US4243875A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature control for resistance heating element
Assignee: Individual
•
Filing: 1978-11-13
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Granted: 1981-01-06
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Expires: 1998-11-13
Abstract
Abstract A temperature control system for a resistance element which is heated by a power supply connected to it by a switching member, the switching member being controlled by an electronic circuit which is operative to produce alternate ON-cycles and OFF-cycles whose durations are controlled by separate time constants. The durations of these alternate cycles respectively set the higher and lower temperature limits within which the heating element temperature remains. The electronic circuitry further provides a single initial ON-cycle of greater duration which occurs only when the circuit is newly turned ON and operates to bring the resistance element up to operating temperature from ambient temperature, an indicator being provided to glow during each ON-cycle interval. The control system is illustrated for use with a soldering iron which is supportable in a cradle connected with a switch to turn OFF the system when the iron rests in the cradle.
Inventors
- 👤 Daniel C. Chang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:52
CPC Classifications
G; G05; G05D; G05D23/00; G05D23/19; G05D23/1906; G05D23/1913; B; B23; B23K; B23K3/00; B23K3/02; B23K3/03; B23K3/033
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
322 words
A control circuit for controlling the temperature of an electric soldering iron including a cradle-operated switch for connecting a power supply to the circuit when the iron is raised from the cradle and disconnecting the supply when the iron rests on the cradle, the control circuit comprising: (a) an ON/OFF switching member connecting the power supply to the soldering iron and enabling the flow of current thereto when conductive; (b) a first monostable means having a stable state and a non-stable state and connected to render said ON/OFF switching member conductive when in said non-stable state, said first monostable means having two separate time constants each energizable separately from the other to determine when energized a longer and a shorter duration of said non-stable state; (c) a second monostable means having a stable state and a non-stable state of constant duration, the first and second monostable means being mutually interconnected and operative so that as each returns to its stable state it triggers the other to begin its non-stable state; (d) a bistable flip-flop having two stable states and having two output terminals respectively connected to said two separate time constants of the first monostable means, and the flip-flop having separate input terminals for triggering the flip-flop into one or the other of its stable states, one of said inputs being operative upon raising of the iron from the cradle and closing of said switch connecting the power supply to the circuit to energize the longer duration time constant, and the other input being coupled to the first monostable means to be triggered by the return thereof to stable state to trigger the flip-flop to energize the shorter duration time constant as long as the iron remains raised from the cradle, brief manual depressing of the cradle and release thereof actuating said one input to trigger the flip-flop to re-energize the longer time constant and raise the operating temperature of the iron.
Claim 2
Dependent Claim
322 words
A control circuit for controlling the temperature of an electric soldering iron including a cradle-operated switch for connecting a power supply to the circuit when the iron is raised from the cradle and disconnecting the supply when the iron rests on the cradle, the control circuit comprising: (a) an ON/OFF switching member connecting the power supply to the soldering iron and enabling the flow of current thereto when conductive; (b) a first monostable means having a stable state and a non-stable state and connected to render said ON/OFF switching member conductive when in said non-stable state, said first monostable means having two separate time constants each energizable separately from the other to determine when energized a longer and a shorter duration of said non-stable state; (c) a second monostable means having a stable state and a non-stable state of constant duration, the first and second monostable means being mutually interconnected and operative so that as each returns to its stable state it triggers the other to begin its non-stable state; (d) a bistable flip-flop having two stable states and having two output terminals respectively connected to said two separate time constants of the first monostable means, and the flip-flop having separate input terminals for triggering the flip-flop into one or the other of its stable states, one of said inputs being operative upon raising of the iron from the cradle and closing of said switch connecting the power supply to the circuit to energize the longer duration time constant, and the other input being coupled to the first monostable means to be triggered by the return thereof to stable state to trigger the flip-flop to energize the shorter duration time constant as long as the iron remains raised from the cradle, brief manual depressing of the cradle and release thereof actuating said one input to trigger the flip-flop to re-energize the longer time constant and raise the operating temperature of the iron.
Claim 3
Dependent Claim
22 words
A control circuit as claimed in claim 1, wherein at least one of said time constants is adjustable to set its duration.
References Cited (Backward Citations)
US2260030A
Cited
US2455453A
Cited
US2543005A
Cited
US3247358A
Cited
US3283127A
Cited
US3284721A
Cited
US3379896A
Cited
US3509322A
Cited
US3883716A
Cited
US4010412A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |