US3676680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ionization fire alarm with insulation monitoring system
Assignee: Cerberus AG
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Filing: 1970-06-08
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Granted: 1972-07-11
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Expires: 1990-06-08
Abstract
Abstract An ionization fire alarm comprising a measuring ionization chamber which is connected in series with at least one resistance element, preferably constructed as a reference ionization chamber, at a voltage source. An electrical amplifier and/or threshold value detector circuit is also provided, the input of which is electrically coupled with the junction point of the measuring ionization chamber and the resistance element. According to an important aspect of the invention the electric circuit of the ionization fire alarm system is constructed such that a signal is released when the input potential exceeds an upper threshold value or drops below a lower threshold value.
Inventors
- 👤 Andreas Scheidweiler
- 👤 Otto Meier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:43
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/10; G08B17/11
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
116 words
An ionization fire alarm comprising an electrical circuit containing a voltage supply, a measuring ionization chamber including a pair of electrodes, and a series connected resistance element coupled to said voltage supply, electrical response means having its input coupled with the junction point of said measuring ionization chamber and series connected resistance element, said electrical response means including means for monitoring the insulation resistance between the electrodes of said ionization chamber, and further including means for releasing a signal when the input potential at said junction point exceeds an upper threshold value or drops below a predetermined threshold value which is below the normal operating potential at said junction point caused by a decreasing insulation resistance.
Claim 2
Dependent Claim
116 words
An ionization fire alarm comprising an electrical circuit containing a voltage supply, a measuring ionization chamber including a pair of electrodes, and a series connected resistance element coupled to said voltage supply, electrical response means having its input coupled with the junction point of said measuring ionization chamber and series connected resistance element, said electrical response means including means for monitoring the insulation resistance between the electrodes of said ionization chamber, and further including means for releasing a signal when the input potential at said junction point exceeds an upper threshold value or drops below a predetermined threshold value which is below the normal operating potential at said junction point caused by a decreasing insulation resistance.
Claim 3
Dependent Claim
22 words
An ionization fire alarm as defined in claim 1, wherein said series connected resistance element is defined by a reference ionization chamber.
Claim 4
Dependent Claim
17 words
An ionization fire alarm as defined in claim 1, wherein said electrical response means comprises amplifier means.
Claim 5
Dependent Claim
20 words
An ionization fire alarm as defined in claim 1, wherein said electrical response means comprises threshold value detector circuit means.
Claim 6
Dependent Claim
24 words
An ionization fire alarm as defined in claim 1, wherein said signal releasing means delivers a disturbance signal similar to the normal alarm signal.
Claim 7
Dependent Claim
22 words
An ionization fire alarm as defined in claim 5, wherein said electrical circuitry comprises a four junction semi-conductor possessing two control electrodes.
Claim 8
Dependent Claim
94 words
An ionization fire alarm as defined in claim 5, wherein said electrical response means comprises two components, the first component releasing a signal when the voltage drop across the measuring ionization chamber exceeds a predetermined value, and the second components releasing a signal when the voltage drop across the measuring ionization chamber falls below a different predetermined value, and wherein said electrical circuit a four junction semi-conductor with two control electrodes, each respective control electrode of said four junction semi-conductor being electrically coupled with the output of a respective one of said two components.
Claim 9
Dependent Claim
26 words
An ionization fire alarm as defined in claim 1, wherein said signal releasing means releases a disturbance signal which is different from the normal alarm signal.
Claim 10
Dependent Claim
20 words
An ionization fire alarm as defined in claim 8, wherein both of said signals consist of direct-currents of different magnitude.
Claim 11
Dependent Claim
26 words
An ionization fire alarm as defined in claim 8, wherein one signal is a direct-current signal and the otheR signal is composed of an alternating-current signal.
Claim 12
Dependent Claim
25 words
An ionization fire alarm as defined in claim 8, wherein one signal is a direct-current signal and the other signal is an interrupted direct-current signal.
Claim 13
Dependent Claim
39 words
An ionization fire alarm as defined in claim 1, having a second threshold value above the normal operating potential, the current flow through said electric circuitry is almost zero when the input potential is between said two threshold potentials.
Claim 14
Dependent Claim
28 words
An ionization fire alarm as defined in claim 1, wherein said electrical circuitry comprises only two conductors for coupling the ionization fire alarm with a central signal station.
Claim 15
Dependent Claim
65 words
An ionization fire alarm as defined in claim 1, wherein said electrical response means comprises two components arranged in said electrical circuit such that the first component releases a signal when the voltage drop across said measuring ionization chamber exceeds a predetermined value, and said second component releases a signal when the voltage drop across said measuring ionization chamber falls below a different predetermined value.
Claim 16
Dependent Claim
54 words
An ionization fire alarm as defined in claim 14, wherein said first component is constructed as a cold cathode tube having a control electrode electrically coupled with the input side of said electrical circuitry, and said second component is constructed as a glow discharge lamp connected in parallel to said series connected resistance element.
Claim 17
Dependent Claim
59 words
An ionization fire alarm as defined in claim 14, wherein both of said components are combined into a mechanical unit in the form of a cold cathode-glow thyratron possessing two ignition paths, one ignition path being coupled in parallel to the measuring ionization chamber and the other ignition path being connected in parallel to said series connected resistance element.
Claim 18
Dependent Claim
19 words
An ionization fire alarm as defined in claim 14, wherein both of said components are constructed as field-effect transistors.
Claim 19
Dependent Claim
59 words
An ionization fire alarm as defined in claim 17, wherein both field-effect transistors are complementary type transistors, each of said field-effect transistors possessing a gate electrode, said gate electrodes of both field-effect transistors being electrically coupled with the input side of said electrical circuitry, and both field-effect transistors being blocked when the input potential is between the threshold values.
Claim 20
Dependent Claim
86 words
An ionization fire alarm as defined in claim 18, wherein in addition to both of said complementary field-effect transistors, said electric circuit incorporates a third transistor as well as an additional resistance element which is connected in series with said measuring ionization chamber and said first-mentioned series connected resistance, the collector-emitter path of said third transistor being arranged parallel to said measuring ionization chamber and said first-mentioned series connected resistance, said third transistor being in circuit with and operatively controlled by one of both field-effect transistors.
Claim 21
Dependent Claim
71 words
An ionization fire alarm as defined in claim 19, wherein said electrical circuit is additionally provided with an emitter resistance in circuit with said one field-effect transistor operatively controlling said third transistor and a fourth transistor, the collector-emitter path of which is disposed parallel to said emitter resistance of said field-effect transistor operatively controlling said third transistor, said fourth transistor being in circuit with and operatively controlled by said third transistor.
Claim 22
Dependent Claim
29 words
An ionization fire alarm as defined in claim 20, wherein the base of said fourth transistor is additionally in circuit with and operatively controlled by the other field-effect transistor.
Claim 23
Dependent Claim
42 words
An ionization fire alarm as defined in claim 20, wherein said other field-effect transistor is connected in series with a switching element, said switching element triggering a switching operation when the input potential at said junction point falls below a predetermined value.
Claim 24
Dependent Claim
16 words
An ionization fire alarm as defined in claim 22, wherein said switching element comprises a relay.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |