US4885597A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Non-impact printer apparatus with improved current mirror driver and method of printing
Assignee: Eastman Kodak Co
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Filing: 1988-12-27
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Granted: 1989-12-05
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Expires: 2008-12-27
Abstract
Abstract An improved printer apparatus includes a print head having a series of point-like radiation sources, such as LED's, arranged in a row for exposing a recording medium. Logic means is provided for determining which of the point-like radiation sources are to be selected for energization. A current driver means responsive to the logic means provides electrical current to the radiation sources selected. A current driver means include a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the radiation sources selected for energization. The master circuit includes a series of parallel connected transistors that may be instantaneously reprogrammed by digital control signals to said transistors. The characteristics of the transistors vary so that currents from them are scaled by say powers of two to provide an expanded current control capability. Environmental conditions and/or aging often require change in current to maintain desired recording performance. The need for such change may be automatically sensed and a new digital control word sent to the transistors to adjust current to the radiation sources.
Inventors
- 👤 Pin S. Tschang
- 👤 Hieu T. Pham
- 👤 Kenneth D. Kieffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:51
CPC Classifications
G; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1238; G06K15/1242; G06K15/1247
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
160 words
In a printing apparatus for exposing a radiation sensitive recording medium; a print head including a series of point-like radiation sources arranged in a row for exposing the medium, means for moving the medium relative to the print head; means providing data signals representing data to be printed; logic means responsive to the data signals for determining which of the point-like radiation sources are to be selected for energization; current driver means responsive to the logic means for providing electrical current to the radiation sources selected for energization; wherein the current driver means includes a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the radiation sources selected for energization; the master circuit being characterized by a plurality of individually addressable current regulating devices; and digital control means for digitally addressing each such current regulating device to control the level of current in the master circuit.
Claim 2
Dependent Claim
160 words
In a printing apparatus for exposing a radiation sensitive recording medium; a print head including a series of point-like radiation sources arranged in a row for exposing the medium, means for moving the medium relative to the print head; means providing data signals representing data to be printed; logic means responsive to the data signals for determining which of the point-like radiation sources are to be selected for energization; current driver means responsive to the logic means for providing electrical current to the radiation sources selected for energization; wherein the current driver means includes a current mirror having a master circuit for generating a reference current and a plurality of slave circuits for providing respective driver currents to the radiation sources selected for energization; the master circuit being characterized by a plurality of individually addressable current regulating devices; and digital control means for digitally addressing each such current regulating device to control the level of current in the master circuit.
Claim 3
Dependent Claim
15 words
The apparatus of claim 1 and wherein the current regulating devices are arranged in parallel.
Claim 4
Dependent Claim
13 words
The apparatus of claim 2 and wherein the current regulating devices are transistors.
Claim 5
Independent Claim
36 words
The apparatus of claims 1, 2 or 3 and wherein the current regulating devices have respective control terminals and different current carrying capabilities when activated by a similar signal at each of their respective control terminals.
Claim 6
Dependent Claim
21 words
The apparatus of claim 4 and wherein the control terminals of the current regulating devices have different width to length ratios.
Claim 7
Dependent Claim
47 words
The apparatus of claim 5 and wherein there are N+1 current regulating devices in a master circuit, N being an integer greater than or equal to one, and the ratio of the respective currents conducted through the devices are: 2.sup.N :2.sup.N-1 :. . . 2.sup.2 :2.sup.1 :2.sup.0.
Claim 8
Dependent Claim
22 words
The apparatus of claim 6 and wherein the digital addressing means includes means for controlling the current in response to environmental conditions.
Claim 9
Dependent Claim
60 words
The apparatus of claim 7 and wherein the printing apparatus includes a plurality of current driver means each for driving respective radiation sources, the digital addressing means controlling current in response to local environmental conditions for the respective radiation sources driven by a driver means so that current to the radiation sources is adjusted in accordance with local environmental conditions.
Claim 10
Dependent Claim
17 words
The apparatus of claim 7 and including temperature sensing means for sensing the temperature of the printhead.
Claim 11
Dependent Claim
24 words
The apparatus of claim 6 and wherein the digital addressing means includes means for controlling the current in response to aging of the printhead.
Claim 12
Independent Claim
25 words
The apparatus of claims 1, 2 or 3 and wherein the digital addressing means includes means for controlling the current in response to environmental conditions.
Claim 13
Dependent Claim
45 words
The apparatus of claim 1 and wherein the slave circuit for each radiation source includes a respective transistor and wherein the master circuit includes means for providing a first voltage bias to the respective transistors to cause same to conduct with controlled levels of current.
Claim 14
Dependent Claim
46 words
The apparatus of claim 12 and wherein the master circuit includes a first transistor and a second transistor, the second transistor establishing the said first voltage bias in response to both a voltage bias associated with said transistor and the current passing through the second transistor.
Claim 15
Dependent Claim
31 words
The apparatus of claim 13 and wherein the current passing through the second transistor is related to which of the current regulating devices are addressed to cause current to flow therethrough.
Claim 16
Dependent Claim
15 words
The apparatus of claim 14 and wherein the current regulating devices are arranged in parallel.
Claim 17
Dependent Claim
13 words
The apparatus of claim 15 and wherein the current regulating devices are transistors.
Claim 18
Independent Claim
34 words
The apparatus of claims 12, 13, 14, 15 or 16 and wherein the current regulating devices have different current carrying capabilities when activated by a similar signal at each of their respective control terminals.
Claim 19
Dependent Claim
18 words
The apparatus of claim 17 and wherein the current regulating devices have different gate width to length ratios.
Claim 20
Dependent Claim
47 words
The apparatus of claim 18 and wherein there are N+1 current regulating devices in a master circuit, N being an integer greater than or equal to one, and the ratio of the respective currents conducted through the devices are: 2.sup.N :2.sup.N-1 :. . . 2.sup.2 :2.sup.1 :2.sup.0.
Claim 21
Dependent Claim
24 words
The apparatus of claim 18 and wherein the digital addressing means includes means for controlling the current in response to temperature of the printhead.
Claim 22
Dependent Claim
24 words
The apparatus of claim 18 and wherein the digital addressing means includes means for controlling the current in response to aging of the printhead.
Claim 23
Independent Claim
54 words
The apparatus of claims 13 or 14 and including means for adjusting the voltage bias associated with said first transistor said adjusting means including a plurality of individually addressable current regulating devices and digital control means for digitally addressing each such current regulating device to control the level of current in the master circuit.
Claim 24
Dependent Claim
57 words
The apparatus of claim 1 wherein a slave circuit comprises a second current regulating means for controlling current to a radiation source selected for energization and the digitally addressed current regulating devices establish an adjustable voltage bias upon the second current regulating means which determines the level of current provided to a radiation source selected for energization.
Claim 25
Dependent Claim
130 words
In a method of printing by exposing a radiation sensitive recording medium to radiation from a series of point-like radiation sources arranged in a row for exposing the medium; the steps of moving the medium relative to the radiation sources; providing data signals representing data to be printed for determining which of the point-like radiation sources are to be selected for energization providing electrical current to the radiation sources selected for energization; generating in a master circuit a reference current and in a plurality of slave circuits providing respective driver currents to the radiation sources selected for energization; the method being characterized by individually addressing current regulating devices in the master circuit; and digitally addressing each such current regulating device to control the level of current in the master circuit.
Claim 26
Dependent Claim
130 words
In a method of printing by exposing a radiation sensitive recording medium to radiation from a series of point-like radiation sources arranged in a row for exposing the medium; the steps of moving the medium relative to the radiation sources; providing data signals representing data to be printed for determining which of the point-like radiation sources are to be selected for energization providing electrical current to the radiation sources selected for energization; generating in a master circuit a reference current and in a plurality of slave circuits providing respective driver currents to the radiation sources selected for energization; the method being characterized by individually addressing current regulating devices in the master circuit; and digitally addressing each such current regulating device to control the level of current in the master circuit.
References Cited (Backward Citations)
US4746841A
Cited
US4831392A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-04 | 1993-06-05 | 1993-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-04 | 1997-06-05 | 1997-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-04 | 2001-06-05 | 2001-12-05 | $7700.00 | Window Closed / Lapsed |