GB2251106A - Multi-point detection systems - Google Patents

Abstract

A centralised monitoring unit for a multi-point detection system, e.g. nurse call or intruder detection system, comprises a data input/output unit 22 for connection to a plurality of detectors, such as a nurse call station 23, in daisy-chained manner, to permit an addressing unit 27 to supply a respective interrogation signal to each detector in turn, responses causing code numbers indicative of actuated detectors to be displayed 3. <IMAGE>

Description

''Multi-Point Detection Systems" This invention relates to multi-point detection systems and centralised monitoring units therefor, such as are used for nurse calling in a hospital, for example, or in various security applications, or in data collection.

In hospitals it is usual for a respective call button to be installed in the vicinity of each patient bed to enable a patient to obtain nursing assistance without leaving the bed. Each such call button is connected separately to a centralised monitoring unit, and the monitoring unit provides an indication of the button which has been actuated so as to enable a nurse to give assistance to the appropriate patient. Additionally the system may include visual indicators at the entrance to a ward or at the location of a patient's bed to provide a further indication of the location of the patient making the call.

However conventional nurse call systems are costly to install, as well as being relatively inflexible in use. This is because each call button must be separately wired to the centralised monitoring unit, and any appreciable change in use of the system will generally require extensive re-wiring.

It is an object of the invention to provide a multi-point detection system which is particularly adapted for use as a nurse call system and which can be installed at lesser cost than existing systems.

According to the present invention there is provided a centralised monitoring unit for a multi-point detection system, comprising data input/output means for connection to a plurality of detectors in daisy-chained manner, addressing means for supplying a respective interrogation signal to each detector in turn by way of the data input/output means, receiving means for receiving a respective response signal from each detector by way of the data input/output means in response to receipt of an interrogation signal from said addressing means, detector mode sensing means for determining the mode of each detector from the form of the associated response signal received by said receiving means, and indicating means for supplying a predetermined indicating signal indicative of actuation of one or more of the detectors of said sensing means.

The expression "in daisy-chained manner" means in this context that the connecting wire is connected in sequence to the first detector, then from the first detector- to the second detector, and so on, without it being necessary for a separate wire to be connected from the monitoring unit to each detector.

Since the detectors are connected in daisychained manner to the data input/output means of the centralised monitoring unit, only a single cable, including a data line, a control line and generally two power supply lines, is required for connection of the detectors to the monitoring unit.

Of course it may be convenient, depending on the building layout, for some of the detectors to be provided on spur or tee connections to the main circuit.

Preferably the indicating means includes a visual display for indicating a code representative of the or each detector which has been actuated. The indicating means may also include an audible alarm for indicating when one of the detectors has been actuated.

Furthermore the indicating means may be adapted to indicate on the visual display two or more codes representative of two or more detectors which have been actuated, each code being indicated for a predetermined length of time and the codes being indicated on a cyclic basis.

Additionally the indicating means may include recording means, such as a printer or a memory, for providing a record of the detector which has been actuated and the time at which the detector has been actuated.

It is also preferred that the unit includes clearing means which is adapted to clear any indicating signal in response to the manual operation of a resetting switch. In the case of a nurse call system a respective resetting switch may be associated with each nurse call button so that the indication is only cleared by manual operation by the nurse visiting the patient's bed to answer the call. Where the indicating means includes recording means, the clearing means may also be adapted to cause the recording means to provide a record of the time at which the indicating signal has been cleared.

Furthermore the unit may include acceptance means which is adapted to cause the indicating means to indicate acceptance of an indicating signal in response to manual operation of an accept switch. In the case of a nurse call system the accept switch may be centrally located so that it may be operated to indicate acceptance of a call prior to a nurse being despatched to a patient's bed to answer the call.

Where the system is used as an intruder detection system, the clearing means may be adapted to disable one or more of the detectors, such as a detector safeguarding an entrance to a building, for a predetermined period of time on receipt of a manually entered code.

The monitoring unit may also include zone control means for controlling the supply of interrogation signals to the detectors by the addressing means so as to enable interrogation signals to be supplied to only some of the detectors when the unit is to be used for monitoring only a restricted zone within the system.

The invention also provides a multi-point detection system comprising a centralised monitoring unit as defined, and a plurality of detectors connected to the data input/output means of the centralised monitoring unit in serial manner In order that the invention may be more fully understood, a multi-point detection system in accordance with the invention will now be described, by way of example, with reference to the accompany drawing, in which: Figure 1 is an explanatory diagram illustrating possible applications of the system; Figure 2 is a block circuit diagram of the system.

Referring to Figure 1 the system comprises a centralised monitoring unit 1 incorporating a keypad 2, a light-emitting diode or liquid crystal display 3 and a matrix printer 4. The monitoring unit 1 is mains powered, although it has a rechargeable battery backup 5 for use in the event of power failure. The monitoring unit 1 can be connected to up to 254 detector outstations by means of four core telephone cables. In the illustrated embodiment there are two circuits 6 and 7 each of which has up to 127 outstations connected in daisy-chained manner. However it should be understood that it would also be possible to provide only a single circuit incorporating all the outstations connected in daisy-chained manner.

Each cable is connected to an outstation connector box 8 from which a connection lead runs to the associated detector switch, and a further four core cable then runs from the outstation to the next outstation in the circuit. The connector box 8 incorporates electronic logic to provide a response signal indicative of the mode of the associated detector switch in response to receipt of an interrogation signal from the monitoring unit addressed to that outstation. For a nurse call outstation the detector switch may be incorporated in a push button connected to the outstation by a two core lead. In other applications a four core lead may be used to connect the detector switch to the outstation, two of the connecting wires being used for an anti-tamper circuit in a security application.

Depending on the initial set-up of the system, the monitoring unit 1 may serve to monitor the detection mode of various types of detector which have been activated deliberately, as by a patient in a nurse call system, or accidentally, as by an intruder in an intruder detection system. Thus, for example, the circuit 6 may incorporate a plurality of nurse call outstations 10, each of which comprises a panel 11 to which a push button 12 is connected by a lead. The panel 11 is fitted with a light-emitting diode which indicates when the button 12 has been actuated by the patient, and a reset button which may be operated by the nurse to clear the call indication from the monitoring unit display 3.Other types of outstation may also be provided on the circuit 6 for simultaneous monitoring with the nurse call outstations, such as a passive infrared detector outstation 13 or a window open detection outstation 14. Further outstation detectors may be connected to the circuit 7, such as a float-operated switch outstation 15 for detecting overflow of a water storage tank or a temperature-operated switch outstation 16 for detecting malfunction of a central heating boiler or a door operated switch outstation 17 for detecting an intruder.

Where any movement of a patient out of a bed or from a room is to be monitored, it is also possible for the system to incorporate a pressure operated-switch arranged so that it is actuated when the patient steps out of bed and/or a door-mounted switch arranged to be actuated when the patient leaves the room. The monitoring unit 1 may also be connected to an external audible alarm 18 to provide an audible warning in the event of actuation of a detector.

The operation of the monitoring unit 1 will now be described in more detail with reference to use in a nurse call system, it being understood that this is only one application of the unit 1, and other applications are possible with suitable initialisation of the unit.

Referring to Figure 2, the monitoring unit 1 has a data input/output unit 22 for connection to the nurse call stations 23 by a line 24, and a read/write control unit 25 for connection to the nurse call stations 23 by a line 26. The lines 24 and 26 form two of the conductors of a four core cable, the other two conductors (not shown in Figure 2) being the power supply lines for supply of power from the monitoring unit 1 to the call stations 23.

Although the following description will be given with reference to operation of the monitoring unit 1 in response to actuation of the call buttons at the nurse call stations, it will be understood that the monitoring unit 1 will also provide similar indications in response to triggering of other detectors which may be incorporated in the system.

Each call station 23 is allocated a distinctive address which may be imparted to the station by physically removing one or more circuit connections on a printed circuit board forming part of the station during installation (or alternatively by setting of switches provided for that purpose), and each call station 23 is interrogated twice by supplying an address signal from an address unit 27 by way of the data input/output unit 22.

Each call station 23 is interrogated twice every two seconds by the address unit 27, and in response to such addressing supplies a response signal to a receiving unit 28 by way of the data input/output unit 22. The form of the response signal is dependent on the mode of the call station 23, that is whether or not the call button has been operated by the patient, and this is sensed by a detection mode sensor 29. The same line 24 is used for both interrogation and response signals, and control of the transmission of such signals is exercised by the read/write control unit 25.

In the event that operation of a call button by a patient is detected, the detection mode sensor 29 supplies a signal to a control unit 30, and the control unit 30 causes a code number indicative of the call station 23 actuated to flash on the display 3 and also causes an internal alarm 31 to buzz. Additionally the control unit 30 operates the printer 4 so as to provide a permanent record on paper of the code number of the call station 23 actuated and of the time of actuation.

The receipt of the call is then acknowledged by a nurse pressing an ACCEPT key on the keypad 2, and this then causes the control unit 30 to change the indication provided by the display 3, for example by causing the appropriate code number to be displayed continuously, and to deactivate the alarm 31. The operation of the ACCEPT key indicates that action is to be taken to answer the call, either by the nurse who has operated the key visiting the patient, or by a message being sent to another nurse over a paging system. Additionally, on the nurse arriving at the patient's bed, the nurse will operate the reset button on the panel of the associated call station 23 so as to deactivate the station and, as a result, so as to cause a clearing signal to be supplied by the detection mode sensor 29 to the control unit 30.In response to receipt of such a signal the control unit 30 causes indication of the code number by the display 3 to cease, and at the same time causes the printer 4 to provide a record of the code number of the call station 23 which has been deactivated and the time at which the station has been deactivated.

The control unit 30 may also provide simultaneous indication on the display 3 of actuation of more than one call station 23 by indicating the code number of each station for a period of two seconds (either in flashing mode or in a continuous mode depending on whether the ACCEPT key has been pressed), the code numbers being indicated sequentially on a cyclic basis. This enables a decision to be made on which call is to be answered first on the basis of which is the most important call to be attended to.

It is also possible for the system to include an emergency call facility. In this case a second outstation provided with a push button and associated red and green lights will be located near to or outside the door to the patient's room, in addition to the outstation at the patient's bed which in this case will not have a reset button. In the event that the push button associated with the patient's outstation is pressed, the centralised monitoring unit will react in the manner already described, and also the red light at the door will be illuminated so as to provide a local indication of the need for nurse assistance. On responding to the call, the nurse will press the push button on the door outstation, thus cancelling the red light on both patient and door outstations and lighting the green light. Thus operation of the door outstation by the nurse has a similar function to operation of the reset button as previously described, and sends the required clearing signal to the monitoring unit. The lighting of the green light at the door outstation provides a local indication that a nurse is in attendance on the patient. On leaving the room the nurse pressed the push button on the door outstation to cancel the green light.Should additional assistance be required by the nurse while in attendance on the patient, the nurse may press the button on the patient outstation and, due to the fact that nurse attendance has already been registered, this will provide a flashing indication on the display of the monitoring unit, and will at the same time initiate urgent audible warning both on the monitoring unit and on localised floor display provided for this purpose.

In addition the control unit 30 includes a battery-backed random access memory for storing initialisation data in relation to the outstations and data indicative of the last thousand operational events detected by the system. Thus, in the event of loss of the previously printed record or for any other reason, it is possible for a printout to be obtained of the codes and times associated with the last thousand events by entry of a password into the control unit 30 using number keys on the keypad 2. Furthermore the control unit 30 is also responsive to the entry of codes on the number keys of the keypad 2 in order to remove one or more selected call stations 23 from the stations interrogated by the address unit 27.This enables zone control to be exercised so that only those call stations 23 having patients assigned to them are monitored by the centralised monitoring unit 1, for example. In the event of a call station being put into or taken out of the scan cycle of the address unit 27 in this manner, the control unit 30 causes the printer 4 to provide a printed record of the event. The unit 1 also includes a RS 232 data link (not shown) for communication to an external printer or computer system.

Furthermore, in the event of a fault, such as a break in a cable or a detector failure, the control unit 30 will provide a visual indication on the display 3 and a printed record on the printer 4 indicative of the location of the fault. If required, internal relays in the unit 1 may be used to operate an external alarm or paging system, and the RS 232 data link may be used to operate a digital communicator.

The control unit 30 may also be set up to display a further code on the display 3, such as a single letter, indicating the type of detector which has been actuated and/or the identity of the nurse allotted to the patient at the call station actuated.

During initialisation of the system the following parameters may be allotted within the system after entering the engineers system initialisation mode by pressing a PASS key and entering a four digit code on the keypad.

1. A code number may be allotted to each outstation by pressing the number keys followed by an ENTER key, together with an indication as to whether the station is to be excluded in (IN key) or excluded from (OUT key) the system.

2. The mode of each outstation, either normally closed or normally open, corresponding to the non-alarm state may be set by the IN or OUT keys.

3. Each outstation may be designated as either a security or nurse call type by operation of the IN or OUT key.

4. Each outstation may be allotted to a particular zone by entering a zone number and pressing an ENTER key.

5. Each outstation may be allocated to a particular room number, and if required a particular subroom number,in a similar manner to the zone allocation.

6. A particular outstation may be allocated to the entry/exit route for an intruder detector system.

7. The internal clock may be set by using the IN and OUT keys to advance or retard the clock.

The various selection modes are entered by pressing different number keys, and the initialisation mode is terminated by pressing the PASS key.

Although the description of the unit 1 with reference to Figure 2 has been made in relation to defined circuit blocks, it should be understood that in practice the functions of more than one such circuit block may be undertaken by a simple circuit element, such as a central microprocessor under the control of an EPROM.

The described monitoring unit may also be used in an intruder detector system for monitoring unauthorised entry into a building as detected by a series of intruder detector connected to the unit. In this application one of the outstations will be located at the main exit/entry to the building, this outstation comprising a door sensor, for example, and the monitoring unit is not normally manned. Authorised entry to the building is gained by use of a key switch or similar device which disables the exit/entry outstation for a predetermined period allowing sufficient time for access to be gained to the monitoring unit to enable it to be unset by entry of a password or code on the keypad. Similarly the system may be reset by entry of a password or code on the keypad, and the exit/entry outstation will be disabled for a predetermined period of time after such resetting to allow exit from the building.

Claims (12)

Claims

1. A centralised monitoring unit for a multi-point detection system, comprising data input/output means for connection to a plurality of detectors in daisy-chained manner, addressing means for supplying a respective interrogation signal to each detector in turn by way of the data input/output means, receiving means for receiving a respective response signal from each detector by way of the data input/output means in response to receipt of an interrogation signal from said addressing means, detector mode sensing means for determining the mode of each detector from the form of the associated response signal received by said receiving means, and indicating means for supplying a predetermined indicating signal indicative of actuation of one or more of the detectors of said sensing means.

2. A unit according to Claim 1, wherein the indicating means includes a visual display for indicating a code representative of the or each detector which has been actuated.

3. A unit according to Claim 2, wherein the indicating means includes an audible alarm for indicating when one of the detectors has been actuated.

4. A unit according to Claim 2 or 3, wherein the indicating means is adapted to indicate on the visual display two or more codes representative- of two or more detectors which have been actuated, each code being indicated for a predetermined length of time and the codes being indicated on a cyclic basis.

5. A unit according to any preceding claim, wherein the indicating means includes recording means for providing a record of the or each detector which has been actuated and the time at which the or each detector has been actuated.

6. A unit according to any preceding claim, which includes clearing means adapted to clear any indicating signal in response to the manual operation of a resetting switch.

7. A unit according to Claim 6 for a nurse call system including a plurality of nurse call buttons, wherein a respective resetting switch is associated with each nurse call button to enable the associated indicating signal to be cleared by manual operation of the resetting switch by a nurse visiting the patient's bed to answer a call.

8. A unit according to any preceding claim, which includes acceptance means adapted to cause the indicating means to indicate acceptance of an indicating signal in response to manual operation of an accept switch.

9. A unit according to Claim 6 for an intruder detection system, wherein the clearing means is adapted to disable one or more of the detectors for a predetermined period of time on receipt of a manually entered code.

10. A unit according to any preceding clalm,- uhich includes zone control means for controlling the supply of interrogation signals to the detectors by the addresSínW to only some of the detectors when the unit is to be used for monitoring only a restricted zone within the system.

11. A multi-point detection system comprising a centralised monitoring unit according to any preceding claim and a plurality of detectors connected to the data input/output means of the centralised monitoring unit in daisy-chained manner.

12. A centralised monitoring unit for a multi-point detection system, substantially as hereinbefore described with reference to the accompanying drawing.