US3740648A - Distress call signalizer of the miniature transmitter type - Google Patents

Abstract

A distress signal transmitter circuit comprising a positionsensitive mercury switch, and a pressure-sensitive mechanical switch, coupled in parallel to a transmitter and a power supply. A continuously charging-discharging capacitor, coupled to the power supply and the transmitter, causes the generation and transmission of signals at predetermined intervals. Displacement of the mercury switch or pressure on the mechanical switch, interrupts the transmission of the signals at the predetermined intervals and causes a continuous signal to be transmitted by the circuit, thus indicating a distress condition.

Description

United States Patent 1 Grotjahn [4 1 June 19, 1973 DISTRESS CALL SIGNALIZER OF THE MINIATURE TRANSMITTER TYPE [76] Inventor: Alfred Grotjahn, Schmiedestrasse 35, Burgdorf, Germany [22] Filed: Oct. 27, 1971 [2]] App]. No.: 192,835

[30] Foreign Application Priority Data Oct. 23, I970 Germany P 20 52 939.9

[52] U.S. Cl 325/113, 340/200, 340/224 [5l] Int. Cl. "04b 1/04 [58] Field of Search 325/11], 113, ll4-ll9;

[56] References Cited UNITED STATES PATENTS 3,336,530 8/[967 Sloan et al. 325/113 2/1970 Goodman et al. 325/1 [3 13/1965 Pierce 325/1 15 Primary Examiner-Albert J. Mayer Attorney-Allison C. Collard [57] ABSTRACT A distress signal transmitter circuit comprising a position-sensitive mercury switch, and a pressure-sensitive mechanical switch, coupled in parallel to a transmitter and a power supply. A continuously chargingdischarging capacitor, coupled to the power supply and the transmitter, causes the generation and transmission of signals at predetermined intervals. Displacement of the mercury switch or pressure on the mechanical switch, interrupts the transmission of the signals at the predetermined intervals and causes a continuous signal to be transmitted by the circuit, thus indicating a distress condition.

4 Claims, 1 Drawing Figure TRANS- w5 MIT TL'R PAIENTED JUN1 91975 3 740 648 TRANS- MITTER DISTRESS CALL SIGNALIZER OF THE MINIATURE TRANSMITTER TYPE DESCRIPTION The present invention relates to a distress signal transmitter circuit for attachment to a person or object for signalling a distress situation to a remote receiver.

An object of the invention is to provide an improved distress or emergency call signal transmitter which transmits a distress signal to a remote receiver tuned to the transmitter, producing in this way a distress signalling system always ready for use. This object is achieved according to the invention by connecting a rhythmical pulse generator in parallel to a gravity responsive switch, and a pressure-sensitive mechanical switch. Displacement of the mercury switch, or the application of pressure on the mechanical switch, generates an alarm signal which is transmitted to the remote receiver. As long as the distress call signalling circuit is not interrupted by the mercury or mechanical switches, the transmitter sends out a signal at regular intervals which, likewise, maintains the receiver in a state of readiness for operation. As soon as the rhythm of these pulses is interrupted or interfered with by activation of the mercury or mechanical switches, the change in the,

transmitted signal is detected by the receiver, which then generates a visual or audible alarm signal indicating a distress condition which can be observed on the receiver by the monitoring personnel and can be remedied or repaired at once. The rhythmical pulse generator consists preferably of a capacitor which discharges at predetermined intervals thereby generating the pulse. If the pulsesare not sent out at the predetermined frequency to which e.g. a time-lag relay mounted on a receiver is tuned, then the technical alarm is given in the receiver. This occurs even when, in fact, the distress call signalizer is in order, yet its current sourceconsisting e.g. of button type dry batteries is exhausted or the voltage available is no longer sufficient.

Performance reliability of the distress call according to another object of the invention by connecting in parallel to its current source, a second power source via a second member dependent on said voltage. This second power source is connected to the circuit of the distress call signalizer when the first current source no longer has sufficient voltage. In this way continuous performance reliability of the distress or emergency call signalizer is achieved even when the current source has become exhausted.

These and other objects and advantages will become apparent from the claims and from the following detailed description when read in conjunction with the appended drawing representing schematically an embodiment of the invention.

The emergency call signalling circuit comprises a housing (not shown) having the shape and size e.g. of a cigarette box with a battery 6 constituted, for instance, by button type cells, and a miniature transmitter which sends out a fixed frequency when connected to battery 6. This frequency is selectively received by a receiver (not shown) located in the vicinity and transferred via an integrating circuit to release the alarm. A mercurytoroid tube switch 7 is coupled in parallel to a pressure-sensitivemechanical switch 11 which is responsiveto pulling or pushing forces exerted on a pivotable cover mounted on the housing.Switches 7 and 11 are coupled to battery 6 and totransmitter 5. Switch 11 includes two resilient external contacts 118 and 11C mounted on the outside of the housing which are connected totransmitter 5 by achangeover switch 10.Switch 11 also includes a resilient center contact 1 1A which is connected to one of the terminals of battery 6 andminiature transmitter 5 there are, in addition to the mercurytoroid tube switch 7, a change-overswitch 11 parallel thereto which is responsive to pull or pressure exerted on a swivel hinged housing cover and comprises two resilientexternal contacts 11b and 11c alternatingly connectable via change-overswitch 10 to theminature transmitter 5, as well as aresilient center contact 11a permanently connected to one pole of battery 6. In the upper half of the mercurytoroid tube switch 7 there is provided acentral contact 7a, directly connected to battery 6, as well as the contacts 7b and on the left and the right side and connected inparallel with each other. These later contacts are connected to the transmitter via cut-out or disconnector 2. The filling of mercury 9 is, when the device is in the position of service, in the lower circumferential half portion of the toroid tube being of circular cross section. It closes its respective pairs ofcontacts 7a, 7b and and 7a, 70 of the mercurytoroid tube swith 7 when swivelled to the left or the right. I

According to the invention acapacitor 14 is connected in parallel with thetoriod tube switch 7 to in-' sure continuous operational readiness of the emergency call signalling circuit. Thecapacitor 14 is proportioned so as to discharge at specified intervals, having thetransmitter 5 transmit a signal which does not produce an alarm signal in the receiver. It is only when the pulse rhythm transmitted by thetransmitter 5 is interrupted or disturbed that the receiver generates an alarm signal which notifies monitoring personnel that a distress situation exists. In order to assure that the emergency call signalling circuit is maintained in operational readiness even when the battery 6 has become exhausted there is connected asecond battery 16 parallel to battery 6 via a voltage-dependent switching member 15 constituted e.g. by a corresponding relay. Thebattery 16 become active when the voltage of battery 6 sinks below a predetermined limit value, thus making switchingmember 15 responsive.

The operation of the signalling circuit is as follows:

Transmitter 5 is coupled to battery 6 bycapacitor 14, whose capacitance is chosen so that its breakdown voltage is lower than the voltage of battery 6. Switch 2 is closed in order to render the circuit responsive to switch 7.Transmitter 5 generates a signal at a predetermined frequency which is interrupted intermittently at a specified rate by the discharging and charging ofcapacitor 14, thus resulting in the generation of a series of pulses, spaced apart at predetermined time intervals, which are transmitted to the remote receiver of the system. When the housing in which the circuit is disposed is displaced horizontally, or upside down, mercury 9 inswitch 7 bridges the gaps between contact members 7A and 7B or7C, thus or 7C,transmitter 5 directly to battery 6, bypassingcapacitor 14, so that the transmitter emits a continuous signal at the specified frequency. This change in the signal transmitted is detected by the receiver, which sets off an audible or visual alarm to attract the attention of monitoring personnel. The receiver utilizes a conventional detector to detect the signals transmitted by the signalling circuit. When pressure is exerted on the housingadjacent switch 11, or the cover thereof is attempted to be opened, one of contacts 118 or 11C engages contact 11A andcouples transmitter 5 directly to battery 6. The transmitter then generates a continuous single frequency signal as described previously. Switch enables the circuit to be set to respond to either pressure or pulling forces exerted on the cover of the housing.

The housing in which the signalling circuit is disposed is attached to an object or carried by a person. The mercury switch sets off the alarm whenever the housing is displaced horizontally. If a pressure-sensitive activation is desired, the housing can be attached to the object so that the housing supports the weight thereof. When the object is moved, the mechanical switch activates the alarm signal at the remote receiver.

While only one embodiment of the present invention has been shown and described, it will be obvious to those persons or ordinary skill in the art that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.

What I claim is:

1. A distress call signalling circuit, for transmitting a distress signal to a remote receiver which detects the distress signal and generates an alarm, comprising:

a battery;

a transmitter, having one of its terminals coupled to said battery, for .generating a signal at a specified frequency;

' a capacitor, having a predetermined breakdown voltage,coupled at one end to said battery and at the other end to the other one of said transmitter terminals;

a mercury switch, coupled in parallel to said capacitor, and having at least two contacts, one of said contacts being coupled to said transmitter and the other of said contacts being coupled to said battery; and

a pressure-sensitive mechanical switch, coupled in parallel to said capacitor, and including a stationary contact and a pair of movable pressuresensitive contacts diposed adjacent said stationary contact, said stationary contact being coupled to said battery, and said movable contacts being coupled to said transmitter.

2. The circuit as recited in claim 1, further comprising a second battery, coupled in parallel to said first battery, and a switching member, coupled in series with said first and second batteries, and responsive to the voltage output of said first battery, for coupling said transmitter to said second battery when said voltage output of said first battery falls below a predetermined level.

3. The circuit as recited in claim 2, wherein said switching member comprises a relay.

4. The circuit as recited in claim 1, wherein said mercury switch comprises a mercurytoroid tube switch.

Claims (4)

1. A distress call signalling circuit, for transmitting a distress signal to a remote receiver which detects the distress signal and generates an alarm, comprising: a battery; a transmitter, having one of its terminals coupled to said battery, for generating a signal at a specified frequency; a capacitor, having a predetermined breakdown voltage,coupled at one end to said battery and at the other end to the other one of said transmitter terminals; a mercury switch, coupled in parallel to said capacitor, and having at least two contacts, one of said contacts being coupled to said transmitter and the other of said contacts being coupled to said battery; and a pressure-sensitive mechanical switch, coupled in parallel to said capacitor, and including a stationary contact and a pair of movable pressure-sensitive contacts diposed adjacent said stationary contact, said stationary contact being coupled to said battery, and said movable contacts being coupled to said transmitter.

2. The circuit as recited in claim 1, further comprising a second battery, coupled in parallel to said first battery, and a switching member, coupled in series with said first and second batteries, and responsive to the voltage output of said first battery, for coupling said transmitter to said second battery when said voltage output of said first battery falls below a predetermined level.

3. The circuit as recited in claim 2, wherein said switching member comprises a relay.

4. The circuit as recited in claim 1, wherein said mercury switch comprises a mercury toroid tube switch.

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