Communications: electrical – Condition responsive indicating system – With particular system function
Patent
1980-10-01
1983-01-25
Caldwell, Sr., John W.
Communications: electrical
Condition responsive indicating system
With particular system function
340542, 340545, 200 6162, 200 6164, 200 6167, 116 86, G08B 1308, G08B 2300
Patent
active
043706444
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an alarm device for a door, automatically switched off during a licit access, either that use of a key is made, either that the lock is already unlocked.
This type of alarm device avoids the inconvenience of certain prior devices which had to be switched on only after the authorized persons had left the premises, for example every evening after the closing of a working place or a shop, or when leaving a house, for example, for a trip. One is exposed to an inadvertent alarm if one forgets to set the device out of operation before entering again in the protected premises and, conversely, one is exposed to a break-in if one forgets to switch on the device before leaving the premises.
Alarm devices with automatic switch-off avoiding this inconvenience are already known, for example that disclosed in the Swiss Pat. No. 569.334, in reference to FIG. 5 of this patent, reproduced in FIG. 1 of the drawing annexed herewith. The switch SW1 is arranged in the staple on the jamb-lining, so as to open when the lock bolt is manipulated, cutting off the power supply line from the current source S. The switch SW2 is mounted for example on the top of the jamb-lining and opens if the door is opened or forced. If the door is normally opened, with the use of a key, the opening of SW2 has no effect since SW1, open, cuts off the supply. If, on the other hand, the door is forced without handling the lock, the opening of SW2 starts off the alarm since the relay Ry has contacts C1, C2 which close the alarm circuit passing through the buzzer Bz as soon as the coil Co ceases from being energized. In other words, the relay Ry is closed when it is at rest.
However, this solution presents some disadvantages. As a fact, since the relay is closed at rest, the coil Co which maintains the contacts C1 and C2 spaced apart as long as it is energized, consumes electrical current, and it does so during the whole time when the premises are locked. There results a waste of electric energy. This disadvantage eliminates practically the possibility of building the device with a compact shape comprising its own supply, for example a cell, which would be quickly down particularly at the moment when it would be most needed to generate the alarm signal.
Further, the contacts are arranged on the jamb-lining, which makes the mounting less practical.
The present invention aims at solving problems of this kind by proposing a device where the relay does not take current when at rest and where the contacts are provided on the leaf of the door which makes possible a compact embodiment and makes easier the mounting of the device.
The alarm device according to the invention is characterized in that it comprises a control circuit comprising, in series, an electric energy source, three switches, the first and the second being respectively closed and open when the door is closed and, conversely, open and closed when the door is wide open, but simultaneously closed for the handling phase of the door when, the door being just ajar, the bolt is necessarily retracted, the third switch being controlled by the bolt and closed except when the bolt is retracted, and a relay being interlocked in a working position during the simultaneous closing of the three switches, and an alarm circuit actuated by the relay when said relay is in a working position. Thus, the device starts off the alarm if the door is forced without the pin being retracted.
It is to be noted that the control by switches set in series and a working contact relay, to save electric energy, raises a particular problem that the present invention has solved, the problem is the following: if one takes one's inspiration from a conventional solution, then a switch will close when the door is open (either licitly, either by breakingin) and, to differentiate these two cases, a second switch will be arranged in series with the first one, open if the bolt is retracted, if not, closed. Now, doors exist having a single bolt, controlled both by the lock and by the door handle. Then, in this case,
REFERENCES:
patent: 3653022 (1972-03-01), Tall
patent: 3696374 (1972-10-01), Vosbikian et al.
patent: 3848242 (1974-11-01), Campagna
patent: 4170005 (1979-10-01), Duke
Caldwell Sr. John W.
Crosland Donnie Lee
Geoffrey, Jr. Eugene E.
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