Electrical transmission or interconnection systems – Switching systems – Condition responsive
Patent
1980-01-30
1983-07-19
Pellinen, A. D.
Electrical transmission or interconnection systems
Switching systems
Condition responsive
200 6162, 200 617, 340549, G08B 1308, H01H 316, H03K 1700, E05G 110
Patent
active
043945848
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a switching device for checking the closed position of a folding door in which a signal is released due to the closing movement of the door by means of a switch fitted to the door or its frame.
According to the invention this device can be used with equal advantage on all folding doors in which importance is attached to the reliable checking of their closed state, e.g. prison cell doors, strong room doors, doors of strongboxes and safes.
In a known mechanical switching device of the type defined hereinbefore which is used for monitoring the closing of prison cell doors an electrical signal circuit is closed by the closing movement of the cell door and as a result an acoustic and/or optical alarm signal is given for the guard. In the case of this known device a signal switch with a spring-mounted tripping pin and constructed as a mechanical pushbutton switch is arranged inside the cell door and on closing the cell door mounted so as to swing by means of hinges on the door frame is automatically forced inwards by a stationary switch actuating member provided on the frame and as a result closes the signal circuit.
However, this known switching device is not sabotage-proof because it is possible for an unauthorised person such as a prisoner to operate the switch with the cell door open, i.e. without closing the latter, by pressing the tripping pin inwards by hand or by locking the same, e.g. by means of a match, thereby releasing the door closing signal in order to mislead the guard responsible for the particular prison wing in order to prepare e.g. for a prison riot.
Live magnetic switch devices are also known for checking the closing of a prison cell door in which a magnetic field is closed by the closing movement of the cell door and consequently an alarm signal is released. However, such devices are not deception-proof against stray fields, i.e. they are also not sabotage-proof, because the magnetic field can also be closed when the door is opened by an unauthorised person holding out a piece of iron, e.g. an iron plate which serves as a stray field and as a result a misleading alarm signal can be given.
The object of the invention is to eliminate this disadvantage and its problem is therefore to provide a switching device of the type indicated hereinbefore which is protected in an optimum manner against any manipulations by unauthorised persons, i.e. it is sabotage-proof.
According to the invention this problem is solved by a switching device of the type defined hereinbefore wherein the switching device is made inaccessible to unauthorised persons by covering members connected in undetachable, non-destructive manner to the door and frame.
A preferred embodiment of the invention can be constituted by a mechanical switching device wherein the signal switch arranged on the door and the switching member for the actuation thereof arranged on the frame are located in a common casing comprising a casing base undetachably and non-destructively connected to the door and a casing cap placed thereon and which is locked to the casing base by a safety lock arranged within the casing and detachably and non-destructively joined to the casing cap from the inside and is therefore secured against raising by an unauthorised person, and wherein the casing base has a locking stop covered by the casing cap for the lock bolt which it also covers, whilst the switch and its actuator only become accessible after raising the unlocked casing cap from the casing base.
According to a preferred embodiment of the switching device the switching member comprises an eccentric disc provided on a pin connected in undetachable and non-destructive manner with the frame, whilst a movable switch part of the switch is provided with a roller which runs on the eccentric disc circumference on swinging the door.
According to another embodiment of the mechanical switching device the pin forming a pivot bearing for the casing base passes through a portion of said base which projects over the hinge side of the door and the eccen
REFERENCES:
patent: 3157756 (1964-11-01), Close et al.
patent: 3840715 (1974-10-01), Gwozdz
patent: 3973357 (1976-08-01), Kluempers
patent: 4074246 (1978-02-01), Conklin et al.
Bucher Walter
Spahni Kurt
Bauer Kassenfabrik AG.
Dwyer James L.
Pellinen A. D.
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