ITMI20111953A1 - SAFETY BARRIER OF THE IMMATERIAL TYPE WITH CROSSED FANS. - Google Patents

Description

"INTANGIBLE SAFETY BARRIER WITH CROSSED VEN-CUTS"

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DESCRIPTION

The present invention relates to a safety barrier of the immaterial type, particularly but not exclusively for accident prevention, comprising at least one infrared ray emitter provided in a TX transmitting unit, and at least one sensor for capturing such rays in an RX receiving unit.

Safety (intangible) barriers of this type are also referred to as "Active Optoelectronic Protection Devices", and with this name they have been taken into consideration to compile European international "standards".

Barriers are known consisting of two columns of active elements, opposed and parallel, containing the same number of radiating and sensor elements: the flat surface between the two columns is crossed by as many beams of rays, mostly parallel to each other, as many pairs of active elements, and such as to create a grid of equidistant beams.

Interrupting even one of the beams produces a change in the logic state of one or more switches present at the output, and this represents the "command signal" for any event, mostly the stopping of the motion of a dangerous machinery.

It is common to use radiation in the infrared frequency range corresponding to wavelengths around 820-950 nanometers.

It is also known the technique of turning on in sequence only one emitter at a time, by means of periodic current pulses lasting a few microseconds, while all the others remain off.

The diodes present in the receivers are activated for the same brief instants and consequently synchronized with the switching on of the corresponding emitters using a special connection between the two TX and RX sections.

The drawbacks of this known system are numerous: the difficulty of precision optical alignment of each pair, which requires complex optical groups which can be oriented in all directions; the impossibility of reversing the direction of assembly of one section with respect to the other; the risk of influencing other receiving sections mounted nearby on other machines with a transmitting section; the need to limit the opening angles of the radiated beam to very narrow values (from 2 ° to 4 °) to avoid dangerous reflections, which cause frequent "machine stops" due to random misalignments caused by very strong vibrations (for example of a press).

The aim of the present invention is to overcome the limitations and drawbacks illustrated above of the prior art.

Within this aim, an object of the invention is to make the installation operation of the barriers on the machines to be protected, their calibration, and their optical orientation simpler, easier and faster.

Another purpose is to realize optical systems of original conception containing both the radiator elements and the sensors, which are such as to increase the range or optical range, without an increase in energy consumed, indeed obtaining a considerable saving both of it and of the number of active and passive electronic components.

This barrier, due to its peculiar construction characteristics, is able to ensure the widest guarantees of reliability and safety in use.

This and other purposes, which will appear more clearly later on, are achieved by an immaterial safety barrier comprising at least a first column containing a plurality of emitters or radiators, each of which is capable of emitting infrared radiation rays with a predetermined opening. through a slot in said first column.

The barrier also comprises at least a second column containing a plurality of receiving elements, including optical-electrical sensors, capable of receiving the rays emitted by the aforementioned emitting elements through a slot in said second column, so as to create a curtain of fan-shaped rays. crossed to detect the crossing by a solid body.

The barrier is characterized by the fact that each of the aforesaid emitters comprises a lens which concentrates, transversely to the slot, the beam emitted by each radiator, and that each of the receivers receives the rays emitted by two or more emitting elements.

Further characteristics and advantages of the object of the present invention will become more evident through an examination of the description of a preferred but not exclusive embodiment of the invention, illustrated by way of non-limiting example in the attached drawings, in which:

Figure 1 shows a perspective, schematic and partially sectional view of the transmitting part of the barrier which will be defined hereinafter with TX, ie the column containing especially the infrared radiation emitters;

Figure 2 is a view similar to Figure 1 and illustrates the column containing the receiver elements together with the connected circuits;

Figure 3 shows, by means of dashed lines, the paths of some rays which make up the curtain of active crossed beams; figure 4 represents an orientable support shelf;

Figures 5 and 6 show a preferred solution of optical system for radiators;

Figures 7 and 7A indicate a preferred solution of the optical groups contained in the RX receiving section;

Figures 8, 9 and 10 show the comparison between the paths of the beams of rays of a known barrier and those of the system object of the present invention;

figure 11 represents the illustrative block diagram of the circuit of the transmitting column TX;

figure 12 represents the block diagram of the circuit contained in the RX receiving section;

Figure 13 illustrates the creation of the halos of a "spot" caused by a non-point source;

Figure 14 demonstrates the presence of the "black hole" in an infrared ray generating diode;

figure 15 explains the reception of the reflected rays;

Figures 16 and 17 show examples of asymmetrical barriers.

With particular reference to the numerical symbols of the aforementioned figures, the barrier, according to the invention, comprises a container 1 for the transmitting section (TX) of the barrier, and a container 2 for the receiving section (RX), represented respectively in Figures 1 and 2 .

For the sake of brevity, the two sections, being two well separated entities, will be indicated in the course of the description with TX and RX.

The containers 1 and 2 have similar construction and are preferably made with a rigid extruded wire of infrared opaque material.

They preferably have a U-shaped section with two flaps on the shorter side which is open, so as to form a narrow slot 3, which allows the ray beams of the container 1 to exit and enter the container 2.

These slits are closed by a removable strip of filter material 4, which prevents the passage of visible light which would constitute a disturbance, and allows only the passage of infrared radiations emitted by the emitters (radiators) 8 arranged in the container 1 and received by integrated groups of receivers 9 arranged in the container 2.

All the electronic components are mounted on printed circuit boards or boards 5 and 12 which are easily removable from the container thanks to internal guides with which they are suitably provided.

In cards 5 and 12 the metal tracks that constitute the ground conductors, on both sides, are suitably connected to the ground of the containers 1 and 2 if they are metal, by means of decoupling capacitors to avoid electrical disturbances.

Each of the radiators 8 of the TX section is mounted on a support 10, preferably orientable in the direction parallel to the slot 3.

This support is opaque to infrared and closed, on the part facing this slot, by a 7 - 11 lens.

Figures 5 and 6 show two types of lenses, one preferably of semitoroidal shape, 7, and one with a slice section of a plane-convex cylinder 11, according to whether the distance to be overcome between TX and RX is small or large.

Figure 6 shows the most convenient lens shape for the first solution.

The function of the lens 7 or 11 is to narrow the emission cone laterally so that the beam does not unnecessarily affect the internal side walls of the container 1, so that almost all the radiated energy is conveyed only towards the narrow slot of output 3, and vertically distributed in a fan shape with intensity distribution as uniform as possible towards the RX unit.

The supports or projectors 10 are conveniently orientable, for example around a pin 13, in the vertical direction of the container 1, that is, in the longitudinal direction of the slot 3, so as to make possible a uniform "illumination" of the entire opposite RX section, from each of them, oriented for the best according to the position that comes to assume in the row.

On the opposite side, ie inside the container 2, each receiver 9 comprises a sensor element 14 arranged in a monolithic integrated block 17 together with other components, as will be illustrated hereinafter.

Block 9 is equipped with a first hemispherical lens, surmounted by a second wide-angle lens 16 (cylindrical-convex with an almost spherical section in the vertical direction of the cylinder) suitable for receiving the radiations coming from all the radiators of the opposite TX section of the barrier, and focusing on the sensitive element 14, embedded under the first lens 15 formed in thermosetting resin and filtering the infrared.

Figure 7 is a longitudinal section of the device and Figure 7A is a cross section.

Figure 3 schematically represents a part of the active paths of the beams of rays contained in the entire fan radiated by the first two emitters 8 of the upper end of the TX section and received by the sensors 9 of the opposite RX section.

The active elements 8 of the TX are preferably orientable, while the sensors of the RX section are equipped with the wide-angle lens 16 and have a viewing angle sufficiently wide to convey the rays coming from any direction, in the vertical direction, onto the sensitive element 14.

According to an important characteristic of the present invention, the integrated circuit contained in 17, together with the internal lens 15, are molded in one piece, preferably in black methacrylate, transparent to infrared and opaque to visible light.

The box containing the receiver 9 together with the lens 16 is made of the same material.

In this way the two lenses 15 and 16, together with the filter 4 for closing the slot 3 on the container 2, constitute three filters in succession, so as to shield as much as possible the disturbing lights coming from the outside, making them inactive up to a luminous intensity. of about 40,000 lux.

For technical convenience of molding, the elements 9 and 16 can be separated.

On the contrary, the lenses 7 - 11 of the emitters do not need to be opaque to visible light, but only transparent to infrared.

Figure 4 represents a fixing means for the containers 1 and 2, in particular a shelf, preferably molded in thermoplastic and usable with two different mounting directions, which can be inserted into a pin which provides the possibility of locking and rotating.

Countersunk screws are inserted into a dovetail slot 6, with which the drawn sections of the rigid containers 1 and 2 are fitted at the rear.

They can be in any number, according to the need for fixing by means of anti-vibration supports, according to the height of the bars themselves.

The supports in figure 4, reversible as well as rotating, are applied only to the two ends of each TX and RX section of the barrier.

To better understand the purpose of Figures 8, 9 and 10, we report here the definition of the term "resolution" of the beam curtain formed by an immaterial barrier.

"The resolution corresponds to the minimum diameter, expressed in millimeters, in that cylinder which, when introduced into the curtain, is intercepted by its rays in all points of its surface".

In figures 8, 9 and 10 the two systems are compared, the standard one with parallel rays of figure 8 with that of figure 9 and figure 10 representing the path of the fan-shaped ray beams adopted in the present invention.

It is graphically evident in figure 9 that, by adopting the cross-ray fan system, the resolution becomes the same as that of figure 8 (with parallel rays of the standard type) even with a spacing of the active elements even doubled.

Figure 10 shows how, with the same number of active pairs, the maximum resolution acquired by the fan system is double that of the standard system of figure 8 (diameter of the intercepted cylinder measuring half).

It is also clearly demonstrated geometrically by figure 10 that, with the fan system, the nominal value of the resolution is obtained only in some unfavorable points of the beam network, while in all the others its value is much higher than the nominal one.

The disadvantages have been considerably improved by approaching the extreme optical pairs, both of the transmitting TX and receiving RX unit (optics 0 and optics 6 in figure 10).

Figure 1 1 illustrates in a simplified way and only for demonstration but not limitative purposes, the theoretical operation of the TX (transmitting) section of the barrier object of the present invention.

It provides two rectangular pulse generators 18 and 19.

The oscillator 18 generates pulses at an ultrasonic frequency (preferably from 38 to 56 KHz), while the oscillator 19 generates almost rectangular pulses at a much lower frequency (preferably between 400 and 800 Hz).

The frequencies chosen as an example are those suitable for the realization of a barrier referred to the current state of the art of the available electronic components, however they are not binding.

The rectangular pulses of the oscillator 18 have therefore, in the example cited with the frequency of 38 KHz, a cycle of duration (period) of 1 / 38,000 equal to about 26 microseconds, and their duration is adjustable (in the present case à A duty cycle of 50% has been chosen) depending on the ability of the radiator element to follow the variations from zero to the maximum of radiation and go back down from maximum to zero in times of less than 26 yt / s.

The pulses generated by the oscillator 19 have a much longer period (1 / f), that is 1/400 = 2500 microseconds and their duration (25 in the figure) is for example fixed at 300 microseconds interspersed with an inactive time ( 26) equal to 2500-300 = 2200 Hs.

The pulses of both generators are mixed in a suitable logic circuit (not shown) and then injected through the driving units or "drives" 22 into the emitters or radiators 23 of infrared radiation invisible to the human eye.

A distributor 20 sequentially enables the emitters, one only at a time for the duration 25 of 300 / vs so as to obtain a number of 300/26 = approximately 11 short pulses (those with a duration of 26 Î1⁄4ε).

The number of 1 1 corresponds to a code necessary so that the calibrated PLLs of each individual receiver (which will be described below) can be activated, while the inactive time 26 is necessary to allow the radiating elements 23 to cool in the interval between one ignition and the next.

Schottky diodes 21 are arranged on each output of the cyclic distributor or counter 20.

A constant current regulator is a further monolithic integrated group 24 which allows to regulate, by means of a potentiometer incorporated in it and with only the pin accessible and graduated, the intensity of the impulses that are sent to the emitters 23.

Referring to figure 12, it represents in a simplified way and for illustrative but not limiting purposes, the block diagram of the main electronic components, active and passive, of the X-ray receiving section of the immaterial barrier object of the present invention.

Through the use of integrated components and other miniaturized components, and thanks to a surface mounting in each of the monolithics 9, all the functions performed by the following elements have been grouped:

- the photodiode 14 which constitutes the infrared sensor, equipped with a lens 15, opaque to visible lights and transparent to infrared;

- the lens 16, cylindrical plano-convex or cylindrical plano-convex-semitoroidal, composed of the same black material, conveniently obtained by molding in a single body with the container 9, or superimposed on it by welding; it converges the received rays and concentrates them in the "chip" which houses the receiving photodiode 14;

- the operational amplifier (OPAMP) 27 conveniently mounted also as a band filter so as to amplify only the useful frequencies;

- the Phase Locked Loop PLL, 28 equipped with its own oscillator and Open Collector output, which constitutes the key for opening reception exclusively on the frequency radiated by the transmitters of the TX transmitting section;

- the trigger trigger (Schmidt trigger) 29 provided with a certain hysteresis, which intervenes when the signal received by the diode 14 corresponds to the code of the PLL, 28;

- the group of diodes 30 (double series in double parallel) which guarantees the safety of operation in case of failure of one of them, which would not happen if the output were performed through a single diode.

The output is split on two different leads, spaced apart, with a ground lead interposed, again to obtain enabling when the integrated assembly 9 is subjected to the test of the faults caused.

On the roof of the integrated there is a fifth contact T (TEST), useful for instrumental control during the testing phase.

The monolithic IC is repeated as many times as there are sensitive points needed inside the RX section, and the ICs are arranged equidistant or not, according to need, on a printed circuit board 12 (figure 2) inserted inside the container 2 of the RX so that the lenses are at the maximum distance from the entrance slot of the ray beams.

A few other components are mounted on this board which, due to their irreducible dimensions, do not fit conveniently inside the integrated monoblocks, such as the electrolytic capacitors, the light emitting diodes (LED), the voltage regulator, the variators (Voltage Dependent Resistors VDR), the power supply conductors and the two output switches 33, the two protection fuses, etc.

Two other monolithic integrated groups 31 - 32 are mounted on the board 12, in the interspaces between the blocks 9 which, for a resolution of for example 40 mm, are spaced by 80 mm.

They contain, in more convenient integrated groupings, a comparator calibrated in such a way that the lack of a single pulse of the sequence sent by all the receivers prevents the maintenance of the subsistence level for which it does not cause the going into alarm, i.e. the final switch opening command click.

Also in the monolithic 31 - 32 switches are integrated consisting of open collector transistors (Open Collector) or Open Drain (Open Drain) which control the LEDs contained in the two final control solid state switches 33.

It is not necessary to illustrate in detail the circuits of the single groups 31 - 32 - 33 as their particularity does not lie in the type of component contained or in the scheme of their connections, but in the fact that they have been carried out in the form of monolithic integrated their respective components are divided in such a way as to have the minimum number of inputs and outputs; the latter are arranged in such a way as to fully satisfy the safety test of the faults caused.

This requirement is in fact essential for an electrosensitive safety protection which is obtained, according to the invention, by means of the particular block division of the necessary components and their integration in monolithic assemblies.

Figure 13 illustrates the reason why an emitter element of general use, such as a gallium arsenide crystal diode, cannot provide a clearly defined beam of rays on the edges of the cone section generated by it, due to the source which is not point-like, but has a certain surface.

The transparent mass 34 ends with a lenticular surface 35 and contains, at the calculated distance f, the crystal 36, of normally square area.

It is geometrically demonstrable that the cone of rays exiting the exact center has an angular aperture, aA, in section, corresponding to that due to its distance from the focal point of the lens 35.

All the other points of the radiating surface will have, such as those located on the edges of the square, a cone no longer in axis with the lens 35, thus forming many halos from aB to aC, more and less convergent than the central one aA.

The presence of a second lens 7 - 1 1 only worsens the spreading of these scattered rays.

In figure 14, keeping the numbering equivalent to that of figure 13, the examination of the radial element is resumed.

tor 8, and more precisely the presence on the crystal 36 of a metallic deposit 37 which is non-radiating (inert) of infrared and usually star-shaped.

This metallization is necessary in order to be able to convey the "ignition" current to the upper surface of the crystal by means of a thin "whisker" 38 welded on the rheophore 39 coming out of the crystal; the insulating mass.

A lead 40 acts as a second conductor and the lower surface of the crystal is welded to it, of opposite polarity to that of the lead 39.

The presence of this "spot" on the crystal produces the defect of the "black hole" exactly in the center of the "spot" or radiated beam, that is, when you try to obtain the "spot" of minimum size with a converging lens, it is form when the focal point of the lens matches the plane of the crystal. The radiated ray beam will have the minimum diameter, but with zero irradiation at its exact center.

To eliminate the defect it is necessary to "blur" the lens causing on the other hand a cone of greater diameter and surrounded by halos.

The drawbacks illustrated in figures 13 and 14, while they create great difficulties in standard type barriers, to obtain very narrow beams, are irrelevant in the barrier object of the present invention due to the fact that it is calibrated with the system of the minimum irradiation level.

Figure 15 illustrates the reason why by using the minimum radiated power system adopted in the present invention, the requirement of no harmful influence of reflective surfaces near the dangerous zone, ZP, is achieved.

The irradiating element 8 together with its lenses, sends a beam of rays towards the optical apparatus of the sensor 14 opposite and aligned in the best possible way.

The main beam of rays 101 starts with a diameter corresponding to the maximum aperture of the last lens and is surrounded by a myriad of scattered rays, as explained in figure 13, with mostly diverging trajectories.

The main beam 101 by means of the regulator 24 of figure 1 1 is adjusted according to the distance between the emitter 8 and the receiver 14 to the minimum intensity value necessary to keep the sensor 14 hooked, for example 100 lux, measured at the center of 14 The adjustment is carried out so precisely that a 5% drop in illumination, or 95 lux, is enough to lose the catch of the RX receiver and trigger the machine to stop.

By examining the ray 102 which is part of the scattered beams and therefore already rising with an attenuation of 10% due to its divergence β (deducible from the radiation diagram) it can affect a possible reflective surface 103 with an angle a and be reflected at the same angle a in the direction of the receiver 14 with trajectory 104.

This ray, which is the reflected continuation of ray 102, already attenuated to about 90 lux due to its already examined divergence β, undergoes a further reduction due to the losses by reflection which, according to the various glossy surfaces, can vary from 50 % to 15% (silvered glass mirror).

The intensity of 90 lux of 102, when it becomes 104 drops to 90 x 0.85 = 76.5 lux (if we consider the 15% loss).

It remains to be taken into account the further loss due to the misalignment at the entrance of the optics of the receiver 14, which, in the horizontal sense, has a very small field opening.

From measurements made, this loss is at a minimum of 20%, so that the reflected ray 104 enters 14 with intensity 76.5x0.8 = 61.2 lux.

The electronic circuit controlled by the receiver 14 has been calibrated thanks to the regulator 24 to lose the connection with the radiator at the reduced intensity below 95 lux.

Therefore it will not be able to engage with a beam of intensity 61.2 lux received by reflection, when the direct beam 105 is missing due to the presence of a person or an object.

This safeguard would not be possible if the intensity of the radiator had been fixed during the construction phase at an immutable fixed maximum value, ie at that value necessary to obtain the maximum range, as commonly occurs in all known barriers.

In practice it has been found that the invention achieves the intended aim and objects.

In fact, a barrier has been created which ensures a much higher efficacy with considerable savings in components.

It also uses numerous beams of beams arranged in a fan shape, one for each emitter, and the reception in wide angle mode of all the beam fans emitted by each receiver.

This barrier offers many particular advantages, in addition to the main one of the formation of a grid of crossed beams, rather than parallel ones, the number of which is no longer equivalent to the number n of the pairs of active elements, as in standard barriers, but becomes equal to the number nTX of radiators multiplied by the nRX number of receivers.

For example, if with a parallel ray system having seven pairs of elements we obtain seven parallel ray beams (figure 8), with the fan system (figure 10) we obtain forty-nine beams, it is moreover with doubled resolution , that is, for the same value of the resolution, a halved quantity of active elements is required (figure 9).

According to the invention, the electronic circuit of the present barrier has been divided into many monolithic integrated "assemblies", each containing a board or plate on which the discrete components are mounted, made inaccessible to external agents.

These boards, preferably mounted with the S.M.D. The (Surface Mounting Devices) are considered as monolithic integrated, from which only the rheophores or input and output terminals (INOUT), power supply and ground come out.

The boards are designed by arranging, if necessary, the leads interleaved and repeated, in order to make the assembly pass the test of the provoked failures.

In this way, one of the circuits that characterize the present invention was also created, that is the one responsible for linear regulation (from zero to maximum) of the power radiated by the emitters, so as to be able to calibrate them to the minimum level necessary according to the sensitivity and of the distance of the opposite sensors.

This is an innovative feature compared to standard barriers so far on the market, and which allows you to easily avoid, through a simple adjustment, the possibility of errors due to a beam reflected from surrounding glossy surfaces.

In this regard, Figure 15 illustrates the result of tests carried out.

A dispersed ray 102, emitted by one of the emitters 8 and forming part of the inevitable peripheral halo of the radiation cone 101, has, with respect to the direct central beam 105, an intensity already reduced by at least 5%, due to its ec centricity.

It is assumed that this secondary ray 102 may encounter a shiny surface 103 within the dangerous area, cutting it at an angle, being reflected therefrom, as a ray 104, at an equal angle a towards the sensor 14 of the RX section.

This reflected beam 104 will enter the optics of the sensor 14 with an even more eccentric direction angled by an angle a for which it will undergo, for optical reasons, a further attenuation of 10%.

These losses in intensity are also added to the loss due to reflection, which in the best case (silver glass mirror) will not be less than 15%.

The result will be that the reflected beam 104 will be so weak that it can never be confused with the direct one 105 because the intensity of the latter has already been reduced to the operating limit of the barrier thanks to the regulator 24 of figure 11, and one part cannot replace the entire beam 105 should it fail due to the intrusion of an opaque body.

The introduction of a regulator of the power radiated by the TX transmitting section of the infrared barrier is also an innovation. In fact, in the barriers built to date, the achievement of this requirement has been sought by other means, for example by restricting the angles of emission and reception, which were less effective and spoiled by further drawbacks.

Naturally, the materials used, as well as the dimensions, may be any according to requirements.

Claims (15)

R I V E N D I C A Z I O N I 1. Immaterial safety barrier comprising: at least a first column (1) containing a plurality of emitters or radiators (8), each capable of emitting infrared radiation rays with a predetermined opening through a slot (4) in said first column ( 1), and at least a second column (2) containing a plurality of receiving elements (9), comprising optical-electrical sensors (14), capable of receiving the rays emitted by said emitting elements (8) through a slot (4) in said second column (2), so as to create a curtain of crossed fan-shaped rays capable of detecting the crossing by a solid body; characterized in that each of said emitters (8) comprises a lens (7, 11) which concentrates, transversely to the slot (4) the beam emitted by each radiator (8), and which each of the receivers (9) receives the rays emitted by two or more of said emitting elements (8). 2. Barrier according to claim 1, characterized in that said lens is a plano-convex lens (11) shaped like a longitudinal slice of a cylinder cut axially. 3. Barrier according to claim 2, characterized in that said lens is a plano-convex lens, which is further longitudinally shaped according to an arc of a circle or ellipse. 4. Barrier according to claims 1 to 3, characterized in that each of said radiators (8) with lens (7, 11) is mounted on a pin (13) to allow the orientation of the emitted beam to be adjusted. 5. Barrier according to the preceding claims, characterized in that each of said receiving elements (9) is made as an integrated monolithic component (14, 17) equipped with a converging lens system comprising a cylindrical external lens (16) -piano-convex with substantially spherical section in the vertical plane. 6. Barrier according to claim 5, characterized in that said lens system further comprises an internal lens (15) having a substantially hemispherical shape. 7. Barrier according to any one of the preceding claims, characterized in that each of said radiators (8) is fed with substantially rectangular impulsive signals, generated by different oscillators (18, 19), mixed so as to obtain a code sequence that can be decoded by the corresponding sensors (14) for frequency identity as well as for phase locking. 8. Barrier according to claim 1, characterized in that it comprises a circuit for regulating the power radiated by each of said radiators (8), comprising a potentiometer, said circuit and potentiometer being incorporated in a monolithic block of insulating material from which it emerges only the pin of said potentiometer. 9. Barrier according to claim 1, characterized in that each receiver further comprises an operational amplifier, a phase-locked circuit with relative oscillator, a Schmidt trigger and a series of protection diodes, all incorporated in a monolithic block of insulating material. 10. Barrier according to claim 1, characterized by the fact that all the receiving groups converge their outputs on a first monolithic integrated unit used to detect the possible lack or occlusion of one or more beams of rays of the immaterial curtain, followed by a second integrated ; the transistors with open collector (Open Collector) or open drain (Open Drain) outputs are designed to drive the two final switches and the logical status indicator lights of the outputs themselves; both ICs are provided with a few input-output leads arranged so as to satisfy the failure test. 1 1. Barrier according to claim 1, characterized by the fact that the receiving section is constructed with the double channel technique (doublà © channel technique) up to two separate output switches, in the solid state (without moving parts), through which can be driven by two independent loads, in phase, or one load only if connected in series, but with doubled safety, such as to reach a level 2 and level 3 safety degree respectively (if connected in series); this degree can be raised to level 4 (according to the regulations in force) by means of an external continuation control unit, thanks to the fact that it is built using components and circuits that meet the highest level of safety, except for the circuit, which is missing, to control the parity of the state logic of the two outputs. 12. Barrier according to claim 1, characterized by the fact that it can be used in many cases and individually up to danger levels of class 3 and that its receiving section can be continued by a special control unit to be mounted separately but to be considered as an integral part of the whole barrier, as a safety component responsible for controlling the logic state of the two outputs of said section, as well as as a controller of the efficiency of its two final machine control switches; the same control unit signals operations and any malfunctions by means of warning lights, inhibiting consent in the event of any operating anomaly. 13. Barrier according to claim 1, characterized in that the output switches of the receiving section and those of the logic parity controller are of the self-controlled solid type with a redundancy circuit; they can directly drive any programmable controllers (PLC) without the need for anti-bounce adapters, and are equipped with a limiter for the maximum level of current absorbed by the load and therefore excluded from the possibility of their damage due to short circuits or overloads. 14. Barrier according to claim 1, characterized in that the number of active elements of the transmitting unit (TX) may differ numerically from the number of active elements of the RX receiving unit, generating an asymmetrical crossed beam curtain (Fig. 16 - Fig . 17). 15. Barrier according to claim 14, characterized by the possibility of installing the two units upside down, one with respect to the other, without accurate parallelism precision.