WO1993004255A1

WO1993004255A1 - Guard system for automatic doors

Info

Publication number: WO1993004255A1
Application number: PCT/BE1992/000032
Authority: WO
Inventors: Tuyen Tran; Emmanuel Eubelen
Original assignee: Belgian Electronic Research S.A.
Priority date: 1991-08-14
Filing date: 1992-08-11
Publication date: 1993-03-04
Also published as: ATE150514T1; BE1005260A6; DE69218391D1; EP0552338B1; DE69218391T2; EP0552338A1

Abstract

At least one face of one or each leaf of an automatic door has an obstacle detector (20) consisting of a movement detector arranged to generate a signal proportional to the relative movement of an obstacle in the spatial detection field of the detector with respect to the corresponding door leaf. A controller is placed to acquire the detection signal generated by the detector for each door leaf and produce a set point signal for door automation, said set point signal representing the relative movement of the obstacle having the slowest movement with respect to door leaf movement. Each movement detector consists advantageously of a Doppler detector which produces a detection signal having a frequency component porportional to the speed of a surface or obstacle moving relatively to the door leaf.

Description

PROTECTION SYSTEM FOR AUTOMATIC DOORS

The present invention relates to an electronic system for optimal protection of persons within the operating range of an automatic door.

State of the art

A system of this kind is intended to ensure the protection of people moving or immobilizing themselves in the space swept by the movable part of an automatic door, for example a revolving door. In order to avoid any contact between, the user and the mobile equipment of this kind of automatic door, it is important to equip it with a system for detecting people evolving or present in their field of action, in order to give the automatic control, the instructions necessary to avoid contact which may prove to be damaging.

Electronic presence detectors are known, comprising a transmitter for emitting radiation or waves, and a receiver for picking up reflected diffuse radiation or waves reflected by an obstacle, located in the covered spatial field so as to produce a signal detection function of the reflected intensity.

These detectors, conventionally installed on the mobile part of an automatic revolving door, can monitor the space swept by the door during its movement, and provide a signal when a person or object present in its radius of action. This signal is by nature an all or nothing signal and, depending on the particular application that one wants to make of it, allows either to slow down the movement of the door, or to stop it. This does not take into account the relative speed or the relative distance between the door and the detected obstacle.

The unique protective action generated by this type of presence detector can in certain cases hamper the efficient operation of the drum holder, which can then be constantly stopped or slowed down in its rotational movement due to the very irregular passage of pedestrians within its radius of action. All-or-nothing detection is only part of the solution to the protection problem.

On the other hand, it is well known that certain optoelectronic presence detectors are particularly sensitive to the nature, the color and the reflecting power of the background which they cover. During the movement of the door to which it is fixed, this kind of detector sees its useful signal constantly varying, depending on the characteristics of the background; according to the set trigger threshold, the slightest unforeseen disturbance leads to an unwanted detection, and therefore the slowdown or untimely stopping of the door. The more sensitive the detector - which is generally desired so that the protection it provides in front of the moving part of the door extends as close to the ground as possible - the more frequent the appearance of parasitic detection.

A method, based on the analysis of the signal signature as a function of the angular position occupied by the movable part of the door, would make it possible to hold account of the irregular background structure. However, an occasional modification would not be taken into account and would cause untimely detection. In addition, this method also does not take into account the relative movement (speed or relative distance.) Between the door and the obstacle detected.

Finally, other types of presence detectors, based on the measurement of the propagation time of ultrasonic waves, have some of the drawbacks mentioned above, notably the unwanted detections due to the modification of the sensitivity of the detector in function of climatic conditions (temperature, humidity), sensitivity to drafts, situation particularly aggravated by the mixing of indoor and outdoor air carried out by the drum carrier during its rotation, sensitivity to vibrations and to some ambient noise. These detectors also provide all or nothing information, controlling either the deceleration or the stop of. the door, without ever taking into account, the relative movement between the por¬ te and the obstacle detected.

In summary, the known detection techniques commonly used to protect people moving in an automatic drum carrier suffer from the following disadvantages:

1 °) The detectors used are presence detectors, which give an all or nothing signal to the automatic control mechanism of the door so that the latter can only slow down or stop, regardless of the speed. relative or the relative distance between the door and the obstacle. This mode of action on the door is not optimal: stopping is a nuisance for potential users in other areas of the door. No doubt the slowdown moderates this nuisance, but it nonetheless constitutes a danger for the user who may have fallen into the sector where the detection took place. In either case, the passage is obstructed and the comfort of use of the drum holder is reduced.

2) The presence detectors used are affected by imperfections inherent in their technology, causing parasitic detections, which reduces the efficiency of the door. Among these imperfections, we should highlight the following:

Infrared detectors behave according to the characteristics of the background they cover: nature, color and reflective power; they may be sensitive to external light radiation, and their performance may be reduced due to the permanent passage between the external environment and the internal environment, resulting in differences in luminosity.

The ultrasonic detectors have a behavior which is a function of the climatic conditions: temperature, humidity, displacement of air, and their performances can be reduced due to the permanent passage between the external medium and the internal medium, causing variations in these conditions. and a permanent air circulation. In addition, these detectors are sensitive to vibrations and certain ambient noise. Statement of the invention

The object of the present invention is to remedy the drawbacks mentioned above of the known protection systems for automatic doors.

This objective is achieved according to the invention by a protection system for an automatic door, comprising an obstacle detector fixed on at least one face of each leaf, said obstacle detector comprising a transmitter for emitting radiation or waves in a spatial detection field, a receiver for picking up radiation or reflected waves, and a detection circuit for converting the radiation or reflected waves into an electrical detection signal used to control the automation of the automatic door.

According to a first aspect of the invention, each obstacle detector is a detector arranged to generate a signal proportional to the relative movement of a surface or an obstacle in the spatial detection field of the detector with respect to to the corresponding leaf, and the system further comprises a controller arranged to acquire the detection signal generated by the detector of each leaf and produce a setpoint signal for the automation of the door, the said signal setpoint being determined as a function of the relative movement of the obstacle animated by the slowest movement relative to the movement of the leaves.

Each detector can for example be arranged to produce a detection signal proportional to the relative speed of a surface or an obstacle with respect to the corresponding leaf or a detection signal proportional to the distance between an obstacle and the leaf.

Thanks to the setpoint signal which it produces as a function of the relative movement of an obstacle with respect to the door, the controller ensures effective servo-control of the door according to the movement of the user.

The invention can not only be used for a revolving door but also for the protection of persons in front of an automatic pivoting door, generally consisting of a single motorized leaf allowing the door to rotate through an angle practically equal to 90 °.

In the case of a revolving door, the controller makes it possible, in accordance with another aspect of the invention, to adapt the speed of rotation of the door to the movement of the user who moves most slowly in a of its sectors, thus optimizing the functioning of the door.

Since this process of controlling the speed of the revolving door is based on a measurement of relative movement in different sectors of the door, it is useful for the detectors operating in the different sectors to be adjusted identically.

According to another aspect, the invention therefore proposes a method for adjusting the detectors controlling a revolving door, according to which a predetermined speed of rotation is communicated to the door, a signal of success is applied to each means of comparison initial predetermined reference, then we do gradually and successively decrease each of said reference signals until a measurement signal is detected by the controller, and then the reference signal of each comparison means which controls controls is increased by a first identical increment the relative movement of a reference surface, and finally the reference signal is increased by a second identical increment, greater than the first increment, of each comparison means which controls the relative movement of an obstacle entering the detection field.

When the detectors fitted to the different leaves are set identically, it is possible to organize the controller so that it compares the signals of. detection produced by the various door detectors, and issue an alert signal when the detection signals in the absence of an intruding obstacle (no-load operation) are not all the same or when a predetermined number of they are different from the others. The invention thus advantageously allows automatic self-monitoring of the protection system itself.

The invention is explained in more detail below with the aid of the accompanying drawings.

Brief description of the drawings

Figure 1 is a schematic plan view of a four-leaf drum holder.

FIGS. 2A-2D illustrate the different stages of the progression of a pedestrian during his passage through an automatic drum carrier. Figures 3 and 4 schematically show an automatic drum holder equipped with a conventional protection device (optoelectronic or ultrasonic presence detector). FIG. 5 represents a variant of the device illustrated in FIG. 3.

FIG. 6 illustrates a method of detection by barrier, ultrasound or infrared.

Figures 7 and 8 schematically show an automatic drum holder equipped with a protection device according to the invention.

FIG. 9 is a block diagram of the protection system according to the invention.

FIGS. 10 and 11 show a variant of the device according to the invention, offering better longitudinal coverage.

Figures 12 and 13 show some waveforms associated with the process of regulating the speed of the drum carrier according to the invention. Figure 14 is a block diagram of the protection system of Figure 10 incorporating an automatic adjustment system according to a second aspect of the invention.

Description of embodiments of the invention

The automatic revolving door, known per se, shown in FIG. 1, consists for example of four movable leaves, denoted 1, which are integral with a central axis shown in 2. An appropriate motorization (not shown) allows to drive the axis 2 and the leaves 1 according to a generally uniform rotational movement represented by the curvilinear arrow. A fixed and curved envelope 3, 3 'partially surrounds the mobile drum, providing access zones 4 and 5. The assembly as described is generally constructed symmetrically with respect to a wall or a partition 6, 6 ′, conventionally delimiting an outside area 7 and an inside area 8.

It is clear that the number of leaves can be different from four, and that. the door can be fitted with a mechanism that drives the leaves in a non-circular movement. There are mechanisms driving the leaves partially in rotation and partially in translation.

In FIG. 2, the black square denoted 9 symbolizes a pedestrian wishing to pass for example from the outside 7 towards the inside 8, who comes up to the access zone 4 (entrance) and enters there, when, the space left for example by the leaves 1a and 1b is sufficient (FIG. 2A). By accompanying the movement of rotation of the door (FIG. 2B), it is engaged in the revolving door, between the leaves 1a and 1b. In FIG. 2C, the pedestrian is in view of the access zone 5 (exit) which emerges as a function of the rotation of the door. In Figure 2D, the pedestrian leaves the revolving door by the exit zone 5.

It is understood that, during its progression, a pedestrian who stops or slows down may very well be caught and struck by the leaf which follows it (for example, the leaf lb, FIGS. 2B and 2C). In many cases, this. shock between mobile leaf and pedestrian is harmless: it is enough for the pedestrian to recover from. the speed and deviates from the leaf concerned. However, one can imagine the risk run by a pedestrian who fell to the ground after being struck by a leaf that was still moving. In any case, the comfort of using a automatic revolving door means that the user is never struck by a movable leaf, which amounts to ensuring the safety of people.

In order to avoid any risk of impact between the moving part and the user, or even any accident, the automatic revolving door should be equipped with a detection device capable of giving the automation controlling the door the instructions to avoid this kind of 'accident.

Certain presence detectors are conventionally used for this purpose. Figures 3 and 4 schematically show one. automatic drum holder with four leaves 1 fitted with four active infrared presence detectors 10. These are fixed to the upper part of each mobile leaf, and comprise, as is well known, a transmitter for emitting radiation infrared from top to bottom, a receiver for picking up reflected diffuse radiation in order to produce a detection signal which is a function of the intensity reflected, therefore of the presence or absence of an obstacle.

The detection lobe 100 has substantially the shape of a pyramid with a rectangular base, relatively narrow so as not to cover too large a portion of the sector comprised between two consecutive leaves, but sufficiently large to provide protection in front of the leaf. that he protects. The portion of space covered by the detection lobe does not extend to the ground, however: it has a dead zone, shown in dotted lines in FIG. 3, area in which no detection can take place in order to '' avoid taking into account background irregularities. During the rotation of the door and the progress of the pedestrian, a detection takes place as soon as the latter, either for having slowed down, or for having stopped, enters the detection lobe of the sensor. Conventionally, the detection signal produces either the stopping of the door, or its slowing down, regardless of the relative speed or the relative distance between the door and the detected obstacle.

In periods of heavy traffic, several pedestrians may be present simultaneously in the consecutive sectors of the door; stopping the door due to detection in a sector constitutes a nuisance for users present in the other sectors of the door. On the other hand, if detection in one sector causes the door to slow down, this makes it possible to reduce the nuisance for users in other sectors, to the detriment of security in the sector where detection has taken place: Indeed, if the detection occurred following a fall of a user, the simple slowing down of the door can cause a shock between the leaf and the user fallen on the ground.

Although having a dead zone on the ground, the detector can however be influenced by the presence on the ground of objects having a strong contrast with respect to the background; this can lead to parasitic detections, and therefore to a reduction in the efficiency of the system.

The mode. of. protection illustrated in Figure 3 is subject to some variants characterized by different lobe shapes, a different sensor position (horizontally at any point on the upper part of the door, or even vertically or obliquely, on the central axis or the opposite upright or even halfway up). A similar protection mode, based on ultrasonic detection is also possible. It generally involves a cone-shaped lobe, the diameter of the circular base of which is generally reduced. In all these cases, the presence detection involves a simple action on the movement of the door: slowing down or stopping, with the drawbacks mentioned above. It is clear that this completely usual mode of protection does not allow the relative movement between the door and the obstacle to be taken into account.

FIG. 5 illustrates another detection method conventionally used. This consists, by van¬ tail, of a longitudinal detector fixed horizontally halfway up the leaf. FIG. 5 shows, for example, the detector of leaf 1. The detection can be, infrared or ultrasonic. : the detection lobe 100 is horizontal or almost horizontal, and extends in a space very close to the door. It is in fact a somewhat particular variant of the cases cited above, which has the advantage of better immunity to parasitic detections due to ground irregularities because the detection lobe is not directed to the ground. However, in the infrared version, the detector can be affected by external parasitic light radiation, while in the ultrasound version, many of the drawbacks mentioned affect the detector. On the other hand, the covered area is quite small, and children or fallen people cannot be detected. This detection mode, in this case also, provides information all or nothing, causing only a single action on the door, without taking into account its relative movement.

In the figure. 6 we can see one. another conventional variant in which an ultrasonic or infrared beam, coming from a detector 10 placed in the lower part of the axis of rotation 2, covers a field horizontally in front of the lower part of the leaf from the axis of rotation 2 until substantially at the opposite edge of the leaf, thus constituting a barrier almost at ground level. As soon as the barrier is intercepted by a person during the rotation of the door and this regardless of the relative speed or the relative distance between the door and the obstacle, an all or nothing signal is given and the door slows down or stops. Some of the disadvantages mentioned in this. above and inherent in the technology used (infrared or ultrasonic) also affect the system. It is clear that the drawings illustrate only one of the detectors, and that other similar detectors are fitted to the other leaves of. the door.

The invention provides a solution to the problems stated above. Figures 7 and 8 show schematically a drum holder equipped with a protection system according to the invention, in a preferred embodiment. The protection system includes a leaf detector. In FIG. 7, only a detector 20 is seen, for example fixed to the upper part of the leaf 1 and directing its detection lobe 200 from top to bottom. According to the invention, the detectors 20 are preferably detectors capable of measuring the relative speed or the relative distance between a being or object occurring in their field of action and the door. Detectors are for example Doppler detectors (known per se), based on microwave technology but other technologies are applicable, such as for example ultrasound.

The system also includes a controller for carrying out the acquisition of the signals supplied by the detectors equipping the revolving door, calculating the enslavement rating thereof and optionally ensuring the self-monitoring of the system. The controller is shown in FIG. 9 which is a block diagram of the complete protection system according to the invention.

As is known per se, each detector includes a transmitter circuit 12 to generate a microwave signal which is radiated in space by an antenna shown at 11. This, as is well known, can be made up of a horn, a parabola, a radiating waveguide or any other radiating element known to those skilled in the art. Any relative moving obstacle in the field of action of the detector in a sector of the door reflects part of the incident wave and the reflected wave is picked up by the antenna and mixed with the incident wave thanks to a mixer present. in a receiver circuit 13. Consequently, and due to the Doppler effect, a low frequency signal is available at the output of the receiver 13. The frequency of the Doppler signal is proportional to the relative speed of the obstacle detected and its amplitude is proportional to the size and proximity of the detected obstacle.

The detection signal from each receiver 13 is applied to an amplification and filtering circuit 14, the output of which is for example connected to the inputs of a digitization cell 15. The latter mainly comprises two comparators, known per se, which use the information contained in the amplitude of the detection signal.

The first comparator 15a has a comparison threshold denoted + fixed for detecting the low amplitude signal corresponding to the relative movement of the ground relative to the detector fixed on the leaf. At the output of the comparator 15a, there appears a digitized square wave signal, such as. shown in 160.

When a person or an object of sufficient mass comes before the detector and is animated relative to the latter by a relative speed, it generates a Doppler signal of amplitude significantly greater than the signal coming from the reflected wave. because of its size and proximity.

The second comparator 15b has a comparison threshold denoted + fixed to detect a signal of greater amplitude than the first comparator: it therefore switches only when a person or an object has been detected. At the output of the comparator 15b, a digitized square wave signal appears, as shown in 170, only during the periods of detection of a person or an object.

As can be seen, each of the detectors 20 delivers at its output two digital signals containing information of a frequency nature which, for one of the signals, is proportional to the relative speed of travel of the ground relative to the detector ( leaf) in the absence of detection of an obstacle, and for the other, at the relative speed of the obstacle with respect to the detector 20 (leaf).

Before going further in the description of the other characteristics of the system according to the invention, it should be noted that a motion detector as provided in accordance with the invention is not affected by the drawbacks mentioned in the description conventional solutions: they are not influenced by the structure of the background they cover (nature, color and to some extent reflective power) they are not sensitive to light radiation nor to the differences in luminosity between the external and internal zones of the revolving door, and they do not have a behavior affected by the climatic conditions mentioned above neither by the air currents, nor by the ambient noises.

It should also be noted that the detectors used can occupy any position on each leaf of the revolving door, provided that this location allows them to measure the speed, relating obstacles to be detected.

Note also that an advantageous variant of the in¬ vention would be to equip the detectors with an antenna formed by a radiating waveguide, known per se, this. which would provide longitudinal coverage over the entire width of the leaf, as shown in Figures 10 and 11.

Unlike the embodiment illustrated in FIGS. 7 and 8 where the detectors radiate in a conical-shaped detection lobe with an elliptical base, the detectors shown in FIG. 10 radiate in a detection lobe 200 having the shape of a narrow brush extending over the entire width of the detector (FIG. 11). This variant advantageously reinforces the efficiency of detection.

The signals 160 and 170 from each detector 20 are routed through the lines 16 and 17 to the controller 30. The latter is for example constituted by an architecture circuit around a microprocessor which comprises the conventional elements or peripherals. Appropriate software allows the controller to perform the following functions:

- calculation of a speed setpoint to be transmitted to the door motor control;

- automatic system adjustment;

- system self-monitoring.

In order to optimize the operation of the revolving door, it is advantageous to regulate the speed of rotation of the latter as a function of the obstacles appearing in front of the leaves, while allowing the door to stop when a dangerous situation arises.

According to the invention, the controller 30 performs several tasks:

- It periodically acquires the input signals 160 giving the speed of. the door in the absence of user and stores this value in memory;

- It continuously scans the signals 170 giving the relative speed between a detected user and the door; - it detects the appearance of a Doppler frequency in one of the signals 170, which means that a user has entered the detection lobe of one of the detectors, therefore that it is driven by a relative speed tending to cause it to come into contact with the leaf that follows it;

- It calculates the speed setpoint to be communicated to the door control to make the Doppler frequency measured towards that of signals 170 where the risk of collision is greatest tend to zero.

The speed setpoint is communicated to the door control by means of a connection shown in 19 which can be of any type: for example analog, serial, parallel, or any other known means of communication.

A control circuit at the door control level can act on the speed of the motor, according to the setpoint calculated by the controller 30, in order to restore satisfactory conditions of use, namely a rotation speed adapted to the most slow of the users present in the drum holder at a determined time.

When, following the slowing down of the door, the relative speed measured at the detector tends towards zero, this means either that the slowest user is moving in synchronism with the door, or that he has picked up speed and is found outside the detection lobe of the detector fixed on the leaf which precedes it. This situation is obviously harmless to the user.

On the other hand, when the door slowdown instruction does not give the expected result, namely the cancellation of the relative speed, measured by the detector, this means that the detected obstacle is fixed or that it is moving in the opposite direction to the rotation of the door. In this case, the controller must order the immediate stop of the door in order to prevent the obstacle from coming into contact with the leaf.

The. regulation process can be continuous or dis¬ continuous. Figures 12 and 13 show some waveforms illustrating a discontinuous regulation process according to the invention and which constitutes one example of application among others possible. The waveform denoted Vrel corresponds to the relative speed between, the obstacle detected and the leaf, calculated by the microprocessor of the controller 30, from one of the frequency channels 170. The waveform denoted CF is for example a discontinuous braking setpoint, active in the high state denoted 1. The waveform denoted V represents the speed of the door. All these curves are referenced with respect to the same time axis.

FIG. 12 illustrates the case where a user is driven by a speed, a displacement slightly lower than the tangential speed of the door. It is noted that from the instant t0, the relative speed is detected on one of the measurement channels as soon as the user enters the detection lobe of the leaf which precedes it. At the instant t1, the controller 30 sends a braking instruction CF to the automatic control of the door. This automatism begins to act at the instant tl + ε, which results in a. reduction of the speed V of the door, and in the case considered here, to one. decrease in the relative speed measured. Vrel. In the example illustrated, the duration of braking is for example 100 milliseconds. The brake setpoint CF returns to the low state at time t2. During the following time interval t2- t3, which for example has a duration of 100 milliseconds, the controller acquires the relative speed and if this is not zero, it sends a second time a brake setpoint at the door control automation. The setpoint is in the high state during the time interval t3-t4 of 100 milliseconds for example. From time t3 + ε, the braking effect is such that the speed V of the door decreases again and, in the case considered, the measured relative speed Vrel also decreases. The process described above is repeated, for example once again. At time t6, ie 500 milliseconds after the start of the regulation phase, the controller notices that the relative speed Vrel has been canceled, either because the user is moving in synchronism with the door. , or because it is now outside the detection lobe. The speed of the door is maintained at its new value for 500 milliseconds for example, after which the controller can restore the door to its initial speed of rotation.

FIG. 13 illustrates the case where a user is stopped in a sector of the revolving door. The process proceeds as described above. However, at time t6 (for example 500 milliseconds after the start of the regulation process), the controller notices that the relative speed of the obstacle detected relative to the leaf is far from being canceled out, and it then commands the immediate stop of the door.

it should be noted that the stopped obstacle leads to a relative speed measurement equal to the relative speed of travel of the ground relative to the leaf, which can be used by the controller 30.

It is easy to see that the use of Doppler detectors fitted with a displacement direction discriminator makes it possible to detect whether the obstacle is moving in the direction of rotation of the door or in the opposite direction, which allows a even finer regulation than the process described above.

It is clear that other types of detectors can be used, for example, infrared or ultrasonic detectors, but with the drawbacks inherent in their technology as explained above.

In the particular case where the detector is placed horizontally at mid-height of the leaf or on the lower transom of the leaf, or even vertically in the lower part of the leaf, it is possible to use a distance measuring detector ( for example ultrasonic) which emits and receives in a horizontal plane or in a vertical plane, and which calculates the propagation time between the emitted wave and the reflected wave, which, as is well known, amounts to measuring the distance relative between the detector (therefore the leaf) and the obstacle located in front of the leaf.

The speed setpoint calculated by the controller 30 and communicated to the automatic control of the revolving door must allow the process of regula¬ tion to maintain between the obstacle and the door a distance greater than a given value. This process of. Regulation, continuous or discontinuous, is very similar to the process described above and should be considered as included in the present invention. Other types of detectors can be used for distance measurement as described, and in particular infrared triangulation detectors.

It is also evident that the distance measurement is inapplicable when the detector is fixed to the upper part of the leaf and directs its detection lobe from top to bottom. In this case, the distance measured also depends on the size of the obstacle detected, and not only on its position relative to the door, which is not the case when the measurement is made. in a horizontal plane.

As can be seen, the regulation process according to the invention makes it possible, thanks to the speed setpoint calculated by the controller 30, to adapt the speed of the drum carrier to the user who moves most slowly in one of its sectors and thus optimize their operation.

The device according to the invention is a fortiori capable of controlling only the stopping of the door or its slowdown at a predetermined speed just as in conventional known systems.

On the other hand, the invention can advantageously be used for the protection of persons in front of an automatic pivoting door, generally consisting of a single motorized leaf allowing the door to rotate through an angle practically equal to 90 °. This embodiment can be considered as a particular case of application of the invention, although the control of the pivoting door is not necessary in this case. Another aspect of the invention relates to the automatic adjustment of the detectors. Since the whole process of speed regulation of the revolving door is based on the measurement of the relative speed in different sectors of the door, it is advantageous that the detectors controlling the different sectors of the door are set identically. Like each detector, as described above, provides two measurement signals, the adjustment of the detectors equipping an automatic drum holder represents a tedious, but also particularly delicate work. It is certain that the installers do not necessarily have the means to control the quality of the adjustment on site, or even the skills required to do so. The invention allows, although this is not an absolute necessity, an automatic adjustment process of the detectors equipping a drum holder. The operation will be understood by referring to FIG. 14. After installation and connection of the detectors, the installer puts the revolving door into service and starts the initial adjustment phase by pushing, for example, on a button -pusher acting on an input line 31 of the microprocessor. The door is animated, with a uniform rotational movement, at a speed predetermined by use.

During this rotation, the controller 30 proceeds to the successive acquisition of the signals 160, 170 by acting progressively on the reference voltage of each of the comparators 15a and 15b. To this end, the reference voltage of the comparators 15a and 15b is supplied by the controller 30 by analog outputs 32, 33 coming from digital / analog converters (DAC). The process starts from an initial setting for which the reference voltage of the comparators 15a and 15b is for example maximum and for which no frequency can be detected on the signals 160 and 170 given the large switching threshold initially imposed on the comparators and the low amplitude of the Doppler signal corresponding to the relative speed of travel of the ground with respect to the respective leaves. The controller 30 progressively and successively decreases the reference voltage applied to the comparators 15a and 15b until a Doppler frequency is detected on each signal 160, 170. The controller 30 then increases by a small increment identi¬ as the reference voltage of the comparators 15a which give the relative speed of travel of the ground or of a reference surface with respect to the leaves, in order to take account of any drifts and to provide tolerance in the measurement of this relative speed. It then proceeds to the same operation for the other comparators 15b which give the relative speed of the obstacle detected relative to the leaves, but with a larger identical increment, fixed by experience. At the end of this adjustment sequence, each of the detectors is adjusted identically, a condition necessary for optimal operation.

Other methods of adjusting the detectors are possible, for example the automatic gain adjustment of each of the amplifiers 14 while the reference voltages, comparators 15a and 15b are fixed at a precise value determined beforehand. This adjustment process involves modifying the values of the feedback resistors of the amplifiers, which can be done by switching a set of resistances by means of analog switches pilo¬ ted by the microprocessor via output lines. It is obvious that an automatic detector adjustment process can, according to the invention, be applied to other types of detectors.

A final aspect of the invention relates to the self-monitoring of the system. Since the protection system must stop the revolving door in the event of danger, it is sometimes essential, for safety reasons, to use self-monitoring detectors in its environment. As the detectors fitted to the leaves of an automatic revolving door can be adjusted identically, it is simple to apply the majority rule to them in order to determine whether their operation is correct. Indeed, the rotation of the drum holder is generally controlled by approach detectors located on either side of the accesses 4 and 5 when a user comes up to them. It is easily understood that, during the idle rotation of the door, the controller 30 can check whether the speeds given by each of the detection signals 160 are identical. Otherwise, it means that one or more detectors are faulty, which must be reported immediately. It goes without saying that the software residing in the controller 30 must be written in compliance with the standards concerning self-monitoring systems controlled by microprocessor. It is also clear that the self-monitoring as described above can be applied to any type of detector usable in a protection system for an automatic drum carrier.

Finally, the block diagrams of Figures 9 and 14 are given by way of example. Certain inter- born with the detectors can perfectly be carried out within the controller 30 itself, in particular all the functions linked to the comparators 15a and 15b which can be provided in digital technology, by means of the direct connection of the output of the amplifiers-filters to analog / digital converter inputs to be provided on board the controller. In this case, the automatic adjustment function no longer requires digital / analog converters at the output, since the whole process described above can be carried out entirely by software.

Other modes of processing the Doppler signal, previously amplified and made available at the inputs of each, analog / digital converter of the controller 30, are possible and do not necessarily involve the digitization of this Doppler signal at l using two comparators 15a and 15b, as described above, or their software equivalent.

One thinks in particular of the digital processing of the Doppler signal, aiming at the calculation of the frequency and the amplitude thereof, thanks to an algorithm known per se, and at the comparison of these calculated values with previously stored references, said references corresponding to typical operations of the system: unladen, in the presence of an obstacle, etc.

The recognition of an obstacle and the calculation of its relative speed could advantageously be carried out according to the variant consisting in comparing time samples of the detection signal with reference models previously stored, said reference models corresponding to typical operations system issues: no-load operation, operation in the presence of an obstacle, etc. All techniques of signal shape recognition can be applied, including fuzzy logic techniques.

Claims

1. Protection system for an automatic door comprising at least one leaf, which protection system comprises an obstacle detector fixed on at least one face of each leaf, said obstacle detector comprising a transmitter for emitting ra¬ diations or waves in a spatial detection field, a receiver for picking up radiation or reflected waves, and a detection circuit for converting radiation or reflected waves into an electrical detection signal used to control the automation of the automatic door, characterized in that each obstacle detector is a detector (20) arranged to generate a signal proportional to the relative movement of a surface or an obstacle, in the spatial detection field of the detector by relative to the corresponding leaf, and in that the system further comprises a controller (30) arranged to acquire the detection signal generated by the detector of each va ntail and produce a setpoint signal for the door automation, said setpoint signal being determined as a function of the relative movement of the obstacle animated by the slowest movement with respect to the movement of the leaves.

2. System according to claim 1, characterized in that each detector (20) produces a detection signal proportional to the relative speed of a surface or an obstacle relative to the corresponding leaf.

3. System according to claim 2, characterized in that each detector (20) consists of a Doppler effect detector which produces a detection signal com¬ carrying a frequency component proportional to the speed of a surface or an obstacle having a relative movement with respect to the leaf.

4. System according to claim 1, characterized in that each detector (20) produces a detection signal proportional to the distance between an obstacle and the leaf.

5. System according to any one of the preceding claims, characterized in that it comprises comparison means (15) arranged to receive and compare each detection signal with a reference signal and to produce a signal proportional to the difference between the two input signals.

6. System according to claim 5, characterized in that the comparison means (15) are arranged to compare each detection signal with several reference signals, and to produce several signals, each of them being proportional to the difference between a detection signal and each of the reference signals.

7. System according to claim 5 or 6, characterized in that the means of. aforementioned comparison (15) are carried out in the detection circuit of each, detector (20).

8. System according to claim 5 or 6, characterized in that the aforementioned comparison means are realized within the controller (30).

9. System according to any one of claims 5 to 8, characterized in that the reference signals are adjusted on the basis of instructions sent by the controller (30).

10. System according to any one of the preceding claims, characterized in that the controller (30) is organized to compare the detection signals produced by the different detectors (20) of the door and emit an alert signal when the detection signals in the absence of an intruding obstacle (no-load operation) are not all identical or when a predetermined number of them are different from the others.

11. Method for adjusting the detectors controlling a revolving door, characterized in that a predetermined speed of rotation is communicated to the door, successively applied to each, means of comparison, a predetermined initial reference signal, then doing gradually and successively decrease each of said reference signals until a measurement signal is detected by the controller, and then the reference signal of each comparison means which controls controls is increased by a first identical increment the relative movement of a reference surface, and finally the reference signal of each comparison means which controls the relative movement of an incoming obstacle is increased by a second identical increment, greater than the first increment in the detection field.