Patent US4501591A successfully refreshed from Google Patents.
US4806031A
Expired / Lapsed
US
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Uniform print density and registration in an impact printer
Assignee: Ricoh Printing Systems America Inc
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Filing: 1986-08-15
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Granted: 1989-02-21
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Expires: 2006-08-15
Abstract
Abstract Commencing with the first print hammer(s) "out", or actuated, on each print line the hammer drive current is boosted 10% for a period, ranging from 25%=650 microseconds for single part forms to 50% for multi-part forms, of the total print hammer flight time. Earlier striking hammers on each print line strike harder, alleviating displaced first-printed characters on single part forms and light characters on multipart forms due to hammer energy loss in forms compression.
Inventors
- 👤 Paul O. Amdahl
- 👤 John K. Ham
- 👤 Doina Mazilu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:03
CPC Classifications
B; B41; B41J; B41J9/00; B41J9/44; B41J9/48
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
114 words
In an impact printer in which plural hammers sequentially strike a paper form to print each line, the improvement comprising: means for imparting to the first print hammer to strike said paper form in the printing of each line a higher energy than that imparted to other hammers used in printing that line, said higher energy being available for a predetermined time period to subsequently actuated print hammers in successively decreasing amounts according to proximity in time of the firing of the subsequent print hammers to the firing of the first print hammer, said higher energy being in compensation for the loss of impact energy due to movement of the paper by said hammers.
Claim 2
Dependent Claim
114 words
In an impact printer in which plural hammers sequentially strike a paper form to print each line, the improvement comprising: means for imparting to the first print hammer to strike said paper form in the printing of each line a higher energy than that imparted to other hammers used in printing that line, said higher energy being available for a predetermined time period to subsequently actuated print hammers in successively decreasing amounts according to proximity in time of the firing of the subsequent print hammers to the firing of the first print hammer, said higher energy being in compensation for the loss of impact energy due to movement of the paper by said hammers.
Claim 3
Independent Claim
102 words
An apparatus for increasing the current drive to a print hammer first striking a workpiece form in each line printed by an impact printer, said apparatus comprising: current drive means, controllable in the level of current drive, for supplying current drive to a multiplicity of print hammers; and boost means for controlling said current drive means to supply increased current drive to that print hammer first striking a workpiece form in each line printed by an impact printer, said boost means making the increased current drive available for a predetermined time period to subsequently actuated print hammers for successively decreasing time periods.
Claim 4
Independent Claim
102 words
An apparatus for increasing the current drive to a print hammer first striking a workpiece form in each line printed by an impact printer, said apparatus comprising: current drive means, controllable in the level of current drive, for supplying current drive to a multiplicity of print hammers; and boost means for controlling said current drive means to supply increased current drive to that print hammer first striking a workpiece form in each line printed by an impact printer, said boost means making the increased current drive available for a predetermined time period to subsequently actuated print hammers for successively decreasing time periods.
Claim 5
Dependent Claim
65 words
The apparatus according to claim 2 wherein said boost means further comprises: boost means responsive to the normal, unincreased level of current drive for controlling said current drive means to supply increased current drive for a relatively shorter time when said normal level of current drive is relatively lower, and for a relatively longer time when said normal level of current drive is relatively higher.
Claim 6
Dependent Claim
43 words
The apparatus according to claim 2 wherein said boost means further comprises: boost means for controlling said current drive means to supply increased current drive for a predetermined fractional portion of the flight time of that print hammer first striking said workpiece form.
Claim 7
Dependent Claim
30 words
The apparatus according to claim 4 wherein said predetermined fractional portion of the flight time is within the range of 25% to 50% of the total print hammer flight time.
Claim 8
Independent Claim
110 words
A method for obtaining uniform print density across a line printed by an impact printer, said method comprising: sensing a first actuation of at least one of a multiplicity of print hammers the printing of each line; and responsively to said sensing the first actuation, boosting the drive of said at least one first actuated print hammer in order that it strikes a workpiece form being printed harder than later actuated print hammers; and boosting the drive of successively actuated print hammers in successively smaller boost amounts until, at some stage of successive actuations of groups of print hammers, no boost is provided to the drive of said print hammers.
Claim 9
Independent Claim
110 words
A method for obtaining uniform print density across a line printed by an impact printer, said method comprising: sensing a first actuation of at least one of a multiplicity of print hammers the printing of each line; and responsively to said sensing the first actuation, boosting the drive of said at least one first actuated print hammer in order that it strikes a workpiece form being printed harder than later actuated print hammers; and boosting the drive of successively actuated print hammers in successively smaller boost amounts until, at some stage of successive actuations of groups of print hammers, no boost is provided to the drive of said print hammers.
Claim 10
Dependent Claim
16 words
The method according to claim 6 wherein said boosting further comprises: boosting said drive approximately 10%.
Claim 11
Dependent Claim
42 words
The method according to claim 6 wherein said boosting further comprises: boosting said drive for a time duration within the range of 25% to 50% of the total time of the drive of each said one or more first actuated print hammers.
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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) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |