Detector and Optical System

• US 20080272281A1
• Filed: 02/01/2006
• Published: 11/06/2008
• Est. Priority Date: 03/10/2005
• Status: Active Grant

• Current Assignee: Pyronix Ltd. (Hangzhou Hikvision Digital Technology Company Limited)
• Original Assignee: Pyronix Ltd. (Hangzhou Hikvision Digital Technology Company Limited)
• Inventors: Stromberg, Juan Sebastian H., Leivers, Craig
• Granted Patent: US 8,044,336 B2
• Time in Patent Office: Days
• US Class Current: 250/216
• CPC Class Codes: G08B 13/189 using passive radiation detection systems
• CPC Class Codes: G08B 13/193 using focusing means
• CPC Class Codes: G08B 29/046 prevention of tampering with detection circuits
• CPC Class Codes: G08B 29/183 Single detectors using dual technologies G08B13/1672, G08B13/2448, G08B13/2494 take precedence

Abstract

Embodiments of the present invention relate to a detector comprising first and second lenses for use with respective first and second sensing means; each lens comprising a plurality of Fresnel facets having respective fields of view adapted such that the fields of view of the first lens are alternately arranged with the fields of view of the second lens such that the fields of view of the first lens are adjacent only to, but do not over-lap with, the fields of view of the second lens in a single direction.

Claims

1. A detector comprising first and second lenses for use with respective first and second sensing means;

each lens comprising a plurality of Fresnel facets having respective fields of view adapted such that the fields of view of the first lens are alternately arranged with the fields of view of the second lens such that the fields of view of the first lens are adjacent to, but do not overlap with, the fields of view of the second lens in a single direction.

2. A detector as claimed in claim 1 in which the fields of view of at least one of the first and second lenses are arranged as a number of sets of fields of view.

3. A detector as claimed in claim 2 in which the fields of view of a first set are linearly arranged.

4. A detector as claimed in claim 2 or 3 in which the fields of view of a second set are linearly arranged.

5. A detector as claimed in any of the preceding claims in which the fields of view of the first lens have a common first focus.

6. A detector as claimed in any preceding claim in which the fields of view of the second lens have a common second focus.

7. A detector as claimed in any of claims 1 to 4 in which the fields of view of the first lens have a first common focus, the fields of view of the second lens have a second common focus and the first and second common focuses are vertically disposed relative to one another.

8. A detector as claimed in any of the preceding claims in which the at least one field of view is, and preferably all of the fields of view are, divergent.

9. A detector as claimed in claim 8 in which all of the fields of view are divergent.

10. A detector as claimed in any of the preceding claims, wherein the first sensing means comprises at least one of a PIR detector, AIR detector, microwave detector and ultrasonic sensor.

11. A detector as claimed in any of the preceding claims, wherein the second sensing means comprises at least one of a PIR detector, AIR detector, microwave detector and ultrasonic sensor.

12. A detector as claimed in any of the preceding claims, further comprising a monitoring system responsive to an output signal of at least one of the sensing means for providing an indication of tampering with the detector, or masking at least one of the sensing means, wherein the monitoring system is responsive to an output signal from at least one of the first and second sensing means indicating the detection of an event proximate to the detector.

13. A detector as claimed in any of claims 1 to 11, further comprising a monitoring system which comprises:

comparator means for comparing a first output signal of one of the first and second sensing means with a threshold signal and for activating a timer when the first output signal exceeds a threshold on a first occasion,

masking indicating means adapted to provide a masking indicating output after a predetermined time interval unless at least one of the first and second sensing means generates an output signal in response to the detection of an event on a second occasion within the predetermined time interval.

14. A detector as claimed in any of claims 1 to 11, further comprising third sensing means and a monitoring system which comprises:

comparator means for comparing a first output signal of one of the first and second sensing means with a threshold signal and for activating a timer when the first output signal exceeds the threshold signal on a first occasion; and

masking indicating means adapted to provide a masking indicating output after a predetermined time interval unless at least one of the first and second sensing means generates an output signal in response to the detection of an event, and the third sensing means generates an output signal in response to the detection of an event, within the predetermined time interval.

15. A detector as claimed in claim 14, wherein the third sensing means comprises at least one of a PIR detector, AIR detector, microwave detector and ultrasonic sensor.

16. A detector as claimed in any of claims 13 to 14, wherein when the timer is activated, if an output signal indicating a distant event is received from at least one of the sensing means the timer is re-set, and if an output signal indicating a proximate event is received from at least one of the sensing means the timer is re-set and re-started, and if no output signal is received the masking indicating output is activated.

17. A detector as claimed in any of claims 13 to 16, wherein the predetermined time interval is from 5 seconds to 5 minutes.

18. A detector as claimed in any of claims 1 to 11, further comprising a monitoring system comprising:

a timer which is started in response to a first signal from at least one of the first and second sensing means indicating detection of an event proximate to the detector, restarted in response to subsequent detection of the first signal from at least one of the first and second sensing means, and reset in response to detection of a second signal from at least one of the first and second sensing means indicating detection of an event distant from the detector; and

masking indicating means adapted to provide a masking indicating output if the timer reaches a predetermined time without being restarted.

19. A detector as claimed in claim 18 wherein the first signal is produced in response to a proximate event within 50 cm of the detector.

20. A detector as claimed in claim 18 or 19, wherein the second signal is produced in response to a distant event more than 50 cm from the detector.

21. A detector as claimed in any of the preceding claims, further comprising a reduction range or blocking detection apparatus comprising means, responsive to at least a first input signal from at least one of the sensing means, to generate a blocking detection signal after a first period of time unless a second input signal is received within the first period of time from at least one of the sensing means.

22. A detector as claimed in claim 21 wherein the means to generate the blocking detection signal comprises a timer arranged to time out after the first period of time and to generate, or cause to be generated, the blocking detection signal and means to detect input of the second input to at least stop or reset the timer.

23. A detector as claimed in claim 21 or 22 wherein the first signal has a first type.

24. A detector as claimed in claim 23 wherein the second signal has a second type.

25. A detector as claimed in claim 24 wherein the first type and the second type are the same.

26. A detector as claimed in claim 24 wherein the first and second signals have different types.

27. A detector as claimed in any of claims 21 to 26, wherein the first signal is derived from a microwave sensor or a PIR sensor.

28. A detector as claimed in any of claims 21 to 27, wherein the second signal is derived from a microwave sensor or a PIR sensor.

32. An optical arrangement or system for a detector as claimed in any of claims 1 to 29.

40. A detector as claimed in any of claims 1 to 29, further comprising means to implement the method as claimed in any of claims 33 to 38.

29. A detector substantially as described herein with reference to and/or as illustrated in the accompanying drawings.

30. An optical arrangement comprising a plurality of Fresnel lenses or Fresnel facets forming first and second sets of fields of view, wherein the first set of fields of view comprises a plurality of non-adjacent fields of view.

31. An optical arrangement as claimed in claim 30 in which the plurality of lenses or facets have disposed there between a plurality of blanks to optically separate the first and second sets of fields of view.

33. A method of detecting masking of sensing means of a detector, comprising

detecting an event proximate the detector using the sensing means;

providing a masking indicating output after a predetermined time period, unless within the predetermined time period the sensing means detects an event.

34. A method as claimed in claim 33, comprising timing the predetermined time period using a timer.

35. A method as claimed in claim 34, comprising restarting the timer if the sensing means detects a further event within the predetermined time period.

36. A method as claimed in claim 35, wherein the further event is a proximate event within 50 cm of the detector.

37. A method as claimed in any of claims 34 to 36, comprising resetting the timer if the sensing means detects a distant event within the predetermined time period.

39. A system comprising means to carry out a method as claimed in any of claims 35 to 40.

41. A computer program comprising code for implementing a method or system as claimed in any of claims 33 to 39.

42. Computer readable storage storing a computer program as claimed in claim 41.

38. A method substantially as described herein with reference to and/or as illustrated in the accompanying drawings.

43. An optical arrangement or lens substantially as described herein with reference to and/or as illustrated in the accompanying drawings.