Illumination – With static structure – Wall or ceiling
Reexamination Certificate
1999-01-08
2001-02-13
O'Shea, Sandra (Department: 2875)
Illumination
With static structure
Wall or ceiling
C362S270000, C362S371000, C340S541000, C340S556000
Reexamination Certificate
active
06186639
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns an optical safety barrier which is intended in particular for the prevention of access to industrial installations, and consists of:
a unit containing the electronic and optical components, the transmitters and the receivers,
this unit, mounted in a manner which can be adjusted optically by its two ends, about an axis, in two supports connected to a fixed object (wall, structure, framework, etc.),
the two ends of the unit correspond to two supports, each of which is connected by a pivoting link (pivot/bearing) to the supports in order to allow optical adjustment of the barrier, and
the means of locking the pivoting link in position.
2. Description of the Related Art
There are numerous areas in which it is necessary to prevent or forbid access to a zone using a nonmaterial barrier, such as infra-red rays, to forbid access to a dangerous machine. Such barriers can also be used to protect sensitive areas, to prevent access or to detect an intruder.
The nonmaterial safety barriers used to protect people working on dangerous machines are becoming more and more reliable. Nevertheless, if they fail, it is necessary to replace these barriers very quickly so that the machine should not be prevented from operating. This is all the more important since the protected machines frequently form part of a production line, and halting any one machine affects the whole of production.
In addition to the process of disconnecting the electrical supply, the replacement of a faulty barrier involves the mechanical dismantling of the barrier, the installation and electrical connection of the replacement barrier, and the optical adjustment of the newly-installed unit, Now this optical adjustment process is very costly in terms of time, and its also has to be carried out by equipped and specialist staff.
The aim of this invention is to provide a remedy for these disadvantages, providing it with the potential to create a safety barrier for which replacement is a very quick and simple operation which can be performed with no danger to unqualified staff.
SUMMARY OF THE INVENTION
To this end, the invention concerns an optical safety barrier of the type described above, characterised so that:
at least one support includes an adjustable mechanical positioning device which is adjustable in accordance with the optical setting of the unit.
the end of the unit is equipped with a fixed aperture to receive the positioning device borne by the support and locked at the set position.
In the event of total or partial barrier failure, it is necessary only to free the unit in relation to its support components, in general from one upper device and one lower device, to move aside one of these supports if necessary, to extract the defective unit, and to install a new unit. This installation is achieved very simply. It suffices merely to position the two pivot/bearing connections and to pivot the unit in relation to one of these supports so that the positioning device on the support automatically corresponds with the positioning aperture of the unit. On completion of the installation process, the unit is then locked in position by tightening up the locking screws of the support or supports.
The electrical connection can then be restored, and the barrier is ready for use.
According to another very advantageous characteristic, the support or supports of the unit take the form of two brackets.
On the basis of a further advantageous characteristic, the positioning device is an oblong curvilinear aperture, centered on the pivoting axis of the unit in relation to the support, and accommodating a nut and bolt link which is tightened up once optical adjustment has been effected.
The oblong curvilinear aperture for the positioning device and the oblong curvilinear aperture for the locking device constitute a very useful solution owing to its versatility, being suitable for all possible orientations of the unit in relation to the support.
In fact, depending on the machines or the support surfaces concerned, the orientation between the surface and the unit, that is the orientation which the barrier must present, is never fixed in a precise manner prior to initial assembly, nor is it uniform for all installations. Only the surface is fixed—in general the plane, or more usually the transmission-reception surface constituting the nonmaterial barrier. Now this plane can have any orientation in relation to the support, and in general this orientation is not known, and need not be known since the positioning device allows a new unit to be positioned automatically with no need to concern oneself with any optical adjustments.
In a particularly advantageous and simple manner, the locking device is composed of the following:
an oblong curvilinear aperture, created in the support, and centered on the pivoting axis,
threading tapped in the end corresponding to the unit, and a bolt passing through the oblong aperture to connect with the tapped threads.
According to another very advantageous characteristic, the mechanical positioning device and the locking the pivoting link between the unit and its supports are accessible only by means of tools which are different in nature.
It is very important that the person who is replacing the defective unit, and who is necessarily unqualified, should not be able to alter the setting of the positioning device accidentally. To this end, it is particularly useful that the tool used to remove the faulty unit and to install the replacement unit, cannot be used in the mechanical positioning devices.
In order to achieve such a characteristic in practice, it is useful that the positioning device has a slot-head screw and that the locking device has a hexagonally-headed screw. In these conditions, there is never any danger that the slot-head screw will be undone by the hexagonal spanner.
If the positioning device should happen to be loosened accidentally, in the case of two positioning devices, that is two supports fitted with one positioning device each, it will still be possible to re-position the new unit, and to lock the disturbed positioning device after the replacement unit has been installed.
If only a single positioning device is used however, it is essential that any disturbance of the positioning device be avoided.
According to a further beneficial characteristic of the invention, the positioning device has a slot-head screw and the locking device has a hexagonal-head screw.
This solution is particularly useful because the unit is composed in general of an extruded tube, cut along its length, and fitted at both ends with a cover. The cover, which is an injection moulded part, in a polymer material for example, can have a relatively complex shape.
Finally, according to another advantageous characteristic of the invention, the positioning and locking devices at each end of the unit are doubled-up, this constituting an additional safety factor.
REFERENCES:
patent: 4130860 (1978-12-01), Careglio et al.
patent: 4507719 (1985-03-01), Quiogue
patent: 5302942 (1994-04-01), Blau
patent: 5550725 (1996-08-01), Shemitz et al.
patent: 2 022 820 (1979-12-01), None
O'Shea Sandra
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Schneider Electric SA
Ward John Anthony
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