a block diagram of a transmitting photocell; 
         FIGS. 5 ,  6 ,  7 ,  8 ,  9  and  10  show signal configurations. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to  FIG. 2  (reference numbers the same as those in  FIG. 1  indicate similar parts) this shows a control device  21  according to the invention, comprising a pair of photocells  27   a, b . The first photocell  27   a  is a receiving photocell and is situated in the vicinity of an end-of-travel point  29  of the barrier  103 ; the second photocell  27   b  is a transmitting photocell and is positioned at the end of the barrier  103 , close to a sensing edge  108  and connected thereto via traditional electric and electronic means (not shown). Another sensing edge  208  is positioned at the end-of-travel point  29  and is controlled in a known manner by a unit (not shown) controlling the barrier  103 . 
     The photocell  27   b  (see  FIG. 4 ) is essentially composed of wireless means  41  for the transmission of (preferably infrared) pulses and associated driving stages  41  controlled by a microcontroller unit  42  which also processes the information sent by:
         a vibration movement sensor  43  of the known type which detects the “status” of the barrier  103  (dosed or moving);   two comparators  49   a, b  which are configured as window discriminators between two reference voltages V 1  and V 2  used as threshold values and which compare the (voltage) output signal of the sensing edge  108  with said reference voltages. The sensing edge  108  is used to detect the absence of obstacles or an emergency caused by an obstacles coming into contact with the sensing edge  108 ;   a comparator  49   c  which compares the voltage of a power supply battery  46  of the known type with a reference voltage Vref; in this way the microcontroller  42  is able to monitor continuously the charged state of the battery  46 .       

     The photocell  27   a  (see  FIG. 3 ) is essentially composed of a receiving unit  31  which receives and pre-amplifies pulses received from the transmitting photocell  27   b , an amplifier  32  which further amplifies the pulses, a squaring device  33 , a microcontroller  34  which interprets the signal received and exchanges control signals with the control unit via a general connection output  35  (of the known type), with a display component  36  able to display status or emergency messages, and with configuration components  37  of the known type able to define the ideal set-up according to the specific requirements of the user or the different applications. The output of the amplifier  32  is squared by the squaring device  33  and sent to a digital input of the microcontroller  34 . By means of this input the microcontroller  34  is able to detect the time periods which lapse between one pulse and the next. 
     The operation of the control device  21  is characterized by a protocol for transmission between the two photocells  27   a,b  which has signal configurations (frames) repeated with a variable period depending on whether the device is in “fast” mode (for example with a period=14.5 ms) or in “slow” mode (for example with a period=463 ms). These preferred signal configurations are visible in  FIGS. 5-10 . 
     Switching between the “fast” mode and “slow” mode is regulated by the status of the movement sensor  43  which enables two particularly innovative features to be obtained:
         by means of the microcontroller  42  of the transmitting photocell  27   b , frames with a slow repetition (“slow” mode) when the barrier  103  is stationary and fast repetition (“fast” mode) when the barrier  103  is moving are sent to the receiving photocell  27   a ; therefore, constant communication is maintained between transmitting photocell  27   b  and receiving photocell  27   a , independently of the movement status of the barrier  103 : from the point of view of safety the control device  21  of the barrier  103  is extremely reliable;   detection of the movement status of the barrier  103  by means of the movement sensor  43  results in an increase in the working life of the battery  46 , which, in the case of commercial batteries, may be as long as 10 years; in fact, by switching to “slow” mode when the barrier  103  is stationary, namely to a slower transmission frequency of the transmitting photocell  27   b , the power consumption of the latter is greatly reduced, whilst increasing the working life of the battery  46 .       

     The signal configurations are composed as follows:
         two start bits  80 ,  81 , for example with a duration of 10 μs and an interval of 250 μs, which allow the receiving photocell  27   a , in particular the microcontroller  34 , to synchronize with the start of the transmitted frame;   a bit  85 , for example with a duration of 10 μs and interval of 550 μs from the bit  80 , which signals when the sensing edge is in the non-activation state, i.e. when there is no obstacle (see  FIG. 5 );   a bit  86 , for example with a duration of 10 μs and interval of 650 μs from the bit  80 , which signals when the sensing edge is in the active state, i.e. when there is contact with an obstacle (see  FIG. 6 );   a bit  87 , for example with a duration of 10 μs and interval of 750 μs from the bit  80 , for signalling to the receiving photocell  27   a  the switching to “slow” mode (see  FIG. 7 );   a bit  88 , for example with a duration of 10 its and interval of 850 μs from the bit  80 , which signals when the power of the battery  46  is low (see  FIG. 8 ).       

     The bits  85 ,  86 ,  87 ,  88  are transmitted only when the event associated with them occurs. Therefore, there are in total four different signals which may be transmitted, however, with a different period, depending on the “slow” or “fast” transmission mode. For the sake of simplicity of the description, the signals shown in  FIGS. 5 to 8  are defined as type A, B, C and D signals, respectively. 
     The particular feature of communication consisting of a signal which is repeated at non-constant, but known intervals allows the receiving photocell  27   a  to recognize the signal of the transmitting photocell  27   b  also when stray signals are present. The receiving photocell  27   a  has the fundamental feature of repeating internally the exact time intervals with which the transmitting photocell  27   b  sends the frames. In other words the receiving photocell  27   a  locks to the transmitting photocell  27   b . When the receiving photocell  27   a  is not locked, it remains on standby until it recognizes the signal time patterns of the transmitting photocell  27   b  and then starts to repeat the exact transmission sequence. In this way the receiving photocell  27   a  regards as valid the frames which reproduce the sequence (with a suitable allowable variation) and regards as being not valid those frames which are out of sequence. If the non-valid frames are fairly sporadic events then these will simply be ignored, otherwise the receiving photocell  27   a  advantageously sets the device  21  to the maximum safety condition (system blocked). 
     If necessary, it is possible to use further disturbance rejection methods, for example by modifying the period which characterizes the “slow” mode and/or “fast” mode, varying it slightly between one frame and the next. For example, for the “slow” mode, the sequence of transmission periods could cyclically be 493 ms, 494 ms, 495 ms, 493 ms, 494 ms, 495 ms and so on. 
     The control device  21  functions in the following manner during the various operating phases:
         Status of barrier  103  dosed or open, but stationary. The microcontroller  42  processes the signal from the movement sensor  43  and the sensing edge  108 . Being in a completely safe condition, it sends to the receiving photocell  27   a  a type A signal in “slow” mode;   Opening or dosing of the barrier  103 . Following a closing or opening command sent to the control unit, the electric motor  102  starts to move the barrier  103 , the movement of which instantly excites the movement sensor  43  which in turn sends a “movement” signal to the unit  42 . The latter enters into “fast” mode and again sends to the receiving photocell  27   a , via the transmission means  41 , a type A signal. The type A signal in “fast” mode therefore indicates the moving condition of the barrier  103 . At the same time the control unit activates the flashing lamp  109  which signals the movement, using a known procedure. At the end of movement of the barrier  103 , the unit  42  detects the absence of a signal from the movement sensor  43  and absence of a signal from the sensing edge  108  and therefore the barrier  103  is closed or open, but in any case stationary. After a predefined brief period where there is no movement of the barrier  103 , with continued transmission of a type A signal in the “fast” mode, the unit  42  decides to switch to the “slow” transmission mode and informs the receiving photocell  27   a  of this by sending the type C signal.       

     Said “slow” transmission state, in which the type A signal is sent, lasts until a new movement signal is received from the movement sensor  43 .
         Detection of an emergency. During movement of the barrier  103 —hence while the photocell  27   b  is transmitting a type A signal in “fast” mode—it may happen that the sensing edge  108  detects an obstacle. The unit  42  detects the variation in “status” of the sensing edge  108 , by means of the comparators  49   a,b , and sends an emergency signal to the receiving photocell  27   a , using the type B signal configuration in “fast” mode. The microcontroller  34  receives this signal and orders the control unit to stop immediately and reverse the movement of the barrier  103 .       

     Obviously, the pair of photocells  27   a  and  27   b , in addition to transmitting the signals described above, function with the methods according to the state of the art, namely that if an object, person or animal passes through the beam thereof, the movable barrier  103  is stopped and its movement reversed. In fact, the receiving photocell  27   a  interprets the absence of signal from the transmitting photocell  27   b  as indicating the presence of an obstacle.
         Monitoring of the battery  46 . Despite the low power consumption of the batteries achieved as a result of the “slow” transmission mode, it is envisaged providing a signal configuration, specifically a type D signal, which is transmitted by the transmitting photocell  27   b  to the photocell  27   a  and which signals that the charge of the battery  46  is very low. In this case the microcontroller  34  will activate the display means  36  so as to display the status of the battery  46  (flashing light, signalling LED, etc.) and alert the user.       

     It is also clear that, during operation of the control device  21 , it is possible to use one or more photocells  107  forming part of the known art, independently of operation of the invention. 
     The invention ensures an operating autonomy equivalent to the average working life calculated for all the components which form the control device  21 , without the need for continuous replacement of the batteries  46 . In this way unnecessary costs for assembling awkward and costly accessories, requiring the intervention of specialized personnel, are avoided. 
     The invention may be subject to many variations. For example, transmission between the photocells  27   a,b  may occur via radio or some other wireless system. Instead of the sensing edge  43  and/or together therewith it is possible to use other types of sensors (proximity sensors, ultrasound sensors, etc.). The microcontrollers  34 ,  42  may be replaced by any data processing unit or suitable circuit, while the photocells  27   a,b  may both be equipped with transceivers such as to obtain two-way data communication. This may be useful, for example, in the case where the barrier  103  has, as already mentioned, other sensors or devices in addition to the sensing edge  43  and information is to be received from the photocell  27   a  after data has been sent to it via the photocell  27   b , for example regarding the state of a lock of the barrier  103 , an access combination, etc. Moreover, the fixed transceiver may also be positioned far from the barrier  103 , for example in the case of remote and centralized control of many movable barriers, and may be used to transmit to the control unit the status of sensors which are not positioned on the barrier  103 . 
     In place of the battery  46  it would also be possible to use, for example, a solar cell power supply. 
     The movement sensor  43  could also not be located on the shutting element of the barrier  103 , as in the case of a Doppler sensor. These and other variants are in any case included within the scope of protection of the following claims.