GB1489128A - Smoke detectors - Google Patents
Smoke detectorsInfo
- Publication number
- GB1489128A GB1489128A GB3633375A GB3633375A GB1489128A GB 1489128 A GB1489128 A GB 1489128A GB 3633375 A GB3633375 A GB 3633375A GB 3633375 A GB3633375 A GB 3633375A GB 1489128 A GB1489128 A GB 1489128A
- Authority
- GB
- United Kingdom
- Prior art keywords
- capacitor
- transistor
- diode
- reference voltage
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000779 smoke Substances 0.000 title abstract 4
- 239000003990 capacitor Substances 0.000 abstract 7
- 230000002238 attenuated effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 abstract 1
- 238000012986 modification Methods 0.000 abstract 1
- 230000004048 modification Effects 0.000 abstract 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
- E21F17/18—Special adaptations of signalling or alarm devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
- G01N27/66—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber and measuring current or voltage
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
- G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
Landscapes
- Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- Emergency Management (AREA)
- Business, Economics & Management (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Electrochemistry (AREA)
- Biochemistry (AREA)
- Pathology (AREA)
- Toxicology (AREA)
- Fire-Detection Mechanisms (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Immunology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Health & Medical Sciences (AREA)
Abstract
1489128 Smoke detector NOHMI BOSAI KOGYO CO Ltd 3 Sept 1975 [3 Sept 1974] 36333/75 Heading G1A In a smoke detector a comparator 24 stores a reference voltage which is compared by a differential amplifier 27 with the voltage V 1 from a photodiode 15. The effects of spurious signals (due to the occasional occurrence of flashing lights) is mitigated by a transistor 40 connected in parallel with the capacitor 24 driven by a series combination of a diode 41 capacitor 42 and resistor 43. The result is that when the first positive half wave peak of the spurious signal reaches point P the transistor 40 is switched on for a predetermined period. This drains some of the charge on the capacitor 24 so that the resulting current due to the spurious signals does not charge the capacitor 24 to past the reference voltage. The first positive half wave peak of the spurious signals also charges the capacitor 42 which slowly discharges via the reverse bias resistor of the diode 41 and which keeps the transistor 40 turned off in the meantime. The capacitor 24 is initially charged to its reference voltage via a low pass filter 20 comprising resistor 21, capacitor 22 and diode 23. The reference voltage is applied via a F.E.T. 25 to the differential amplifier 27 which receives the amplified (16) output of the photo-diode 15 which depends on the amount of light reaching it from a source 10. The beam intensity may be attenuated by the presence of smoke and when this occurs the differential amplifier 27's output changes and turns on a transistor 30 which activates a relay 32 and then a relay 35 which produces an alarm signal. Modifications of the circuits are described employing a photo-resistor, Fig. 3 (not shown), and an ionization chamber, Fig. 4 (not shown).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP49105934A JPS5057540A (en) | 1973-09-13 | 1974-09-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1489128A true GB1489128A (en) | 1977-10-19 |
Family
ID=14420666
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB3633375A Expired GB1489128A (en) | 1974-09-13 | 1975-09-03 | Smoke detectors |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1489128A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2469764A1 (en) * | 1979-08-24 | 1981-05-22 | Hochiki Co | PHOTOELECTRIC SMOKE DETECTOR |
| FR2609342A1 (en) * | 1987-01-05 | 1988-07-08 | Dupuy Claude | Optical smoke detection device |
| CN103473880A (en) * | 2013-09-23 | 2013-12-25 | 何林 | High-sensitivity smoke alarm |
| EP3799003A1 (en) * | 2019-09-24 | 2021-03-31 | Unilumin Group Co., Ltd. | Smoke detecting circuit and display panel using the same |
-
1975
- 1975-09-03 GB GB3633375A patent/GB1489128A/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2469764A1 (en) * | 1979-08-24 | 1981-05-22 | Hochiki Co | PHOTOELECTRIC SMOKE DETECTOR |
| FR2609342A1 (en) * | 1987-01-05 | 1988-07-08 | Dupuy Claude | Optical smoke detection device |
| CN103473880A (en) * | 2013-09-23 | 2013-12-25 | 何林 | High-sensitivity smoke alarm |
| CN103473880B (en) * | 2013-09-23 | 2015-09-02 | 重庆广播电视大学 | High-sensitivity smoke alarm |
| EP3799003A1 (en) * | 2019-09-24 | 2021-03-31 | Unilumin Group Co., Ltd. | Smoke detecting circuit and display panel using the same |
| US11127269B2 (en) | 2019-09-24 | 2021-09-21 | Unilumin Group Co., Ltd | Smoke detecting circuit and display panel using the same |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |