US3632986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control system
Assignee: Applied Automation Inc
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Filing: 1970-05-18
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Granted: 1972-01-04
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Expires: 1990-05-18
Abstract
Abstract A temperature-sensing thermistor and a heating element are positioned in a region of temperature to be controlled. The thermistor is connected in a bridge circuit, the output of which charges a capacitor. The voltage on the capacitor controls the firing of a thyristor which passes current to the heating element. Means are provided for discharging the capacitor periodically.
Inventors
- 👤 Harold M Neer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:43
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/20; G05D23/24; G05D23/1906
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
168 words
Temperature control apparatus comprising: an electrical heating element; a temperature-sensing element adapted to be positioned in a region of temperature to be controlled; a source of alternating current; a bidirectional thyristor having a gate electrode; means connecting said thyristor and said heating element in circuit with said source of alternating current; a capacitor; circuit means including said temperature sensing element to establish a current, the magnitude of which is representative of the temperature sensed by said sensing element; means to apply the current established by said circuit means to said capacitor to charge same; trigger circuit means connected between said capacitor and the gate electrode of said thyristor to cause said thyristor to conduct when said capacitor is charged to a predetermined potential; and means connected to said capacitor and said source of alternating current to provide a circuit path independent of said circuit means to discharge said capacitor at the end of each half cycle of potential applied across said thyristor from said source of alternating current.
Claim 2
Dependent Claim
168 words
Temperature control apparatus comprising: an electrical heating element; a temperature-sensing element adapted to be positioned in a region of temperature to be controlled; a source of alternating current; a bidirectional thyristor having a gate electrode; means connecting said thyristor and said heating element in circuit with said source of alternating current; a capacitor; circuit means including said temperature sensing element to establish a current, the magnitude of which is representative of the temperature sensed by said sensing element; means to apply the current established by said circuit means to said capacitor to charge same; trigger circuit means connected between said capacitor and the gate electrode of said thyristor to cause said thyristor to conduct when said capacitor is charged to a predetermined potential; and means connected to said capacitor and said source of alternating current to provide a circuit path independent of said circuit means to discharge said capacitor at the end of each half cycle of potential applied across said thyristor from said source of alternating current.
Claim 3
Dependent Claim
21 words
The apparatus of claim 1 wherein said trigger circuit means comprises a trigger diode connected between said capacitor and said thyristor.
Claim 4
Dependent Claim
63 words
The apparatus of claim 1 wherein said means to discharge comprises a transistor connected Between said capacitor and ground, and means connected to said source of alternating current to cause said transistor to be nonconductive except at the end of each half cycle of said alternating current when the potential applied across said thyristor is zero, at which time said transistor is conductive.
Claim 5
Dependent Claim
98 words
The apparatus of claim 3 wherein said means to cause said transistor to be nonconductive comprises a resistor and a first diode connected in series across said source of alternating current, means including a second diode connected between the junction between said resistor and first diode and said transistor to cause said transistor to be nonconductive when a potential of first polarity exists at said junction, and means including a second transistor connected between said junction and the first-mentioned transistor to cause said first-mentioned transistor to be nonconductive when a potential of second polarity exists at said junction.
Claim 6
Dependent Claim
80 words
The apparatus of claim 4 wherein each of said transistors has an emitter, a collector and a base, the base of said second transistor is connected to said junction, said second diode is connected between the base and collector of said second transistor, the emitters of said transistors are connected to ground, the collector of said second transistor is connected to the base of said first-mentioned transistor, and including means connecting the collector of said first-mentioned transistor to said capacitor.
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) | 1975-01-03 | 1975-07-05 | 1976-01-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-03 | 1979-07-05 | 1980-01-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-03 | 1983-07-05 | 1984-01-04 | $7700.00 | Window Closed / Lapsed |