US3624358A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic brake
Assignee: CHALCO ENG CORP
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Filing: 1967-05-29
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Granted: 1971-11-30
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Expires: 1987-05-29
Abstract
Abstract In order to achieve the high speed brake operation required for use in tape readers, without producing an accompanying objectionable high heat loss requiring auxiliary cooling systems for the tape reader, an induction coil having an inductance much higher than the inductance of the coils in the magnetic brakes is connected in series with a transistor and a constant current generator. One end of the brake coil is connected to the junction between the induction coil and a transistor. The brake coils are in series with a second transistor and the brake coils and the second transistor are in parallel with the first transistor. Appropriate circuitry is provided for causing the first transistor to become conductive while the second transistor becomes nonconductive and means are provided for causing these transistors to change their mode each time an appropriate pulse is applied to the circuitry. When the first transistor becomes nonconductive, interruption of the current in the induction coil produces a large voltage at the junction of the inductance coil and the first transistor. This high voltage rise is very rapid because of the rapid interruption of the current in the coil (L di/dt). Consequently, the high voltage connected across the brake coils abruptly actuates them. When a brake off pulse is applied to the circuitry, the second transistor becomes nonconductive and the first transistor becomes conductive. This in turn causes the energy in the brake coils to discharge through the second transistor.
Inventors
- 👤 Jeffrey M Bevis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:51
CPC Classifications
G; G06; G06K; G06K13/00; G06K13/18; G06K13/20; G06K13/22; G06K13/26
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
274 words
In a tape reader having means for reading perforations on the tape and means for driving the tape, magnetically actuated brakes, said brakes including brake coils, and an electric circuit connected to said brake coils, said electric circuit having a low internal resistance energy storing element for rapidly increasing the current flow through the brake coils without substantial heat loss so that the brakes may be actuated rapidly enough to permit the tape to be stopped and started at speeds up to 1,000 times per second and so auxiliary cooling equipment for the tape reader will not be required, said electric circuit comprising a first coil, said first coil in series with said brake coils, firs and second electrical switches serving as alternate action switch means so that when said first switch is closed said second switch is open and when said second switch is closed said first switch is open, said first switch connected to the junction of the first coil and said brake coils and serving to short out said brake coils when the first switch is closed, said second switch providing an alternate path for said electric current when said first switch is open and said second switch is momentarily closed, said first coil having an inductance very much greater than the inductance of said brake coil, and said means for simultaneously opening said first switch and closing said second switch when the brakes are to be applied whereby electromagnetic energy stored in said first coils produces a high voltage across the brake coils causing a very rapid current buildup in the brake coils whereby the brakes can be actuated rapidly.
Claim 2
Dependent Claim
274 words
In a tape reader having means for reading perforations on the tape and means for driving the tape, magnetically actuated brakes, said brakes including brake coils, and an electric circuit connected to said brake coils, said electric circuit having a low internal resistance energy storing element for rapidly increasing the current flow through the brake coils without substantial heat loss so that the brakes may be actuated rapidly enough to permit the tape to be stopped and started at speeds up to 1,000 times per second and so auxiliary cooling equipment for the tape reader will not be required, said electric circuit comprising a first coil, said first coil in series with said brake coils, firs and second electrical switches serving as alternate action switch means so that when said first switch is closed said second switch is open and when said second switch is closed said first switch is open, said first switch connected to the junction of the first coil and said brake coils and serving to short out said brake coils when the first switch is closed, said second switch providing an alternate path for said electric current when said first switch is open and said second switch is momentarily closed, said first coil having an inductance very much greater than the inductance of said brake coil, and said means for simultaneously opening said first switch and closing said second switch when the brakes are to be applied whereby electromagnetic energy stored in said first coils produces a high voltage across the brake coils causing a very rapid current buildup in the brake coils whereby the brakes can be actuated rapidly.
Claim 3
Dependent Claim
82 words
ThE tape reader described in claim 1 wherein said first and second electrical switches are first and second transistors, said transistors connected together in such a way that when one transistor is conductive the other transistor is nonconductive, and means for suddenly causing one transistor to become conductive and the other nonconductive when brakes are to be applied and for suddenly causing said one transistor to become nonconductive and said other transistor to become conductive when the brakes are to be released.
Claim 4
Dependent Claim
92 words
The tape reader described in claim 2 including a constant current generator in series with the first coil for causing a constant electric current to flow through said first coil when said one transistor is conductive, said first coil functioning as a circuit generator when said first transistor suddenly becomes nonconductive, whereby a current equal in magnitude to said predetermined current from said constant current generator suddenly flows to said brake coils permitting said brake coils to be operated rapidly when said first transistor becomes conductive and said second transistor becomes nonconductive.
Claim 5
Dependent Claim
138 words
The tape reader described in claim 3 wherein said electric circuit includes a bistable circuit, said bistable circuit having one terminal for receiving a brake on pulse and another terminal for receiving a brake off pulse, a control transistor, said brake on pulse causing said control transistor to become conductive, and when the brake off pulse is applied to another terminal said bistable circuit flips to another stable position causing said control transistor to become nonconductive, said control transistor connected to said first and second transistors in such a way that when said control transistor becomes nonconductive said first transistor becomes nonconductive and said second transistor becomes conductive causing the brakes to be applied, and when said control transistor becomes conductive said first transistor becomes conductive and said second transistor becomes nonconductive causing said brakes to be released.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-29 | 1975-05-31 | 1975-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-29 | 1979-05-31 | 1979-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-29 | 1983-05-31 | 1983-11-30 | $7700.00 | Window Closed / Lapsed |