Detecting system and detector

• US 4,785,283 A
• Filed: 03/13/1987
• Issued: 11/15/1988
• Est. Priority Date: 03/18/1986
• Status: Expired due to Term

• Current Assignee: Hochiki Kabushiki Kaisha
• Original Assignee: Hochiki Kabushiki Kaisha
• Inventors: Yuchi, Sadataka
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/025,503
• Time in Patent Office: 613 Days
• Field of Search: 340/501, 340/500, 340/506, 340/511, 340/510, 340/588, 340/589, 340/521, 340/632, 340/634, 340/630
• US Class Current: 340/501
• CPC Class Codes: G08B 17/00 Fire alarms; Alarms responsive to explosion
• CPC Class Codes: G08B 17/10 Actuation by presence of smoke or gases , e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
• CPC Class Codes: G08B 17/107 for detecting light-scattering due to smoke
• CPC Class Codes: G08B 23/00 Alarms responsive to unspecified undesired or abnormal conditions
• CPC Class Codes: G08B 26/00 Alarm systems in which substations are interrogated in succession by a central station

Abstract

A detecting system and a detector which includes an analog sensor for sensing a change in a quantity of an environmental phenomenon, processes a signal corresponding to a detection level output from said analog sensor to detect a change in the environmental phenomenon, in which the detecting sensitivity of analog sensor may be changed between a plurality of sensitivity levels according to the quantity of the phenomenon.

Claims

1. A detecting system for detecting a change in an environmental phenomenon comprising:

an analog sensor in a detector for sensing said change in a quantity of said environmental phenomenon and having an output signal;

said analog sensor having a detection range classified into a plurality of areas correlating with the quantity of said phenomenon;

a receiver for receiving and processing a signal corresponding to a detection level of an output from said analog sensor;

sensitivity setting means changing automatically a detection sensitivity of said analog sensor when said detection level changes and belongs into another area;

said sensitivity setting means comprising;

level discriminating means for emitting a discrimination signal indicating which one of areas the output signal from said analog sensor is included in;

setting signal emitting means for emitting a sensitivity characteristic level setting signal according to said discrimination signal;

correcting means which can hold the output signal level being emitted from said analog sensor so as not to change when the sensitivity characteristics of said analog sensor is changed and so as to prevent the corresponding relationship between the output signal level from the analog sensor and the quantity of the phenomenon from being discontinuous; and

drive means for driving a sensing element in said analog sensor to vary according to said setting signal;

whereby, said sensitivity of said analog sensor is moved up to a higher level than a current level so as to accomplish a more detailed and precise detection in an area wherein the detection is required, sensitivity of said analog sensor being lowered in the other area wherein a more rough detection than the current level is required.

2. A detecting system as defined in claim 1, wherein said level discriminating means, said setting signal emitting means and said correcting means are located in the receiver, said drive means being located in said analog sensor.

3. A detecting system as defined in claim 2, including an amplifier for amplifying a sensing output signal from said sensing element of the analog sensor, said correcting means varying a threshold level of the amplifier.

4. A detecting system as defined in claim 3, wherein said correcting means stores and holds said sensitivity level setting signal in a readable form, said analog sensor changing the characteristics of a device driving said sensing element by the sensitivity level setting signal to vary the detecting sensitivity level of the analog sensor.

5. A detecting system as defined in claim 1, wherein said level discriminating means and said setting signal emitting means are located in said receiver, said correcting means and said drive means being located in said analog sensor.

6. A detecting system as defined in claim 5, including an amplifier for amplifying a sensing output signal from said sensing element of said analog sensor, said correcting means varying a threshold level of the amplifier.

7. A detecting system as defined in claim 6, wherein said correcting means stores and holds said sensitivity level setting signal in a readable form, said analog sensor changing the characteristics of a device driving said sensing element by the sensitivity level setting signal to vary the detecting sensitivity level of the analog sensor.

8. A detecting system as defined in claim 1, wherein said level discriminating means, said setting signal emitting means, said correcting means and said drive means are located in said analog sensor.

9. A detecting system as defined in claim 8, including an amplifier for amplifying a sensing output signal from said sensing element of the analog sensor, said correcting means varying a threshold level of the amplifier.

10. A detecting system as defined in claim 9, wherein said correcting means stores and holds said sensitivity level setting signal in a readable form, said analog sensor changing the characteristics of a device driving said sensing element by the sensitivity level setting signal to vary the detecting sensitivity level of the analog sensor.

11. A detecting system as defined in claim 1, wherein said level discriminating means, said setting signal emitting means and said drive means are located in said analog sensor, said correcting means being located in said receiver.

12. A detecting system as defined in claim 11, including an amplifier for amplifying a sensing output signal from said sensing element of the analog sensor, said correcting means varying a threshold level of the amplifier.

13. A detecting system as defined in claim 12, wherein said correcting means stores and holds said sensitivity level setting signal in a readable form, said analog sensor changing the characteristics of a device driving said sensing element by the sensitivity level setting signal to vary the detecting sensitivity level of the analog sensor.

14. A detector for detecting a change in an environmental phenomenon comprising:

an analog sensor for sensing a change in a quantity of said environmental phenomenon and having an output signal;

said analog sensor having a detection range classified into a plurality of areas correlating with the quantity of said phenomenon;

sensitivity setting means changing a detection sensitivity of said analog sensor according to said correlation between each of said areas and the quantity of said phenomenon;

said sensitivity setting means comprising;

level discriminating means for emitting a discrimination signal indicating which one of areas the output signal from said analog sensor is included in;

setting signal emitting means for emitting a sensitivity characteristic level setting signal according to said discrimination signal;

correcting means which can hold the output signal level being emitted from said sensor so as not to change when the sensitivity characteristics of said analog sensor is changed and so as to prevent the corresponding relationship between the output signal level from said analog sensor and the quantity of the phenomenon from being discontinuous; and

drive means for driving a sensing element of said analog sensor to vary according to said setting signal;

whereby said sensitivity of said analog sensor is moved up to a higher level than a current level so as to accomplish a more detailed and precise detection in an area wherein such the detection is required, sensitivity of said analog sensor being lowered in the other area wherein a more rough detection than the current level is required.

15. A detector as defined in claim 14, including an amplifier for amplifying a sensing emitting signal from said sensing element of said analog sensor, said correcting means varying a threshold level of the amplifier.

16. A detector as defined in claim 15, wherein said correcting means stores and holds said sensitivity level setting signal in a readable form, said analog sensor changing characteristics of a device driving said sensing element by the sensitivity level setting signal to vary the detecting sensitivity level of said analog sensor.