Microwave sensor and mutual interference preventing system between microwave sensors

• US 7,256,376 B2
• Filed: 03/30/2005
• Issued: 08/14/2007
• Est. Priority Date: 03/30/2004
• Status: Expired due to Fees

• Current Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Original Assignee: Optex Company Limited (OPTEX GROUP Co., Ltd.)
• Inventors: Tsuji, Masatoshi
• Primary Examiner(s): ROBINSON, DANIEL LEON
• Application Number:
  US11/092,713
• Publication Number:
  US 20050236404A1
• Time in Patent Office: 867 Days
• Field of Search: 340/567, 340/566, 340/565
• US Class Current: 219/679
• CPC Class Codes: G01N 22/00 Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more G01N3/00 - G01N17/00, G01N24/00 take precedence
• CPC Class Codes: G01S 15/04 Systems determining presence of a target

Abstract

A microwave sensor is provided that transmits microwaves toward a detection area, performs an object detecting operation based on reflected waves from an object being present in the detection area, and outputs an object detection signal based on a result of the abject detecting operation, the microwave sensor being provided with a detecting operation controller for controlling the object detecting operation to be performed intermittently at a predetermined detection cycle, a time setting changer for changing time setting of the detection cycle, and a filter for preventing a signal outside of a frequency region of a signal obtained when detecting a human figure from being included in the object detection signal and from being output,

Claims

1. A microwave sensor for transmitting microwaves toward a detection area, performing an object detecting operation based on reflected waves from an object being present in the detection area, and outputting an object detection signal based on a result of the object detecting operation, the microwave sensor comprising:

a detecting operation controller for controlling the object detecting operation to be performed intermittently at a predetermined detection cycle,

a time setting changer for changing a time setting of the detection cycle, and

an electrical filter for preventing an electrical signal outside of a frequency region of an electrical signal obtained when detecting a human figure from being output in the object detection signal.

2. The microwave sensor according to claim 1, further comprising:

an information input device for inputting information relating to the time setting of the detection cycle,

wherein the time setting changer changes time setting of the detection cycle based on information input by the information input device.

3. The microwave sensor according to claim 2,

wherein the information input device is at least one DIP switch.

4. The microwave sensor according to claim 2,

wherein the information input device is at least one jumper switch.

5. The microwave sensor according to claim 1, further comprising:

a passive infrared sensor for receiving an infrared ray from the detection area, and for detecting an intruding object based on a temperature difference from its surroundings,

wherein the object detection signal is allowed to be output only when the passive infrared sensor detects an intruding object.

6. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 1, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

7. The mutual interference preventing system according to claim 6, wherein

when a lower limit of a frequency of an acceptable noise that is determined based on an upper limit of a frequency region of a signal obtained when detecting a human figure and characteristics of the filter is taken as fLow,

when a longest one of the detection cycles of the microwave sensors is taken as Tmax, and

when a difference in detection cycle between any two microwave sensors combines is taken as Δ

T,

Δ

T≧

fLow×

Tmax²² is satisfied.

8. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 5, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

9. The mutual interference preventing system according to claim 8, wherein

when a lower limit of a frequency of an acceptable noise that is determined based on an upper limit of a frequency region of a signal obtained when detecting a human figure and characteristics of the filter is taken as fLow,

when a longest one of the detection cycles of the microwave sensors is taken as Tmax, and

when a difference in detection cycle between any two microwave sensors combined is taken as Δ

T,

Δ

T≧

fLow×

Tmax² is satisfied.

10. The microwave sensor according to claim 2, further comprising:

a passive infrared sensor for receiving an infrared ray from the detection area, and for detecting an intruding object based on a temperature difference from its surroundings,

wherein the object detection signal is allowed to be output only when the passive infrared sensor detects an intruding object.

11. The microwave sensor according to claim 3, further comprising:

a passive infrared sensor for receiving an infrared ray from the detection area, and for detecting an intruding object based on a temperature difference from its surroundings,

wherein the abject detection signal is allowed to be output only when the passive infrared sensor detects an intruding object.

12. The microwave sensor according to claim 4, further comprising:

a passive infrared sensor for receiving an infrared ray from the detection area, and for detecting an intruding object based on a temperature difference from its surroundings,

wherein the object detection signal is allowed to be output only when the passive infrared sensor detects an intruding object.

13. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 2, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

14. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 3, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

15. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 4, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

16. The mutual interference preventing system according to claim 13, wherein

when a lower limit of frequency of an acceptable noise that is determined based on an upper limit of a frequency region of a signal obtained when detecting a human figure and characteristics of the filter is taken as fLow,

when a longest one of the detection cycles of the microwave sensors is taken as Tmax, and

when the difference in detection cycle between any two microwave sensors combined is taken as Δ

T,

Δ

T≧

fLow×

Tmax² is satisfied.

17. The mutual interference preventing system according to claim 14, wherein

when a lower limit of frequency of an acceptable noise that is determined based on an upper limit of a frequency region of a signal obtained when detecting a human figure and characteristics of the filter is taken as fLow,

when a longest one of the detection cycles of the microwave sensors is taken as Tmax, and

when the difference in detection cycle between any two microwave sensors combined is taken as Δ

T,

Δ

T≧

fLow×

Tmax² is satisfied.

18. The mutual interference preventing system according to claim 15, wherein

when a lower limit of frequency of an acceptable noise that is determined based on an upper limit of a frequency region of a signal obtained when detecting a human figure and characteristics of the filter is taken as fLow,

when a longest one of the detection cycles of the microwave sensors is taken as Tmax, and

when the difference in detection cycle between any two microwave sensors combined is taken as Δ

T,

Δ

T≧

fLow×

Tmax² is satisfied.

19. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 10, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.

20. A mutual interference preventing system for preventing mutual interference between a plurality of microwave sensors that are used close to each other,

wherein each of the plurality of microwave sensors is a microwave sensor according to claim 11, and

wherein the detection cycles are differentiated from each other by at least a predetermined value by the time setting changers of the microwave sensors.