PATIENT ALERT LOCATOR

Abstract: Apparatus, for identifying an individual, e.g. a patient (10), and for detecting if that individual has improperly left a place of confinement, such as a health facility. Generally, the identification and detection (30, 40, 50) apparatus utilizes a detectable element, e.g., a magnetic strip (351) which acts as a flux-gate device or a computer controlled transceiver, into an object worn by the individual, e.g. an identification wrist band (30), a pendant, or a badge. A transmitter (52) generates an interrogating field into a localized area. The detectable element generates a response, e.g. harmonics of the interrogating field from the magnetic strip or a response message from the transceiver. This response is detected by a receiver (54) which, in turn, triggers an annunciator (95).

Description: PATIENT ALSRT LOCATOR Technical Field of the Invention - The invention relates to identification and detection apparatus and, more particularly, to apparatus for identifying and detecting an individual at a particular location without that individual's knowledge. Background of the Invention - People are often confined to a particular health facility such as, for example, a hospital or a mental facility for a certain period of time. Health facilities all share a common problem: some of the patients prematurely leave before completing their Q treatment and without first receiving permission to leave from an appropriate medical authority at the facility, e.g. their doctor or the like. For many patients who have full mental 5 capacity and are hospitalized for surgical procedures or for various tests, such premature departure, often against their doctor's order, poses a danger only to the health of the particular patient. Of these patients who prematurely leave, a certain number are Q spotted by medical personnel as they attempt to leave the facility and are restrained, if only for a short period of time, from doing so. During this time, medical personnel advise the patient against prematurely leaving and present all known adverse - consequences that may arise to the patient if he prematurely leaves. If the patient still insists on leaving, the facility usually has the patient sign appropriate consent forms indicating that the patient is aware of the risks associated with prematurely leaving, is nonetheless leaving against medical advice and assumes all the risks associated- therewith. Ostensibly, these consent forms, predicated upon the fact that the patient fully comprehends his present situation and is making a fully informed decision thereon, operate to limit the liability of the hospital to the patient in the event the patient suffers any of the adverse consequences previously disclosed to him by the hospital. However, many patients who are hospitalized for mental disorders do not possess full mental capacity. These mental patients frequently pose a danger not only to themselves but also to the public at large. If such a mental patient were to prematurely leave, his mental condition might be such as to cause him to inflict harm upon himself and/or members of the public with whom he happens to come into contact. For example, that patient might inadvertently and without his full realization stumble upon railroad tracks or a highway and be killed by an oncoming train or car. Alternatively, he might obtain a deadly weapon and seek out and injure someone in the public. Patients of this type simply do not have the capacity to fully comprehend their present situation and truly understand the likely consequences of their actions. As such, these patients are legally incapable of providing an informed consent for prematurely leaving. The health facility remains liable to that patient and to members of the public for any harm that patient causes either to himself or to others and regardless of any reasons that patient has to prematurely leave the facility. Thus, in instances where patients prematurely leave a health facility and do not first provide an informed consent or are legally incapable of doing so, the health facility bears a very heavy legal liability. Often, because large numbers of people routinely enter and leave a hospital or other health facility at almost all times of the day, hospital or medical personnel may not realize a patient has prematurely left until well after that patient has physically left the facility. For example, a patient may join a crowd that is walking right past a security guard at the exit of the hospital and, as a result, not be noticed by the guard. In situations of this type, the hospital or health facility bears the ultimate responsibility of first locating that patient and advising him to return and, if that patient has the mental capacity to legally provide an informed consent and insists on not returning, then obtaining such a signed informed consent against returning; or alternatively, if that patient lacks the legal capacity to give an informed consent, physically retrieving that patient and then properly confining him. In an effort to quickly distinguish patients from other individuals and thereby single out patients who are improperly leaving a confined area, hospitals and other health facilities frequently provide patients with some form of visual identification, usually a wrist bracelet or neck pendant, that the patient wears throughout his stay at that facility. While these visual identification devices are expendible and are thus quite inexpensive; unfortunately, the patient can often easily hide the device from others and defeat its use. For example, the patient can put his hand and the bracelet in his pocket or merely shield the bracelet from view with an appropriate object, e.g. a book or newspaper. As such, these visual identification devices have generally proven inadequate for detecting patients who prematurely leave a hospital or health facility. As such, a need has arisen in the art for detection and identi ication apparatus which can be used to readily detect and identify an individual without that individual's knowledge. A particular need has arisen for an inexpensive expendible identification device that can be used in such apparatus. Summary of the Invention - Accordingly, an object of the present invention is to provide apparatus for detecting and identifying a subject without that subject's knowledge. A specific object is to provide such apparatus that does not need to be visually perceived in order to detect the subject at a particular location. Another specific object is to provide a patient identification device for use in such apparatus which is inexpensive and expendible. These and other objects are accomplished in accordance with the principles of the present invention by concealing a detectable element, e.g. a magnetic strip which acts as a flux-gate device or a computer controlled transceiver, into an object worn by an individual, e.g. an identification wrist band, a pendant, or a badge. A transmitter generates an interrogating field into a localized area. Whenever the individual wearing the object moves through the area, the concealed detectable element generates a response, e.g. harmonics of the interrogating field from the magnetic strip or a response message from the transceiver. This response is detected by a receiver which, in turn, triggers an annunciator to alert others to the identification and location of the individual. Brief Description of the Drawing - The principles of the present invention can be readily understood by considering the following detailed description in conjunction with the drawing, in which: FIG. 1 depicts a diagram of an identification and detection system incorporating the principles of the present invention; FIG. 2 is a block diagram of the detection portion of the system shown in FIG. 1; FIG. 3 is a top view of an embodiment of the identification portion of the system shown in FIG. 1, specifically wrist band 30; FIG. 4 is a side view of wrist band 30 taken along lines 4-4 shown in FIG. 3; FIG. 5 is a side perspective view of one embodiment of identification tag 350 located within wrist band 30; FIG. 6 is a front perspective view of identification tag 350 shown in FIG. 5; FIG. 7 is a side view of identification tag 35ø taken along lines 7-7 shown in FIG. 5; FIG. 8 is a front perspective view of another embodiment of an identification tag constructed in accordance with the principles of the present invention; FIG. 9 is a cross-sectional view of identification tag 850 taken along lines 9-9 shown in FIG. 8; and FIG. 10 is a block diagram of a portion of a second specific embodiment of the patient identification and detection system shown in FIG. 1. To facilitate reader understanding, common reference numerals are used to denote identical elements common to the figures. Detailed Description - After reading the following description, those skilled in the art will quickly realize that the inventive system can be readily used to identify and detect unauthorized movement of an individual from an area of confinement in a wide- variety of different facilities. As such, this system finds use in hospitals, mental facilities, nursing homes, detention centers, prisons and other such facilities. However, for purposes of simplifying the ensuing discussion, the inventive system will be described in the context of a patient identification and detection system for use in a hospital. In general, a patient identification and detection system incorporating the principles of the present invention resembles that shown in FIG. 1. As shown, the system utilizes wrist band 30 (shown in detail in FIG. 3) worn by patient 10 in conjuction with detection equipment. This detection equipment consists of detection circuitry 50 and transmitting and receiving antennas 40. Wrist band 30, as described in detail later, includes a patient identification tag (one embodiment of which is shown in detail in FIGs. 4-7 and another embodiment of which is shown in detail in FIGs. 8-9). Detection circuitry 50, in a manner to be explained shortly, is typically positioned at the side of doorway 20 and detects the passage of the patient identification tag therethrough. In particular, in one specific embodiment to be described in detail shortly, the patient identification tag includes a strip, of pre-defined dimensions, of a magnetic material having a relatively low coercivity and a relatively high permeability. Detection circuitry 50 operating in conjunction with a well-known transmitter (see FIG. 2) , located within transmitting and receiving antennas 4ø, emits a localized magnetic field into the opening of doorway 20. This field covers substantially the entire opening of doorway 20. Lead 45 carries the output of the transmitter to a transmitting antenna located within transmitting and receiving antennas 40. The magnetic strip located within patient identification wrist band 30 is excited by the magnetic field present in doorway 20 and, in response thereto, generates frequencies at harmonics of the frequency of the exciting field. Magnetic devices of this type, which when excited by a magnetic field, generate harmonics of the exciting field are commonly referred to as "flux-gate" devices and are well-known in the art. For example, see United States Patent 2,406,870 issued to Vacquier which employs a flux-gate device in a magnetometer. Also, see United States Patent 3,790,945 issued to Fearon which discusses the optimal geometries and physical properties of a magnetic strip for use as a magnetic marker in an anti-theft system. The teachings of both of these patents are incorporated by reference herein. As discussed in these patents, by using an appropriately sized strip, generally relatively long with a very thin cross-sectional area, relatively large amplitude harmonics can be generated. Depending upon whether the exciting field has only alternating (ac) ,« or alternating and static (dc) components, a flux-gate device will * generate either only odd or both even and odd harmonics, respectively. The lowest order harmonic has the largest amplitude, with each successive harmonic having a lower amplitude than that of the immediatley preceeding harmonic. Hence, if the transmitter within detection circuitry 50 transmitted a field having both "ac" and "dc" components, the magnetic strip contained within identification wrist band 30 will produce both even and odd order harmonics, with the second harmonic having the largest amplitude. Alternatively, if the transmitter produced a magnetic field having only an "ac" component, then only odd order harmonics would be generated by the magnetic strip, with the third harmonic having the largest amplitude. In either event, a well-known receiver (see FIG. 2) located within detection circuitry 50, operating in conjunction with a receiving antenna located within transmitting and receiving antennas 40, detects one of these harmonics. Lead 42 routes signals from the receiving antenna to detection circuitry 50 and, in particular, to the receiver contained therein. Since a flux-gate device will typically generate more than one harmonic of an exciting magnetic field, the receiver — to reduce the incidence of spurious responses — could respond only to presence of multiple harmonics, e.g. the second and third harmonics given an "ac and dc" exciting field or to the third and fifth harmonics given only an "ac" exciting field. Nonetheless, whenever the desired harmonic (s) is detected by the receiver, detection circuitry 50 supplies an appropriate indication, via leads 55, to activate an annunciator located at a central site, e.g. a central reception station or guard station, situated within the hospital. This annunciator, typically a audible alarm, alerts hospital personnel that a patient wearing an identification wrist band has just transitted through doorway 20. An alarm reset switch, located at the central site provides a signal through lead 58, to reset ("re-arm") the receiver and thereby silence the annunciator until another person wearing an identi ication wrist band transits through the doorway. In addition, the receiver could be designed in a well-known fashion to silence the annunciator and re-arm itself after a given amount of time, e.g. a few minutes, has elapsed if the alarm reset switch has not been depressed during this intervening interval of time. FIG. 2 depicts a block diagram of the system shown in FIG. 1. Detection circuitry 50, as noted, contains transmitter 52 and receiver 54. This transmitter, in conjunction with transmitting antenna 43, produces the exciting magnetic field. Transmitting antenna 43 can typically have one of many different geometries, a loop or a suitable coil, of appropriate dimensions. Receiver 54, in conjunction with receiving antenna 47, receives the harmonics generated by the magnetic strip. In response thereto, receiver 54 applies an appropriate signal, via lead 55, to annunciator 95 situated within circuitry 90 located at the central site. Alarm reset switch 98, also '-located at the central site, is used to re-arm the receiver, as discussed hereinabove. FIG. 3 depicts a top view of identification wrist band 30 used in the inventive patient identification and detection system shown in FIG. 1. This wrist band is generally formed of two (or more) layers of an inert very inexpensive material, typically plastic, that have been sandwiched together and joined at their edges. Access is afforded to a space existing between these layers of plastic into which the identification tag is inserted. The top surface of the wrist band is substantially transparent to permit anyone to view the writing on the identification tag. Other suitable and similar identification wrist bands are shown and described in United States Patents 2,954,620 issued to Schneider and 3,027,665 issued to St. John. Specifically, illustrative wrist band 30 shown in FIG. 3 comprises a substantially widened section 300 which is attached at one end thereof to slender elongated section 310. Widened section 300 is substantially transparent with a slit 355 near one end thereof which provides access to rectangular space 358 located within this section. Identification tag 350 is inserted through slit 355 into space 358 so that the writing on the tag is visible through the transparent top surface of the wrist band. Once the identification tag is inserted into the wrist band, the wrist band is wrapped around a patient's wrist and then secured in place. A clasp comprised of eyelet 345 and mating pin 340 secures the wrist band around the patient's wrist. Specifically, once this band is placed around the wrist, elongated section 310 is cut to an .. appropriate length so that the length of the entire wrist band approximately matches the circumference of the patient's wrist. Thereafter, one of the holes 320 which is nearest the cut end of section 310 is placed over pin 340. The end of the wrist band with the eyelet is then folded, along hinge 330, over the pin. Thereafter, the pin is pressed through the eyelet which locks the ends of* the wrist band together and prevents the wrist band from coming off the patient's wrist. A side view of wrist band 30 taken along lines 4-4 is shown in FIG. 4. FIG. 5 is a side perspective view of one embodiment of identification tag 350 located within wrist band 30. This tag comprises two distinct portions: a identification strip 352, which carries the patient's name and other pertinent patient information such as blood type and hospital name, and magnetic strip 351. The identification strip is a slender strip of paper or plastic or other suitable material with a writing surface on one side which carries the desired patient information. Patient information can either be handwritten and/or typed onto the writing surface. Magnetic strip 351 is affixed, usually by means of a well-known adhesive, to the rear side of identification strip 352. As noted, this magnetic strip is relatively long and has a very thin cross-section. As such, the magnetic strip imparts little additional cross- sectional area to identification strip. Hence, for purposes of illustration, the cross-sectional area of magnetic strip 351 shown in the figures has been grossly exaggerated. FIG. 6 shows a front perspective view of the identification tag shown in FIG.5. FIG. 7 depicts a cross-sectional view of identification tag 350 taken along lines 7-7 shown in FIG.5. Alternatively, identification tag 350 could be formed of two laminated strips which together sandwich the magnetic strip thereby hiding the magnetic strip from- view. In this manner, the patient does not realize that the identification tag contains a magnetic strip and is thus less likely to realize that the wrist band is part of a patient identification and detection system. Such a laminated identification tag is shown in FIG. 8. Here, tag 850 contains strips 820 and 830 which together sandwich magnetic strip 351. Both strips 820 and 830 have an outwardly facing surface (e.g. surface 840 on strip 830) on which patient information can be written and as such patient information can be written on either side of identification tag 850. For that reason, the tag shown in FIG. 8 is easier to use than that shown in FIG. 5. A cross-sectional view of identification tag 850, taken along lines 9-9, is shown in FIG. 9. The system shown in FIG. 9 can be utilized to monitor the movement of a patient at home and alert others inside whenever the patient leaves the home. For example, Alzheimer patients frequently wake up during the night and wander about. Rarely, if ever, do these patients realize the risk they are taking if they leave their home. By incorporating a patient identification tag into a wrist band, or other device as described below, to the patient and monitoring one or more doorways in the home, other members of the family can be alerted whenever the patient attempts to leave the house. These family members are then in a position to stop the patient and thereby prevent any [0 resulting harm from occurring to that patient. Clearly, many other types of small slender detectable elements, other than flux-gate devices which 1 generate harmonics when excited, could be used in lieu of the magnetic strip described above. For example, a well-known passive transponder could be used in place of the magnetic strip. Such a transponder, in its simpliest form, generally comprises two resonant 20 circuits. One ciscuit, which is pre-tuned to the frequency of a locally transmitted field, receives energy from this field and, in turn, couples this energy to the second tuned circuit. The second tuned circuit oscillates at a different resonant frequency 5 and couples its energy to a small transmitting antenna located within the device which radiates this energy. The receiver would respond to the transmitted frequency and activate the annunciator. 30 A block diagram of a sophisticated patient identification and detection system incorporating the principles of the present invention is shown in FIG. 10. Here, rather than coupling a "dumb" detectable device, e.g. the magnetic strip as described is hereinabove, to the patient identification tag, an "intelligent" detectable device can be coupled instead. Specifically, as shown, identification tag 700 is no longer just a magnetic strip as depicted above, but instead comprises a computer controlled transceiver which is interrogated by detection and indentification equipment in order to detect movement through an area, e.g. a particular doorway, and identify the individuals moving therethrough. With presently available integrated circuit technology, this transceiver can be implemented using only a few chips or even just one custom large scale integrated (LSI) chip that is embedded within the identification tag, similar to that shown in FIG.9. Within this transceiver, a microprocessor system contains pre-stored medical and other pertinent patient information. The microprocessor system is connected to a transceiver which, as described in detail shortly, responds to a particular message carried on an interrogating field. Once this message is received, the microprocessor retrieves requested stored patient information and applies it to the transceiver for transmission on a carrier frequency which is the same as or different from that of the interrogating field. Detection equipment receives this message and processes the information transmitted by the identification tag in order to identify the person wearing the identification wrist band containing the transceiver system. If unauthorized individuals are moving through the area, the detection and identification system would activate the annunciator. In particular, as shown in FIG. 10, the system comprises transmitting and receiving antennas 40, detection circuitry 600, processing circuitry 800 and identification tag circuitry 700. As described hereinabove, transmitting and receiving antennas 40 and detection circuitry 600 are situated at a particular area, e.g. a doorway, to be monitored. Processing cirucitry 800 is located at a central site, e.g. a reception area or security station. Processing circuitry 800 contains a microprocessor system that operates transmitter 52, receiver 54 and annunciator 95, and display and operator controls 698. This system is also used to store pertinent information in the memory contained within patient identification tag circuitry 700 ιr In use, an identification tag is first connected to processing circuitry 800 through small well-known terminals 618. Once the identification tag is connected to processing circuitry 800, bi-directional serial communication is established between microprocessor 630 located within processing circuitry 800 and. microprocessor 720 located within identification tag circuitry 700. In response to this, microprocessor 630 signals the operator that the identification tag is ready to be programmed and then queries the operator for patient information using the display and operator controls 698. The desired information is then entered by the operator using display and operator contrpls 698 — typically a video terminal and a keyboard. Because a relatively large amount of integrated memory can be incorporated into the identification tag, significantly more information than patient name, blood type and hospital name can be entered into the memory. For example, information relating to the patient's medical affliction, allergies and medication could also be stored. In any event, display and operator control circuitry 698 routes this information over leads 675 to microprocessor 630. This microprocessor then applies this information in parallel to serial interfaces 620 via bus 628. This interface applies this information in serial form to port 2 output lead 611. From there, this information is accepted through port 1 of serial interfaces 730 located within identification tag circuitry 700. Microprocessor 720 accepts this information in parallel form, via bus 725, from serial interfaces 730 and thereafter appropriately stores this information within memory 710. Port 1 output lead 615 carries acknowledgement signals and other communication from microprocessor 720, via serial interfaces 730 and 620, to microprocessor 630. Battery 705 provides power, via lead 707, for the circuitry located within the identification tag. To conserve battery life, this battery may be connected through a well-known power switch (not shown) which is turned on just before the tag is to be programmed. Once the tag is fully programmed, the operator enters an appropriate command into display and operator controls 698. In response thereto, microprocessor 630 instructs microprocessor 720 to first activate its transceiver and then terminate serial communication with microprocessor 720. After the identification tag has been properly programmed, patient data is written or typed onto the tag and it is then inserted into a wrist band which, in the manner described above, is then secured around a patient's wrist. Transmitter 52 generates the interrogating signal which is radiated into the doorway as the interrogating field by transmitting antenna 43. This interrogating signal, rather than being a simple carrier, includes a serial digital message produced by microprocessor 630. Whenever, a wrist band containing identification tag circuitry 700 moves within the interrogating field, transceiver 750 receives the interrogating signal and the digital message generated by microprocessor 630. In response to this message, which can be a short numerical sequence, microprocessor 730 supplies an response sequence previously stored within memory 710 and instructs transceiver 750 to transmit this sequence. By 'limiting microprocessor 730 to respond only to a pre-defined numerical sequence, this markedly reduces spurious responses thereby ensuring accurate detection of patient movement. Once the acknowledgment message has been received, the identification tag and the processing circuitry have established serial radio communication therebetween. Microprocessor 630 then instructs transmitter 52 to send appropriate instructions to cause microprocessor 730 to transmit certain items of its previously patient information, such as name. Once this information has been received by receiver 54, microprocessor 630 accesses memory 640 and determines whether that patient can pass through the doorway. If not, microprocessor 630 activates annunciator 95 to warn hospital personnel to prevent the patient from exiting the area. In addition, a record of the patient's movement through the area is also displayed on display and operator controls 698. Furthermore, the patient identification and detection system shown in FIG. 10 can provide multiple levels of surveillance. In particular, identification tag circuitry 700 can also be embedded into an employee badge as well as into an identification tag. In this manner, information can be stored within each badge regarding who that employee is and what areas of the hospital he can access and how many times he can do so during a given interval, e.g. an hour, a day, a week. Microprocessor 630 within processing circuitry 800 can determine the names of those individuals, wearing a badge or wrist band, transitting through a monitored doorway and can keep track of the number of times each such individual has gone through that doorway during a given interval. If unauthorized movement of an individual is detected, annunciator 95 will sound and an appropriate message identifying the specific individual will appear on the display. A number of the systems shown in FIG. 10 can be networked together in a variety of well-known ways, e.g. through serial communication lines inter-connecting the processing circuit of each system with that of another. Each system would moni,tor a different area, e.g. passageway, in the hospital. A separate communeiations and processing circuit would manage the network and display all the information generated by each of the networked monitoring systems to provide overall building surveillance. In addition, the detection circuitry could be encased in a hand held enclosure which allows it to be carried in the field. Hence, the police and other authorities can use the hand held unit to scan a near by area in order to locate an individual who improperly left a facility. Moreover, magnetic strips, other "dumb" tags or "intelligent" tags — all as previously described — could be incorporated into hospital clothing that a patient wears to dispense with the need to place either of these items within the patient identification wrist band. Inasmuch as concealing the tag eliminates the need for any separate identification devices to be worn, an identification tag can be advantageously incorporated into prison clothing as a means of monitoring prisoner movement without their immediate knowledge. Although various embodiments have been shown and described herein, many other varied embodiments incorporating the principles of the present invention can be readily constructed by those skilled in the art,

Claims: We claim: 1. Apparatus for detecting unauthorized movement of an individual through a localized area, said system comprising: means for radiating an interrogating field at a pre-defined frequency within said area, 10 an object to be worn by an individual, magnetic means attached to said object for k generating an harmonic of said frequency whenever said wrist band is placed within said radiated field, and 1 means for detecting said harmonic and for providing an indication thereof. 2. The apparatus in claim 1 wherein said magnetic means comprises an elongated rectangular strip of 0 magnetic materiaL capable of generating an harmonic of said frequency whenever said wrist band is placed within said radiated field. 3. The system in claim 2 wherein the object is a 25 pendant. 4. The system in claim 2 wherein the object is a badge. 30 5. The system in claim 2 wherein the object is a wrist band. 6. The system in claim 5 further comprising: an identification tag having an identification -- strip formed of a slender substantially rectangular strip having two surfaces, wherein information is written on one surface and the magnetic means is affixed to the other surface. 7. The system in claim 6 wherein the magnetic means is laminated between two identification strips with writing surfaces on at least ' one outwardly facing surface of one of said identification strips. 8. A system for detecting unauthorized movement of an individual through a localized area, said system comprising: a transmitter for generating an interrogating field at a first pre-defined carrier frequency and containing an interrogating message; an object to be worn by an individual; an identification tag attached to said object and having a transceiver system responsive to said interrogating field for generating a response message identifying said individual, wherein said transceiver system comprises: a radio transceiver circuit controlled by a processing element for receiving said interrogating field and for extracting said interrogating message and for transmitting said response message at a second pre-defined carrier frequency; a first processing element connected through first interface circuitry to said transceiver and responsive to said received interrogating message for instructing said transceiver to generate said response message; and memory means connected to said first processing element for storing said response message; and means for detecting said response message and for providing an indication thereof; wherein said detection means comprises: a receiver tuned to the second pre-defined carrier frequency for extracting said response message therefrom; a second processing element, connected through second interface circuitry both to said transmitter and said receiver and responsive to said received response message, for instructing said transceiver to generate said interrogating message; and means responsive to said second processor for providing an indication of unauthorized movement through said area. 9. The system in claim 8 wherein said first and second interface circuitry can be connected together to facilitate communication between said first and second processors. 10. The system in claim 9 wherein patient information is stored in said memory and is selectively transmitted by said transceiver as part of said response message. 11. The system in claim 10 wherein said system further comprises means for counting the number of times the individual moves through said area and for providing an indication thereof whenever said count exceeds a pre¬ defined number. 12. The system in claim 11 wherein the object is a pendant. 13. The system in claim 11 wherein the object is a badge. 14. The system in claim 11 wherein the object is a wrist band.

Inventors: HALM EILEEN FRANCIS, HALM JOHN, HALM, EILEEN, FRANCIS, HALM, JOHN
Applicants: PAL ENTERPRISES
Application year: 1986
Main classification: G08B13
IPC codes: A61B5, G06K19, G07C9