US3909681A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Driving circuit for printing electromagnet
Assignee: Bull HN Information Systems Italia SpA
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Filing: 1974-11-19
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Granted: 1975-09-30
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Expires: 1994-11-19
Abstract
Abstract This disclosure relates to a driving circuit for driving a coil of an electromagnet for the actuation of a hammer in a high speed impact printer of data handling systems, which driving circuit includes first switching means upstream of the coil, second switching means downstream of the coil, current sensing means for sensing current in the coil, a closed unidirectional current path including the second switching means, the coil in a diode, first control circuit means for actuating the first switching means in response to an input control signal, second control circuit means for switching on the second switching means in response to the first input control signal and for the entire duration of the input control signal, and a bistable device triggered by the current sensing means to assume one of two electrical states when the sensed current reaches a predetermined value and to provide an output signal corresponding to that one state, the output signal being effective to switch off the first switching means even in the presence of the input control signal.
Inventors
- 👤 Alfredo Campari
- 👤 Giorgio Vigini
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:33
CPC Classifications
H; H01; H01F; H01F7/00; H01F7/06; H01F7/08; H01F7/18; H01F7/1883; B; B41; B41J; B41J9/00; B41J9/44
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
185 words
Driving circuit for driving an electromagnet coil with a controlled current comprising: first switching means upstream of said coil and connected thereto; second switching means downstream of said coil and connected thereto, current sensing means connected to said coil for sensing the current in said coil; a closed unidirectional current path including said second switching means, said coil and a diode; first control circuit means connecteD to said first switching means for actuating said first switching means in response to an input control signal; second control circuit means connected to said second switching means for switching on said second switching means in response to said input control signal and for the entire duration of said input control signal; a bistable device connected to and triggered by said current sensing means to assume one of two electrical states when the sensed current reaches a preestablished value and to provide an output signal corresponding to said one state, said output signal being connected to said first control circuit means and effective to switch off said first switching means even in the presence of said input control signal.
Claim 2
Dependent Claim
185 words
Driving circuit for driving an electromagnet coil with a controlled current comprising: first switching means upstream of said coil and connected thereto; second switching means downstream of said coil and connected thereto, current sensing means connected to said coil for sensing the current in said coil; a closed unidirectional current path including said second switching means, said coil and a diode; first control circuit means connecteD to said first switching means for actuating said first switching means in response to an input control signal; second control circuit means connected to said second switching means for switching on said second switching means in response to said input control signal and for the entire duration of said input control signal; a bistable device connected to and triggered by said current sensing means to assume one of two electrical states when the sensed current reaches a preestablished value and to provide an output signal corresponding to said one state, said output signal being connected to said first control circuit means and effective to switch off said first switching means even in the presence of said input control signal.
Claim 3
Dependent Claim
61 words
Driving circuit as claimed in claim 1 further comprising overvoltage detecting means to detect an overvoltage due to the switching off of said unidirectional current path and to provide an overvoltage signal, said overvoltage signal being applied to said bistable device, said bistable device being reset in that one of the electrical states other than said one by said overvoltage signal.
Claim 4
Dependent Claim
25 words
Driving circuit as claimed in claim 1 wherein there is a voltage detector connected to said coil between said coil and said first switching means.
Claim 5
Dependent Claim
30 words
Driving circuit as claimed in claim 3 wherein there is voltage signal means connected to and operated in response to the condition of said bistable device for diagnosing element failure.
Claim 6
Dependent Claim
30 words
Driving circuit as claimed in claim 1 wherein there is voltage signal means connected to and operated in response to the condition of said bistable device for diagnosing element failure.
Claim 7
Dependent Claim
35 words
Driving circuit as claimed in claim 1 wherein said first control circuit means includes a transformer having a primary winding, and demagnetization means for said primary winding including means defining an unidirectional short circuit path.
References Cited (Backward Citations)
US3205412A
Cited
US3206651A
Cited
US3235775A
Cited
US3582734A
Cited
US3549955A
Cited
US3859572A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |