Abstract:
Sensor means for monitoring the awareness status of an individual within a monitored environment ( 50 ) comprising means ( 55 ) for determining the attainment of at least one predetermined condition identifying the requirement for the awareness of an individual to be monitored, and operative to trigger an alarm ( 70 ), means ( 15 ) operable by the monitored individual for inhibiting the operation of the alarm, and delay means for delaying the triggering of the alarm ( 70 ) for a predetermined period after the attainment of the said predetermined condition.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a safety device and particularly to a safety device for use in situations where it is necessary to maintain consciousness or at least awareness. Such situations include, without limitation, those where an individual at risk may be otherwise unsupervised. 
   2. Description of the Related Art 
   In a hospital or like environment it is important that the consciousness or awareness status of an individual is known to the staff. This is of the utmost importance in connection with patients whose state of health is uncertain, such as patients undergoing tests, those in hospital for observation or those convalescing or recovering from an operation. However, there are situations where a patient is not usually supervised, for example, toilet cubicles or washing facilities. If a patient falls ill and becomes unconscious or partly conscious whilst unsupervised in these situations it may be some time before they are found and located so that their condition can be attended to. 
   Toilet cubicles are particularly relevant in the case of people at risk of cardiac arrest, major pulmonary embolus or hypoglycaemia. It is known that many people have a circulatory arrest whilst in a toilet. This is not coincidental but rather, at least in part, because the vagal reaction makes them think that they need the toilet when it may in fact be an early response to the events leading to the collapse. 
   There are, of course, other circumstances where consciousness or awareness indications are required. For example it has long been the practice to provide the driver&#39;s cab of a railway locomotive with a device known as a “dead man&#39;s handle” which is to be maintained in an operative state by the train driver in order to ensure that he has not fallen asleep as a result of the essentially tedious nature of this task. 
   Some toilets and bathrooms are provided with emergency cords which must be pulled to trigger a signal to attract attention. However, it may not always be possible for the patient to pull such a cord, for example because they have fallen on the floor and/or are unconscious, or because they have become disorientated or confused as a result of a medical condition. 
   There exists the need for a device which requires a patient to do something positive to demonstrate that they do not need assistance. 
   Accordingly, the present invention provides sensor means for monitoring the awareness status of an individual within a monitored environment, comprising means for determining the attainment of at least one predetermined condition identifying the requirement for the awareness of an individual to be monitored, and operative to trigger an alarm, means operable by the monitored individual for inhibiting the operation of the alarm, and delay means for delaying the triggering of the alarm for a predetermined period after the attainment of the said predetermined condition. 
   The monitored environment may comprise an enclosed space. In a preferred embodiment the safety device is designed for use in a lavatory cubicle; however, other situations where individuals are not normally supervised, such as bathrooms or shower cubicles, are not beyond the scope of the invention. 
   The condition identifying the requirement for the awareness of an individual to be monitored may be no more than the presence of the individual in the monitored environment. 
   The means for detecting the presence of an individual may act either indirectly, for example by sensing operation of a door lock, or by remote sensing means sensitive to the presence of an individual within a range thereof, such as an infra red or other light beam or an ultrasonic detection means. In any case it is preferable that the individual cannot be present in the monitored environment without being detected. In the case of a door lock for a toilet it is therefore preferable that the associated door is biased to be open, by any suitable means, such as a spring. The lock is then required to hold the door closed so that an individual will be encouraged by this so not use the toilet without locking the door, and in doing so identify the requirement for him or her to be monitored. 
   In an alternative embodiment the device itself may be attached to or worn by a monitored individual and set to detect when the individual enters an otherwise unsupervised environment, for example a stairwell where visual monitoring by staff is not available. When in this environment, the user must maintain a button pressed or provide other awareness indication to prevent triggering of an alarm. 
   The positioning of the means for inhibiting the alarm within the monitored environment and its operation is preferably dictated at least in part by ergonomic considerations, so as to be accessible, comfortable and not inconvenient for the monitored individual to use. The means for inhibiting the alarm may be fixed in its position or movable to a limited extent to allow positioning for convenient use by a user regardless of his or her position in the monitored environment. Likewise all, or part of the means for inhibiting the alarm may be adjustable for the comfort and convenience of the monitored individual. 
   The means for inhibiting the alarm may be formed so as to be operable whilst a monitored individual is seated or standing and may be operable for example by a limb, hand, foot or digit, the general principle being that the action must be one requiring sentient control. 
   In a preferred embodiment the means for inhibiting the alarm is a push button pressed by a foot. However other suitable arrangements such as a pedal or hand-operated lever or one positioned to be operated by a knee, or a switch to be operated by a digit are not beyond the scope of the invention. 
   In a preferred embodiment the means for inhibiting the alarm is a push button which is located on the floor and is upstanding therefrom. It may be preferable, however, for the means for determining the attainment of a predetermined condition and/or the means for inhibiting the alarm to comprise a member which does not protrude substantially above the level of an associated surface so as not to present a risk of tripping. For example the member may comprise a laminar element such as a pressure pad to be placed on the floor whereby to be substantially level therewith, a membrane switch or a sunken button. A laminar element may be sensitive to pressure over part of its surface; markings or other visible indicia such as coloured areas may be provided to identify the required position of the user&#39;s feet or other actuating member. 
   For the visually impaired tactile indicators may be provided, such as surface roughening or small projections. 
   This principle could also be applied to the means for determining the requirement for monitoring the individual. For example a pressure pad or membrane switch could be positioned at the entrance of the monitored environment so as to be triggered as the individual enters. 
   The means for inhibiting the alarm may be resiliently biased to the alarm-activating position so that the bias has to be overcome by muscular effort to prevent the alarm from sounding. 
   In order to avoid the possibility that the operating limb, hand or foot may remain on the means for inhibiting the alarm following unconsciousness or illness, it is desirable for the alarm-inhibiting means to require deliberate muscular effort to maintain it in its operating position so that muscular relaxation upon loss of consciousness will result in the alarm being raised. The effort required to operate the means for inhibiting the alarm is therefore preferably more than that which could be satisfied merely by placing the weight of the limb, hand or foot on it. 
   It is preferable that the bias acts in such a way that it is unlikely that an individual could or would wish to act against it, either deliberately or inadvertently whilst in need of assistance. The required effort may be variable. 
   Although operation of the means for inhibiting operation of the alarm must be deliberate, the operation does not have to be continuous. For example, in the case of a lever which is pushed down, the lever may gradually return to its starting position, whereby the individual must periodically depress the lever to prevent activation of the alarm. 
   The means for inhibiting the alarm may further include a guard member or element which may be positioned to inhibit accidental operation. 
   In a preferred embodiment the guard comprises a U-shape raised collar and a push button is located in the recess defined therein. However, other means such as a flap or cover which must first be removed could also be envisaged. 
   The alarm may consist of audible, visual or other appropriate signals to alert the attention of supervising staff. The alarm may be localised to the area of the means for inhibiting the alarm and/or may be connected to a central monitoring system. Connection of the sensor means to the alarm and/or a central monitoring system may be direct or by telemetry. 
   The system preferably has means to avoid inappropriate activation of the alarm. For example, in the case of a toilet cubicle, in the normal course of events when an individual has finished using the toilet and wishes to leave the cubicle or wants to adjust the position of his or her foot he or she may have to release the means for inhibiting the alarm; it is undesirable for the alarm to sound immediately. This may be overcome by having a predetermined delay between such release and sounding of the alarm; any such time delay should not, however, be so long as to endanger a user with a genuine emergency. 
   Once the requirement for monitoring the individual is satisfied there may also be provided warning means which operate during the predetermined period after the attainment of this predetermined condition. The warning means will therefore be effective to serve as a reminder to operate the means for inhibiting the alarm, both initially as the individual enters the monitored environment and at any time during their occupation for example if they remove their foot to adjust its position, until the means for inhibiting the alarm are activated or the individual leaves the enclosed space. The warning means may comprise means for generating an audible; the signal may increase in frequency with time. 
   The system is preferably co-ordinated with the presence detector so that the alarm function is inactivated once the individual has left the cubicle. There may also be provided further means for deliberately inactivating the alarm function, for example a key held by a responsible person which may be used if the alarm has activated and staff are in attendance, the alarm no longer being required. 
   In the case of patients whose mental or physical state makes it unlikely or impossible for them to operate an alarm-inhibiting device requiring sentient muscular control it may be necessary or desirable to have an individual such as a healthcare auxiliary in close proximity to the monitored environment. In such cases there may be provided second means for inhibiting the operation of the alarm located externally of the monitored environment and operable by a supervisor able to maintain supervision of the monitored environment. In this case the second alarm-inhibiting means effectively ensures that the monitoring takes place. 
   To prevent the triggering of the alarm, operation of the second means for inhibiting the alarm may be required in addition to or instead of the means operable by the monitored individual. In the first case, operation of the second means could be used to ensure that the healthcare auxiliary remains in place in close proximity to the monitored environment. In the second case, operation of the second means could be used where the monitored individual, because of disability or mental state, is unable to operate the means for inhibiting the alarm, the healthcare auxiliary inhibits the alarm but is in close proximity to the monitored environment and may periodically assess their awareness, for example by speaking to the monitored individual to get a verbal response. 
   The second means for inhibiting the alarm may function in the same way as the means for inhibiting the alarm operated by the monitored individual, in that the means are resiliently biased to an alarm-activating position (such as a normally-closed switch) and require a continuous conscious action, such as pressing a button, to avoid triggering the alarm. 
   If the alarm sounds for any reason the lock of the cubicle door may automatically be opened to allow access to the individual. In hospitals this would not usually be needed because cubicles are normally equipped with means by which they can be opened from outside in an emergency. 
   The system may be retrofitted to existing enclosed spaces or installed upon initial construction. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various embodiments of the invention will now be more particularly described by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a schematic perspective view of switch means for inhibiting an alarm according to a first embodiment of the present invention. 
       FIG. 2  is a schematic view of the system of the invention in situ in a toilet cubicle; 
       FIG. 3  is a flow chart illustrating the logical steps in the operation of the sensor means according to the first embodiment of the present invention; 
       FIG. 4  is a schematic perspective view of means for inhibiting an alarm according to a second embodiment of the present invention; 
       FIG. 5  is a schematic perspective view of a system formed as a third, more comprehensive, embodiment of the present invention in situ in a toilet cubicle; and 
       FIG. 6  is a circuit diagram illustrating the main electrical components used in the system forming the third embodiment of the present invention; and 
       FIG. 7  is a schematic perspective view of a system formed as a further embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring first to  FIG. 1  there is shown switching means generally indicated  10  for use in a system for inhibiting an alarm. An upwardly projecting foot-operated push-button  15  is positioned in the recess defined by a generally U-shape guard  20 . The guard  20  is a raised collar which partly surrounds the push-button  15  and serves to prevent accidental depression thereof. The collar stands up from a base  11  which houses the switch components and is connected to the circuit by a cable  12  allowing the switch to be positioned comfortably for the user. 
   The push-button  15  is resiliently biased to the raised alarm activating position as shown in  FIG. 1 , and requires a user to apply pressures through his or her foot, such as by a heel  40  to depress it. The switch may alternatively be depressed by a toe. 
   Referring now to  FIG. 2  the main components of a system for monitoring a toilet cubicle generally indicated  50  are schematically illustrated. These comprise a door  60  with a lock  55  and a toilet pan  30 . When an individual enters the cubicle  50  and operates the lock  55  of the cubicle door  60 , the requirement for the awareness status of the individual to be monitored is triggered. 
   The push-button switch  15  is located adjacent the toilet  30  with the guard  20  positioned so as to prevent accidental or inadvertent depression of the pedal  15  by an individual present in the cubicle  50  in the vicinity of the toilet  30 . 
   The switch operated by the pedal is closed when the pedal  15  is in the raised position so that, if left in this position, it will cause the alarm  70  to be activated after a delay period as will be described, in order to allow the individual sufficient time to adjust his or her clothes to make preparation to use the toilet. Once the individual is otherwise ready to use the toilet  30  the push-button  15  is depressed and maintained in the depressed state by deliberate pressure from the foot of the individual to prevent activation of the alarm  70 . 
   Referring now to  FIG. 3  there is shown a flow-chart illustrating the logical steps in the operation of the system of the invention. It will be appreciated that this is a schematic representation of the underlying logical steps and not a representation of the implementation of  FIG. 1  or  2 . 
   In the normal or monitoring state of the system it checks continuously whether an individual is present in the monitored environment. Whilst the answer to this question is “no” the system operates continuously in order to maintain a monitoring check on the environment. With the operation of the door lock  55  the necessary requirement for indication that an individual is present is met; after a predetermined delay the system checks whether the push-button  15  has been depressed by the individual. If the answer to this question is “no” the alarm is triggered. 
   If the push-button has been depressed by the user within the delay period the answer is “yes” and after a further short delay (of a few seconds) the system checks again that the push-button is still pressed. 
   So long as the answer to this question is “yes” a continuous loop operates repeating the check every few seconds. 
   When the pedal  15  is released, either because the individual is in need of assistance or is simply in the process of leaving the cubicle  50 , the response to the monitoring check will indicate that the push-button is not still depressed. Then, after a predetermined delay the system checks if the individual is still present (indicated by the same means  55  as initially detected this status as discussed above). If the answer to this question is “no”, the individual has left the cubicle  50  and the system returns to the initial state to maintain a monitoring check for the arrival of a new occupant. If the answer to this question is “yes” this indicates that the individual may be in need of assistance and the alarm  70  is immediately activated. 
   Referring now to  FIG. 4  there is shown alternative switch means suitable for use in inhibiting an alarm, generally indicated  110 . This switch is suitable for permanent fixing to the floor of a monitored environment. A generally L-shape guard  120  comprises lower column or support  130  from which a transverse arm  135  projects laterally. The support  130  extends substantially vertically from the ground. At the upper end of the support  130  the transverse arm  135  extends generally orthogonally to form the L-shape guard  120 . Within the included angle defined by the guard  120  a trigger lever  115  depends from the transverse arm  135 . In use the foot  140  of an individual is introduced under the transverse arm  135  to reach the trigger lever  115  which is then pushed laterally in the direction shown by the arrow A towards the support  130  to the position shown in phantom outline to inhibit the alarm. The force required to maintain the button depressed will require that if the user loses consciousness and experiences muscle relaxation the trigger lever  115  will more back to its original position and trigger the alarm as discussed above. 
   Referring now to  FIG. 5  the main components of a second embodiment monitoring system for a toilet cubicle generally indicated  250  are schematically illustrated. These comprise a door  260  with a lock  255  and a toilet pan  230 . The door  260  is resiliently biased to an open position by the operation of a spring  265  illustrated only schematically, and will therefore not remain closed unless the door is held shut, for example by operating the lock  255 . When an individual enters the cubicle  250  and operates the lock  255  of the cubicle door  260 , the requirement for the awareness status of the individual to be monitored is triggered. 
   In this embodiment the switch means for inhibiting the alarm are formed as a portable unit generally indicated  210  similar to that in  FIG. 1 . A generally semi-circular guard  220  has a raised collar defining a U-shape recess. In this embodiment the guard  220  is made of rubber so as to be durable and hard-wearing. A push button  215  is positioned in the U-shape recess of the guard  220  for opening a switch within the body of the device. 
   The switch means  215  are kept closely adjacent the toilet pan  230  and are in contact with the necessary components of the sensor device via a wire  240 . In other embodiments (not shown) a remote (i.e. wireless) link may be used. 
   The push button  215  is shown in the raised, alarm-activating position and if left in this position will cause an alarm  270  to be activated after a delay period as will be described, in order to allow the individual sufficient time to adjust his or her clothes to make preparation to use or leave the toilet  230  or adjust his or her foot during use. Once the individual is otherwise ready to use the toilet  230  the push-button  215  is depressed and maintained in the depressed state by deliberate pressure from the foot of the individual (not shown) to prevent activation of the alarm  270  as before. The system also includes second means for inhibiting the alarm indicated  290  located outside the toilet cubicle  250 . The second means  290  is preferably a hand-held switch having a push-button  295  which is resiliently biased to the alarm activating position. 
   The delay period defines a period of time during which the requirement for monitoring the individual is satisfied and the push button  215  is not depressed but the alarm  270  is not activated. During this time an alert  280  sounds to serve as a reminder to the individual that the push-button  215  needs to be depressed or else the alarm  270  will be activated. 
   The alert  280  produces an audible signal which increases in frequency with time. 
   The second means  290  is located outside the toilet cubicle  250  so as to be operable by an attendant. The push-button  295  must be depressed at all times the occupant remains within the cubicle if he or she is unable to press the button  215  this prevents the attendant from leaving the immediate area. The attendant must thus remain in close proximity to the monitored individual and may periodically determine the awareness of the monitored individual, for example by verbal contact. 
   Referring now to  FIG. 6  there is shown a circuit diagram illustrating the components required for the operation of the third embodiment of the invention. 
   The circuit comprises a door lock switch  345  operated by the door lock  255 , an alarm-inhibiting switch  346  operable by the push button  215 , an external alarm inhibiting switch  390  operated by the hand held unit  290 , a delay circuit  348 , an alarm  370 , an alerting circuit  380 , a relay  347 , an alarm cancel switch  349 , a master alarm cancel switch  350  and a warning light  360 . 
   The door lock switch  345  is a normally open switch and is closed by the operation of the door lock  255  (of  FIG. 5 ). 
   The external alarm inhibiting switch  390  is a normally closed switch and can be opened by operation of the push-button of the hand unit  290  (shown in  FIG. 5 ) by an attendant. 
   The alarm inhibiting switch  346  is a normally closed switch and can be opened by operation of the push-button  215  (shown in  FIG. 5 ) by the monitored individual. 
   The switches  345 ,  390 ,  346  are all connected in series, such that when the door is locked and neither of the push-buttons  290 ,  215  are opened a current will flow to the delay circuit  348 . 
   The delay circuit comprises a resistor  348   a , a diode  348   b  in parallel with it and a capacitor  348   c  which is connected between the resistor  348   a  and a ground line  381 . 
   If all three switches  345 ,  346 ,  390  are closed current flows through the resistor  348   a  and charges the capacitor  348   c  to produce a steadily increasing voltage at the alerting circuit  380  and the relay  347 . The alerting circuit thus produces an audible signal the frequency of which, being voltage dependent, gradually increases. 
   The relay  347  comprises a coil  347   a  and relay contacts  347   b . When the voltage from the delay circuit  348  reaches a threshold level the current through the coil is sufficient to close the relay contacts  347   b  and the alarm  370  is activated. 
   The relay  347  is self-latching in that, when the switch  347   b  is closed current also flows via a diode  349   a , through a normally closed alarm cancel switch  349  to the coil  347   a . With this loop active, the switch  347   b  will remain closed even if any of the switches  345 ,  390 ,  346  are then opened to stop the current flowing through the delay circuit, because the alarm cancel switch directs current through the coil  347   a  irrespective of the status of these switches  345 ,  390 ,  346 . If all of the switches  345 ,  390 ,  346  are closed, operating the alarm cancel switch  349  will not stop the alarm  370 . However, if one or more of the switches  345 ,  390 ,  346  are opened again, indicating that there is not in fact an emergency, the alarm cancel switch  349  can then be operated to stop the alarm  370 . 
   When an alarm condition exists and the alarm  370  is active, a key-operated master alarm cancel switch  350  is operable to stop the alarm  370  to allow remedial or resuscitation work to be carried out without the added stress of the alarm sounding throughout this procedure. However the switch  350  is a changeover switch so that when the alarm  370  is stopped in this way a warning light  360  is illuminated to indicate this fact, and to alert staff to the need to reset the equipment when the current emergency is over. 
     FIG. 7  shows further embodiment having alternative means for identifying the requirement for monitoring an individual, and alternative means for inhibiting the operation of the alarm. A toilet cubicle is generally indicated  450  and comprises a door  460  with a lock  455  and a toilet  430 . A pressure sensitive pad  495  is located on the floor immediately adjacent the door  460 . The pad  495  is a laminar element which does not, therefore, present a risk of tripping. The dimensions and positioning of the pad is such that when an individual enters the cubicle  450  the requirement for the awareness status of the individual to be monitored is triggered. A second pressure sensitive pad  496  is located on the floor adjacent the toilet  430  again the pad is a laminar element and does not present a risk of tripping. 
   Markings  497  define an area on which the user&#39;s feet are to be placed; the pad can be moved to allow it to be positioned comfortably for the user. Within the pad  496  defined by the markings  497  are switches  498  (shown schematically). The switches  498  are operated by pressure and are identical in function to the pedal  15  already described in relation to  FIG. 1 . 
   The mere presence of the markings  497  and the requirement to place the feet in predetermined positions represents a first level of monitoring of awareness as this act requires a conscious effort. A second level is achieved by the requirement for pressure to be exerted and maintained upon the switches  498 . 
   In addition, in this embodiment the area of the pad  496  not occupied by the markings  497  is an ‘exclusion zone’, as defined below. 
   An important feature of this embodiment is that, in addition to pressure being required on the markings  497  to inhibit the alarm, it is also a requirement that there is no pressure on the remainder of the pad  496 —the exclusion zone  499 . This is to remove the possibility that an individual falls and yet remains in contact with one or both of the markings  497 . Therefore, contact on the markings  497  inhibits the alarm  470 , whilst contact on markings and the exclusion zone does not. The exclusion zone  499  overrides the inhibitory effect of the markings  497 .