WO2003040896A1

WO2003040896A1 - Personal access control system

Info

Publication number: WO2003040896A1
Application number: PCT/DK2002/000746
Authority: WO
Inventors: Bent Jensen; Tommy L. Jensen; Per Winther
Original assignee: Secure Access Management Aps
Priority date: 2001-11-05
Filing date: 2002-11-05
Publication date: 2003-05-15
Also published as: DK200101641A

Abstract

A display is connected to a computer and will show the data put on the screen by the operator. When the operator for any reason leaves the display, the data will be open to public inspection, thereby making it possible for unauthorized persons to pry into other people's privacy. To this end, the present invention suggests a personal access control system for operators of a display connected to a computer comprising: (1) A control box situated between the computer and the display, where the control box, having at least a receiver, a decoder logic, a memory, and an ON/OFF-logic, frequently receive signals for maintaining the connection between computer and display, these signals being generated by (2) A key or ID module being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the control box, where in the receiver (3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display.

Description

PERSONAL ACCESS CONTROL SYSTEM

BACKGROUND OF THE INVENTION

Field of the Invention This invention relates generally to a personal access control system, particularly a personal access control to areas or sections of buildings with high security level, and more particularly for operators of a display comiected to a computer, e.g. a system preventing non-authorized persons prying into computer displays, which includes a transmitter and a receiver reacting on the transmitted signals originating from the vicinity of the operator, and a threshold detector. In the present description an operator is considered any person authorized to enter a section or area of a building or use a computer and its display, e.g. a doctor, a medical secretary, a social worker, a scientist, or a rector. The meaning of the word "display" is: The visual representation of the output of an electronic device, as the screen of a cathode ray tube or a plasma screen [Webster's Encyclopedic Unabridged Dictionary, Random House, 1996].

Description of the Prior Art

The problem of detecting the presence of persons or articles in allowed areas has been addressed and solved by various systems. U.S. Pat. No. 4,593,273 to Narcisse discloses an out-of-range monitor and alarm system for supervised persons, which includes a base unit transmitting a signal to a mobile unit carried by the person being supervised. The mobile unit responds to a threshold circuit, which is adjustable to a prescribed distance between the base and the supervised person. When the distance is exceeded as indicated by a drop in sig- nal strength, a transmitter in the mobile unit signals to the base to indicate the straying of the supervised person beyond acceptable limits. The mobile unit may also sound an alarm to alert the supervised person that he is straying beyond the prescribed area. U.S. Pat. No. 4,918,425 to Greenberg et al. discloses a monitoring and locating sys- tem for an object attached to a transponder monitored by a base station having an associated ID code where the base indicated by an alarm the absence of a timely appropriate response from the transponder. The base is capable of performing and participating in homing techniques to locate the lost transponder. A list of the IDs of all transponders reported missing is distributed from a central source by nationwide communication to a network of radio stations, each station broadcasting the list in an encoded signal in repetitive sequence along with regular programming. Cruising vehicles of public safety departments operating locally nationwide are equipped with automatic monitors for receiving specially encoded messages including IDs from transponders within their area. Each transponder, after failing to receive a signal from its base for a predetermined time period has the capability of scanning the band of the radio station network, locking onto the local station of the network and receiving its ID from the locked-on station when reported lost. Upon receipt of its ID from the locked-on station, the transponder initiates transmission of the specially coded message to make its presence known to the monitor of a local cruising vehicle and thereafter is capable of establishing communication with a local base for participation in local homing.

SUMMARY OF THE INVENTION

Among the object of the invention is to satisfy the need to prevent non-authorized person's access, particularly to areas or sections of buildings with high security level or e.g. cash registers, and more particularly to prevent non-authorized persons to pry into data on displays that have been left by their operators for a short term, e.g. few minutes. Often, it happens that an operator at a cash register or a display during the servicing of customers or clients will have to leave for a short term, e.g. for photo copying a document or responding to a telephone call. In the absence of the operator, unauthorized persons or clients will have the opportunity of taking money from the cash register or prying into the data still displayed on the screen and possibly call new records concerning other persons up to the screen. This, of course, is not satisfying to neither the operator, who might have cash loss or a professional secrecy obli- gation, nor to the person, whose data are read by unauthorized persons. The principal object of the invention, therefore, is to provide means for controlling the unauthorized personal access to areas or sections of buildings with high security level, a cash register or to a display of a computer during the absence of the operator thereby preventing prying into the data left on the display. Another object of the invention is, when the computer is part of a network, to locate the operator, when sending a message to him and his whereabouts is unknown. Further, another object of the invention is to have the identification of the operator established with passive components not needing a power supply thereby making the identification key simpler and easier to carry around. Still, another object of the invention is to indicate a method for preventing non- authorized persons to pry on data represented on a display, also when the computer is a part of or a hub in a network.

Briefly described, the invention disclosed herein includes a personal control system for operators comprising: (1) A control box situated between the computer and the display, where the control box, having at least a receiver, a decoder logic, a memory, and an

ON/OFF-logic, frequently receive signals for maintaining the connection between computer and display, these signals being generated by

(2) A key or ID module being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the control box, where in the receiver

(3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display.

The object of the subject matter invention is to turn off, automatically, the access to e.g. a display, when the operator leaves the surroundings of the display and to turn on, automatically, the display, when the operator is approaching the display, and to this end the elements of the personal control system comprise a control box situated between the computer and the display, where the control box frequently request signals transmitted by an identification key, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal to- gether with the operator's ID code to the control box, where a threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display.

During the cut-off phase, the display can be either switched off or it can switch to a mode, where a screen saver takes over the control of the display. In both cases, the unauthorized person will have no access neither to the data represented on the screen nor to any other data present in the computer. This is of great importance, as data represented on a screen often are sensible, e.g. when a doctor has patient data or an auditor has taxation data on the screen. Thereby, the operator of the display, e.g. a doctor, can leave the workstation for short periods without having sensible data laid open to public inspection. With the personal control system it will be possible to have more than one operator to a given display, so different operators can have access to the display, as long as they carry a recognized identification key, thereby easing the use of the computer and display. This is an advantage when e.g. several operators have access to a cash register or when servants in a restaurant address the cash register for orders. When the computer is part of or a hub in a network, it will also be possible to locate any operator, when his whereabouts is unknown. To this end, the invention further suggests a connection from the control box to the computer making it possible to transmit the operator's identity to the computer or the computer network. Thereby, it will be possible to address the display closest to the addressed operator and possibly to have the operator respond using the closest display and keyboard. Further, an op- erator can avoid entering user-ids and passwords, as the operator's ID is already known to the computer. When many operators have access to a computer system, it might be more cost reducing to have the identification of the operator established with passive components not needing a power supply, thereby making the identification key simpler, more cost reductive, and easier to carry around. Such identification key is often made as a transponder. This is an advance, as it is often seen, that if a gadget is too heavy, the carrier has a tendency to lay down the heavy gadget on a table and forget all about it. This causes great confusion and some operators might even unintentionally swap identification keys. With identification keys according to this embodiment, the carrying of the key will cause no extra burden on the operator. When all the operators are carrying their personal transponders, it will, also, be easier to locate an operator, when his whereabouts is unknown.

The invention disclosed herein also includes a method for a control system for operators of a display connected to a computer using:

(1) A control box situated between the computer and the display, where the control box, having at least a receiver, a decoder logic, a memory, and an ON/OFF-logic, frequently receive signals for maintaining the connection between computer and display, these signals being generated by

(3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display. The object of the method is to turn off, automatically, the display, when the operator leaves the surroundings of the display and to turn on, automatically, the display, when he is approaching the display, and to this end the method suggest the use of a control box situated between the computer and the display, where the control box frequently request signals transmitted by an identification key, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the control box, where a threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his sig- nals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display.

During the cut-off phase, the method suggests either to switch off the display or to switch to a mode, where a screen saver takes over the control of the display. In both cases, the unauthorized person will have no access neither to the data represented on the screen nor to any other data present in the computer.

With the method it will be possible to have more than one operator to a given display, so different operators can have access to the display, as long as they carry a recognized identification key, thereby easing the use of the computer and display. When the computer is part of or a hub in a network, the method also suggests locat- ing any operator, when his whereabouts is unknown. Thereby, it will be possible to address the display closest to the addressed operator and possibly to have the operator respond using the closest display and keyboard.

A further embodiment of the method also suggests the use of an identification key made as a transponder. This is, as mentioned above, an advantage, as it is often seen, that if a gadget is too heavy, the carrier has a tendency to lay down the heavy gadget on a table and forget all about it. This causes great confusion and some operators might even unintentionally swap identification keys. With the use of an identification key according to this embodiment of the method, the carrying of the key will cause no extra burden on the operator. When all the operators are carrying their personal transponders, it will, also, be easier to locate an operator, when his whereabouts is unknown. It is to be understood that the present improvements are applicable to a range of computers and displays, including those with display built into the computer housing.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a flow chart representing a typical chain of decisions and actions performed by the control box according to the present invention.

Fig. 2 shows a flow chart for the control box in the learning mode, where a new ID is introduced to the control box.

Fig. 3 shows a block diagram representing an identification key and, in dotted lines, the possibility of transforming it to a transponder.

Fig. 4 shows a block diagram representing a control box with the elements necessary for identifying the keys and, in dotted lines, the possibility of transmitting signals to a transponder.

Fig. 5 shows the arrangement of the control box between the computer and the display. Fig. 6 shows an example of an operator carrying the identification key or the transponder, respectively.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Fig. 1 shows a flow chart representing a typical chain of decisions and actions per- formed by the control box during start up and operation of the computer with the display. After initiation, where the control box checks whether or not a new operator shall be introduced to the system and allows the operator to find his identification key etc. the control box looks for any input from the identification key being sufficiently large to be entered. After having received the ID it is checked whether or not the ID is valid. If the input is not sufficiently large to be entered or the ID is not valid, the display will be turned off, and the control box will again look for input. When the ID is valid, the display will either be turned on or stay turned on for a while exceeding the period between the transmissions of the identification key, where the duration of the period could be, as an example, 10 seconds, depending on the acceptable duration from an operator leaves the display until the display is turned off. If the operator is still close to the display, the display will stay turned on. Fig. 2 shows a flow chart for the control box in the learning mode, where a new operator's ID is introduced to the control box after the learn key has been activated. Here the ID is entered by any means appropriate and the reception is checked.

As a security measure only known IDs will be allowed, so to this end also the ID is compared to stored IDs, and if unknown, the ID will be erased. If, however, the ID is known, the ID is added to the list of active IDs, and a visible signal of acceptance will be given to the operator, after which the learning mode will be left, and the con- trol box will start looking for input as mentioned above.

Fig. 3 is a block diagram representing an identification key 1. The basic elements of the identification key 1 in relation to the present invention are the code generation logic 2, which frequently produces a signal mixed with the identification code for the operator assigned to the identification key. The signal is lead to a transmitter 3 sending the signal by any means appropriate to the purpose. The transmission can take place by means of radio, acoustics, Infra Red or visible light and the transmission as such is not important as long as the range of the transmitted signals is limited, e.g. to below 100 meters (300 feet).

Fig. 4 is a block diagram representing a control box 4 with the elements necessary for identifying the identification keys. The basic elements important to the present invention are the receiver 5 being able to receive the signals transmitted from the identification key 1 and comparing the amplitude of the received signal with a predetermined value for setting the range of the operator's distance from the display. Having been accepted by the receiver 5 the signal is lead to the decoder logic 6, which reads the ID and checks with the accepted values of operators, which values are stored in the memory 8. Depending on the ID check a signal is lead to the ON/OFF logic 7, which drives the unit 9 turning ON or OFF the display. The functions of the elements shown in figs. 3 and 4 can be realized either in a hardware configuration or in a software configuration. In the software configuration the

5 control box can be realized as a program sequence being run in the computer, thereby enabling the computer to control the display depending on the presence of an operator with the identification key attached to him.

Fig. 5 shows the arrangement of the control box 4 between the computer and the display. It should be noted, that the signals between the CPU and display can be ei- o ther be through wiring, but also by means of radio, acoustics, Infra Red or visible light but the communication between CPU and display as such is not important. The important measure is that the control box 4 is arranged between the CPU and the display thereby being able to control the display in dependency of the presence of an operator as disclosed in the present invention. s Fig. 6 shows an example of an operator carrying the identification key 1 or the transponder 1, respectively. This is just an example and as outlined in the claims, there are many possible ways of arranging the identification key 1 or the transponder 1 respectively. In a further embodiment of the invention it is suggested having a transmitter 10 in o the control box 4, thereby letting the control box 4 contain the power supply to the transmitter. This, of course, will have the effect, that the identification key 1 should not carry any power supply and will therefore be easier to carry around to the operator. In addition, the identification key 1 should be transformed to a transponder carrying a receiver 11, which can activate the code generation logic 2. In this way, the 5 identification key will now work as a transponder with the same control results for the display.

Parts or elements for the electric or electronic circuits described in the present invention also contain standard elements such a switches, power supplies, integrated circuits, optical communication elements, operational amplifiers, antennas, housings, o etc. all being evident to persons skilled in the art. Even if such standard elements are not mentioned, they are just presumed present, particularly if they have no contribution to the invention and therefore are not mentioned.

This disclosure is illustrative and not limiting; further modifications will be apparent in light of this disclosure and are intended to fall within the scope of the appended claims. Also, it is to be understood that the various features described herein may in at least some cases be independent of one another, and it is contemplated that a computing device or its display may include only some of these features.

Claims

PATENT CLAIMS

1. Personal access control system for operators of a display connected to a computer comprising:

(1) A control box situated between the computer and the display, where the control box, having at least a receiver, a decoder logic, a memory, and an

2. Control system according to claim 1, where the control box is arranged in the wiring between computer and display.

3. Confrol system according to claim 2, where range of the transmitter is limited to below 10 meters [30 feet].

4. Confrol system according to claim 3, where range of the transmitter is limited to below 3 meters [10 feet].

5. Confrol system according to claim 3, where the transponder is placed in the garment of the operator.

6. Control system according to claim 5, where the transponder is placed in the spectacles of the operator.

7. Control system according to claim 5, where the transponder is placed in the jewelry of the operator.

8. Personal access control system for operators of a display connected to a computer being installed in a network comprising:

(1) A confrol box situated between the computer and the display, where the control box, having at least a receiver, a decoder logic, a memory, and an

5 ON/OFF-logic, frequently receive signals for maintaining the connection between computer and display, these signals being generated by

(2) A key or ID module being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the. control box, where in the re- o ceiver

(3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized s operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display, and

(4) A connection from the control box to the computer making it possible to transmit the operator's identity to the computer or the computer network.

9. Confrol system according to claim 8, where the control box is arranged in the o wiring between computer and display.

10. Confrol system according to claim 9, where range of the transmitter is limited to below 10 meters [30 feet].

11. Control system according to claim 10, where range of the transmitter is limited to below 3 meters [10 feet]. 5

12. Control system according to claim 10, where the fransponder is placed in the garment of the operator.

13. Confrol system according to claim 12, where the fransponder is placed in the spectacles of the operator.

14. Control system according to claim 12, where the transponder is placed in the o jewelry of the operator.

15. Personal access confrol system for operators of a display connected to a computer comprising:

(1) A control box situated between the computer and the display, where the control box frequently emits request signals to be responded by,

5 (2) A fransponder, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a response to the request signal from and emit the response together with the operator's ID code to the control box, where in the receiver

(3) A threshold circuit supervising the amplitude of the signal comparing the ιo amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his transponder signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the dis- i5 play.

16. Control system according to claim 15, where the control box is arranged in the wiring between computer and display.

17. Control system according to claim 16, where range of the fransmitter is limited to below 10 meters [30 feet].

20 18. Control system according to claim 17, where range of the transmitter is limited to below 3 meters [10 feet].

19. Control system according to claim 17, where the transponder is placed in the garment of the operator.

20. Confrol system according to claim 19, where the transponder is placed in the 25 spectacles of the operator.

21. Control system according to claim 19, where the fransponder is placed in the jewelry of the operator.

22. Personal access control system for operators of a display connected to a computer being installed in a network comprising:

30 (1) A control box situated between the computer and the display, where the control box frequently emits request signals to be responded by, (2) A fransponder, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a response to the request signal from and emit the response together with the operator's ID code to the confrol box, where in the receiver (3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his transponder signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display, and

23. Control system according to claim 22, where the control box is arranged in the wiring between computer and display.

24. Control system according to claim 23, where range of the transmitter is limited to below 10 meters [30 feet].

25. Control system according to claim 24, where range of the transmitter is limited to below 3 meters [10 feet].

26. Confrol system according to claim 24, where the transponder is placed in the garment of the operator.

27. Confrol system according to claim 26, where the transponder is placed in the spectacles of the operator.

28. Confrol system according to claim 26, where the transponder is placed in the jewelry of the operator.

29. Method for verifying the presence of an operator using a personal access confrol system according to claim 1 comprising the use of

(1) A confrol box situated between the computer and the display, where the confrol box, having at least a receiver, a decoder logic, a memory, and an ON/OFF-logic, frequently receive signals for maintaining the connection between computer and display, these signals being generated by (2) A key or ID module being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the control box, where in the receiver (3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the ON/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold cir- cuit reactivates the ON/OFF-logic circuit for the display.

30. Method for verifying the presence of an operator according to claim 29, where the control box is arranged in the wiring between computer and display.

31. Method for verifying the presence of an operator according to claim 30, where range of the fransmitter is limited to below 10 meters [30 feet].

32. Method for verifying the presence of an operator according to claim 31 , where range of the transmitter is limited to below 3 meters [10 feet].

33. Method for verifying the presence of an operator according to claim 31, where the transponder is placed in the garment of the operator.

34. Method for verifying the presence of an operator according to claim 33, where the transponder is placed in the spectacles of the operator.

35. Method for verifying the presence of an operator according to claim 33, where the transponder is placed in the jewelry of the operator.

36. Method for verifying the presence of an operator using a personal access control system according to claim 8 comprising the use of (1) A control box situated between the computer and the display, where the confrol box, having at least a receiver, a decoder logic, a memory, and an

(2) A key or ID module being placed on or in the vicinity of an operator, having a circuitry being able to prepare a signal and transmit the signal together with the operator's ID code to the control box, where in the receiver (3) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the ON/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/OFF-logic circuit for the display.

37. Method for verifying the presence of an operator according to claim 29, where the control box is arranged in the wiring between computer and display.

38. Method for verifying the presence of an operator according to claim 30, where range of the transmitter is limited to below 10 meters [30 feet].

39. Method for verifying the presence of an operator according to claim 31, where range of the fransmitter is limited to below 3 meters [10 feet].

40. Method for verifying the presence of an operator according to claim 31, where the transponder is placed in the garment of the operator.

41. Method for verifying the presence of an operator according to claim 33, where the transponder is placed in the spectacles of the operator.

42. Method for verifying the presence of an operator according to claim 33, where the fransponder is placed in the j ewelry of the operator.

43. Method for verifying the presence of an operator using a personal access confrol system according to claim 15 comprising the use of

(1) A control box situated between the computer and the display, where the control box frequently emits transmitted request signals to be responded by,

(2) A transponder, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a response to the request signal from and emit the response together with the operator's ID code to the confrol box, where in the receiver (3) A threshold circuit supervises the amplitude and/or phase of the response comparing the response to a predetermined value and triggering a cut off circuitry for the display, until the operator or another authorized operator approaches the display with his transponder signals, where the threshold circuit inactivates the cut off circuit for the display.

44. Method for verifying the presence of an operator according to claim 43, where 5 the confrol box is arranged in the wiring between computer and display.

45. Confrol system according to claim 44, where range of the fransmitter is limited to below 10 meters [30 feet].

46. Control system according to claim 45, where range of the fransmitter is limited to below 3 meters [10 feet]. o

47. Control system according to claim 45, where the transponder is placed in the garment of the operator.

48. Control system according to claim 47, where the transponder is placed in the spectacles of the operator.

49. Confrol system according to claim 47, where the transponder is placed in the s j ewelry of the operator.

50. Method for verifying the location of an operator using a personal access control system according to claim 22 comprising the use of:

(1) A control box situated between the computer and the display, where the control box frequently emits request signals to be responded by, 0 (2) A fransponder, being placed on or in the vicinity of an operator, having a circuitry being able to prepare a response to the request signal from and emit the response together with the operator's ID code to the confrol box, where in the receiver

(3) A threshold circuit supervising the amplitude of the signal comparing the 5 amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his transponder signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the dis- o play, and (4) A connection from the confrol box to the computer making it possible to transmit the operator's identity to the computer or the computer network.

51. Method for verifying the location of an operator according to claim 50, where the control box is arranged in the wiring between computer and display.

52. Method for verifying the location of an operator according to claim 51, where range of the transmitter is limited to below 10 meters [30 feet].

53. Method for verifying the location of an operator according to claim 52, where range of the transmitter is limited to below 3 meters [10 feet].

54. Method for verifying the location of an operator according to claim 52, where the transponder is placed in the garment of the operator.

55. Method for verifying the location of an operator according to claim 54, where the fransponder is placed in the spectacles of the operator.

56. Method for verifying the location of an operator according to claim 54, where the transponder is placed in the jewelry of the operator.

57. Device for being placed on or in the vicinity of an operator in a personal access control system according to claim 1 comprising a code generation logic, the output from which is lead to a transmitter having a limited range.

58. Device according to claim 57, where the range is limited to 10 m [30 feet].

59. Device according to claim 58, where the range is limited to 3 m [10 feet].

60. Device according to claim 58, where it is placed in the garment of the operator.

61. Device according to claim 60, where it is placed in the spectacles of the operator.

62. Device according to claim 60, where it is placed in the jewelry of the operator.

63. Transponder for being placed on or in the vicinity of an operator in a personal access confrol system according to claim 15 comprising a receiver for the signals from the confrol box, the signals being lead to a code generation logic, the output from which is lead to a fransmitter having a limited range.

64. Transponder according to claim 63, the range of which is limited to 10 m [30 feet].

65. Transponder according to claim 64, the range of which is limited to 3 m [10 feet].

66. Transponder according to claim 64, where it is placed in the garment of the operator.

67. Transponder according to claim 66, where it is placed in the spectacles of the operator.

68. Transponder according to claim 66, where it is placed in the jewelry of the operator.

69. Confrol box according to claim 1 , comprising

(1) a receiver, a decoder logic, a memory, and an ON/OFF-logic, having in the receiver (2) A threshold circuit supervising the amplitude of the signal comparing the amplitude of the signal to a predetermined minimum value and triggering the (ON)/OFF-logic circuitry for the display, if the signal amplitude is below the predetermined value, until the operator or another authorized operator approaches the display with his signals, whereby the threshold circuit reactivates the ON/(OFF)-logic circuit for the display.

70. Control box according to claim 69, further comprising a fransmitter for frequently emitting request signals, which are being echoed by a fransponder together with the identification of the operator, assigned to the fransponder.