Device and process for detecting and identifying wearable user identification units

• US 5,984,175 A
• Filed: 08/28/1997
• Issued: 11/16/1999
• Est. Priority Date: 04/03/1997
• Status: Expired due to Fees

• Current Assignee: Dragerwerk AG & Company KGaA (FPS Vermögensverwaltung GmbH)
• Original Assignee: Dragerwerk AG
• Inventors: Popp, Hans-Joachim
• Primary Examiner(s): Hajec, Donald
• Assistant Examiner(s): SHERR, DANIEL H
• Application Number:
  US08/919,981
• Time in Patent Office: 810 Days
• Field of Search: 235/375, 235/382, 235/492, 340/825.69
• US Class Current: 235/375
• CPC Class Codes: G07C 9/28 the pass enabling tracking or indicating presence

Abstract

A device for detecting and identifying wearable identification units (20) for users at a predetermined distance around a central station (2). The central station (2) has a transmitter (4) and a receiver (6) for electromagnetic signals and a control unit (8), which initiates the sending of a polling signal at predetermined time. The time may be based on multiples of intervals. Furthermore, there are a plurality of wearable identification units (20), which have a transmitter (22) and a receiver (24) for electromagnetic signals and a control unit (26), which is designed to initiate the sending of an identification unit-specific response signal by the transmitter (22) upon the reception of the polling signal after a time delay which is specific of the particular identification unit (20), wherein the identification unit-specific time delays of the plurality of identification units (20) are selected to be such that the response signals of no pair of identification units (20) will overlap when the pair of identification units (20) receives the polling signals of the central station (2). The control unit (8) of the central station (2) is designed to analyze the signal received after the sending of the polling signal and to determine the time between the sending of the polling signal and the reception of a signal in order to detect the presence of an identification unit (20) and to identify it based on the identification unit-specific response signal and based on the identification unit-specific time delay.

Claims

1. A device for detecting system users, comprising:

a central station disposed within a predetermined distance around an area for the system users, said central station having a transmitter and a receiver for electromagnetic signals and with a control unit, said central station control unit initiating the sending of a polling signal by said transmitter at predetermined times; and

a plurality of wearable identification units for the system users, said identification units each having a transmitter and a receiver for electromagnetic signals and an identification unit control unit, said identification unit control unit initiating a sending of an identification unit-specific response signal by said identification unit transmitter upon a reception of the polling signal by said identification unit receiver after a time delay, said time delay being unique to a particular identification unit of said identification units, said identification unit-specific time delays of said plurality of identification units being selected such that response signals of said identification units will not overlap in time when any of said identification units receives a polling signal of said central station, said central station control unit analyzing signals received by said central unit receiver after sending the polling signal and determining a time duration between the sending of the polling signal and the reception of a signal, for detecting the presence of said particular identification unit at a predetermined distance around said central station based on the identification unit-specific response signal and based on the identification unit-specific time delay.

2. The device in accordance with claim 1, wherein said control unit of each said identification units locks said identification unit for the sending of additional response signals for a time period which is longer than the maximum, identification unit-specific time delay in the plurality of said identification units after the sending of the response signal.

3. The device in accordance with claim 1, wherein said central station transmitter and said wearable identification unit transmitter are infrared transmitters and said central station receiver and said wearable identification unit receiver are infrared receivers.

4. The device in accordance with claim 1, wherein each said identification unit control unit generates as the identification unit-specific response signal a set of pulses.

5. The device in accordance with claim 1, further comprising:

control means for activating and deactivating said at least one of a monitoring device and medical device in response to signals from said central station control unit.

6. The device according to claim 1, wherein:

said polling signal is a single signal and all said identification units respond to said single polling signal with respective said response signals after respective said time delays.

7. The device according to claim 1, wherein:

a round trip time of said polling signal to each of said identification units and said response signal to said central station is different for each of said identification units.

8. A system for detecting authorized users, comprising:

a central station disposed within a predetermined distance around an area for the system users, said central station having a transmitter and a receiver for electromagnetic signals and with a control unit, said central station control unit initiating the sending of a polling signal by said transmitter at predetermined times; and

a plurality of wearable identification units for the system users, said identification units each having a transmitter and a receiver for electromagnetic signals and an identification unit control unit, said identification unit control unit initiating a sending of an identification unit-specific response signal by said identification unit transmitter upon a reception of the polling signal by said identification unit receiver after a time delay, said time delay being unique to a particular identification unit of said identification units, said identification unit-specific time delays of said plurality of identification units being selected such that response signals of said identification units will not overlap in time when any of said identification units receives a polling signal of said central station, said central station control unit analyzing signals received by said central unit receiver after sending the polling signal and determining a time duration between the sending of the polling signal and the reception of a signal, for detecting the presence of said particular identification unit at a predetermined distance around said central station based on the identification unit-specific response signal and based on the identification unit-specific time delay.

9. The system in accordance with claim 8, wherein said control unit of each said identification unit locks said identification unit for the sending of additional response signals for a time period which is longer than the maximum, identification unit-specific time delay in the plurality of said identification units after the sending of the response signal.

10. The system in accordance with claim 8, wherein said central station transmitter and said wearable identification unit transmitter are infrared transmitters and said central station receiver and said wearable identification unit receiver are infrared receivers.

11. The system in accordance with claim 8, wherein each said identification unit control unit generates as the identification unit-specific response signal a set of pulses.

12. The system in accordance with claim 8, wherein said central station is associated with at least one of a monitoring device and medical device, supporting vital functions of a patient.

13. The system in accordance with claim 9, further comprising:

control means for activating and deactivating said at least one of a monitoring device and medical device in response to signals from said central station control unit.

14. The system according to claim 8, wherein:

said polling signal is a single signal and all said identification units respond to said single polling signal with respective said response signals after respective said time delays.

15. The system according to claim 8, wherein:

a round trip time of said polling signal to each of said identification units and said response signal to said central station is different for each of said identification units.

16. Process for the wireless detection of the presence of an authorized user of a system, the process comprising the steps of:

providing a central station;

providing authorized system users with a particular identification unit for users at a predetermined area around said central station;

operating an electromagnetic signal transmitter and a receiver with a control unit at the central station such that the transmitter sends a polling signal at predetermined time intervals;

operating an electromagnetic signal transmitter and a receiver at the identification units with a control unit which initiates the sending of an identification unit-specific response signal by the transmitter upon the reception of the polling signal by the said receiver and after a time delay which is unique to each said particular identification unit;

selecting identification unit-specific time delays of the plurality of said identification units to be such that the response signals of no pair of said identification units will overlap in time when such pair of identification units receives the polling signal of the central station; and

analyzing the signals received by the central station receiver with the control unit of the central station after the sending of the polling signal and determining the time between the sending of the polling signal and the reception of a signal in order to detect the presence of said particular identification unit at the predetermined distance around the central station and to identify said particular identification unit based on the identification unit-specific response signal and based on the identification unit-specific time delay.

17. The process in accordance with claim 16, wherein after the sending of the response signal, each said identification unit is prevented from sending additional response signals for a period of time which is longer than the maximum, identification unit-specific time delay of the plurality of said identification units.

18. The process according to claim 16, further comprising:

providing at least one of a monitoring device and medical device, supporting vital functions of a patient, associated with said central station and controlling authorization for changing a setting of the device as a function of the detected presence of said predetermined identification units.

19. The process according to claim 16, wherein:

said polling signal is a single signal and all said identification units respond to said single polling signal with respective said response signals after respective said time delays.

20. The process according to claim 16, wherein:

a round trip time of said polling signal to each of said identification units and said response signal to said central station is different for each of said identification units.