EP0067937A2
Expired / Lapsed
EP
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Multi-chopping drive circuit for an electromagnetic print hammer or the like
Assignee: International Business Machines Corp
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Filing: 1982-04-15
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Granted: —
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Expires: 2002-04-15
Abstract
Abstract A constant energy drive circuit comprises two interconnected chopping circuits (19, 21-24 and 26-30) successively operable to control the current in a coil (10) of an electromagnetic actuator. One chopping circuit (19, 21-24) operates during the rise time portion of the operating interval, the other (26-30) operates beginning with the occurrence of a predetermined peak current and for remainder of the operating interval of fixed duration.
Inventors
- 👤 Robert Walker Arnold
- 👤 Dean William Skinner
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 16:35
CPC Classifications
B; B41; B41J; B41J9/00; B41J9/44; H; H01; H01H; H01H47/00; H01H47/22; H01H47/32; H01H47/325
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
138 words
A drive circuit for supplying a fixed amount of energy to a coil (10) of an electromagnetic actuator for a print hammer or the like, comprising switch means (11, 14) for connecting said coil across a voltage source (Vl), characterized by means (16, 17) for enabling said switch means for energizing said coil for an operating interval of fixed duration, first chopping circuit means (19, 21-24) operable in response to the varying current in said coil for cycling said switch means at a first frequency during the fixed rise time portion of said operating interval, and second chopping circuit means (26-30) activated at a predetermined peak current in said coil for cycling said switch means at a second frequency so as to maintain a desired average current in said coil during the remaining portion of said operating interval.
Claim 2
Dependent Claim
138 words
A drive circuit for supplying a fixed amount of energy to a coil (10) of an electromagnetic actuator for a print hammer or the like, comprising switch means (11, 14) for connecting said coil across a voltage source (Vl), characterized by means (16, 17) for enabling said switch means for energizing said coil for an operating interval of fixed duration, first chopping circuit means (19, 21-24) operable in response to the varying current in said coil for cycling said switch means at a first frequency during the fixed rise time portion of said operating interval, and second chopping circuit means (26-30) activated at a predetermined peak current in said coil for cycling said switch means at a second frequency so as to maintain a desired average current in said coil during the remaining portion of said operating interval.
Claim 3
Dependent Claim
95 words
The drive circuit of claim 1, wherein said first chopping circuit means includes a first comparison means (19) for comparing a current signal from said coil (10) corresponding with said varying current in said coil with a varying reference signal for cycling said switch means (11, 14) during said fixed rise time interval at said first frequency, and said second chopping circuit means includes a second comparison means (26) for comparing said current signal from said coil with a predetermined peak reference level signal for initiating cycling of said switch means at said second frequency.
Claim 4
Dependent Claim
57 words
The drive circuit of claim 2, wherein said first chopping circuit means further includes waveform generating means (22, 23) for producing said varying reference signal, and said varying reference signal from said waveform generating means increases at a predetermined rate to said predetermined peak reference level signal during said fixed rise time portion of said operating interval.
Claim 5
Dependent Claim
37 words
The drive circuit of claim 3, wherein said varying reference signal from said waveform generating means (22, 23) increases exponentially to said predetermined reference peak level signal during said fixed rise time portion of said operating interval.
Claim 6
Dependent Claim
51 words
The drive circuit of claim 4, wherein said waveform generating means for producing said exponentially increasing reference signal includes an RC circuit means (22, 23) connected to said predetermined reference voltage (VR), said RC circuit including means (21) connected to supply said varying reference signal to said first comparison means (19).
Claim 7
Dependent Claim
34 words
The drive circuit of claim 3, wherein said varying reference signal increases at a predetermined constant rate to said predetermined peak reference level signal during said fixed rise time portion of said operating interval.
Claim 8
Dependent Claim
38 words
The drive circuit of claim 6, wherein said waveform generating means includes a current source (I c ), said current source having a connection (36, 21) to said first comparison means (19) for supplying said varying reference signal.
Claim 9
Dependent Claim
60 words
The drive circuit of claim 1, wherein said first chopping circuit means (19, 21-24) cycles said switch means (10, 14) at a faster rate than said second chopping circuit means, said second chopping circuit means (26-30) cycling said switch means so as to maintain a desired average current in said coil (10) for said remaining portion of said operating interval.
Claim 10
Dependent Claim
53 words
A constant energy drive circuit for an operating coil (10) of a print hammer or the like, comprising a pair of interconnected chopping circuits (19, 21-24; 26-30) operable individually for chopping the current in said coil during successive fixed use time and steady state portions of a coil energizing interval of fixed duration.
Claim 11
Dependent Claim
53 words
A constant energy drive circuit for an operating coil (10) of a print hammer or the like, comprising a pair of interconnected chopping circuits (19, 21-24; 26-30) operable individually for chopping the current in said coil during successive fixed use time and steady state portions of a coil energizing interval of fixed duration.
Claim 12
Dependent Claim
75 words
The constant energy drive circuit of claim 9, wherein a first chopper (19, 21-24) is operable during the rise time portion of an operating interval of fixed duration for supplying a first fixed amount of the total predetermined energy supplied to said coil (10), and a second chopper circuit (26-30) is operable during the remaining portion of said operating interval for supplying a second fixed amount of said total predetermined energy supplied to said coil.
References Cited (Backward Citations)
No citation records indexed.
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