US4727428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for compensation of LED-array output power variation in electrophotographic printing
Assignee: Panasonic System Solutions Japan Co Ltd
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Filing: 1986-12-01
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Granted: 1988-02-23
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Expires: 2006-12-01
Abstract
Abstract In a method and an apparatus for compensation of any variation that occurs in the output power or luminous energy of a LED array used in electrophotographic printing, the time for applying a current to one line of the LED array is optimally divided into a fundamental on-time for constant current application to the individual elements of the LED array and a compensational on-time for selective current application thereto in such a manner that the exposure values on a photosensitive medium become uniform.
Inventors
- 👤 Kiyoshi Futatsugi
- 👤 Inui Yasuo
- 👤 Mitsuo Mochizuki
- 👤 Akira Hichijou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:47
CPC Classifications
G; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1238; G06K15/1242; G06K15/1247; G01; G01N; G01N35/00; G01N2035/00465; G01N2035/00564
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
123 words
A method of compensating any variation in LED-array output power by controlling a current on-time for individual LED array elements in such a manner that the exposure values thereof on a photosensitive medium become uniform, said method comprising: determining a current on-time relative to one line of the LED array by setting a fundamental on-time for constant current application to the individual LED array elements and at least one compensational on-time for selective current application thereto; dividing the luminous energy distribution of said LED array into 2 n parts where n represents the set number of the compensational on-time; and attaining a coincidence between the maximum and minimum luminous energies in each of the divided 2 n parts of said luminous energy distribution.
Claim 2
Independent Claim
123 words
A method of compensating any variation in LED-array output power by controlling a current on-time for individual LED array elements in such a manner that the exposure values thereof on a photosensitive medium become uniform, said method comprising: determining a current on-time relative to one line of the LED array by setting a fundamental on-time for constant current application to the individual LED array elements and at least one compensational on-time for selective current application thereto; dividing the luminous energy distribution of said LED array into 2 n parts where n represents the set number of the compensational on-time; and attaining a coincidence between the maximum and minimum luminous energies in each of the divided 2 n parts of said luminous energy distribution.
Claim 3
Dependent Claim
50 words
An apparatus for carrying out the method defined in claim 1, wherein picture data is stored in a line memory and, during a one-line scanning operation, the picture data is read out a number of times equal to the set number of said fundamental current on-time and compensational current on-time.
Claim 4
Dependent Claim
27 words
An apparatus for carrying out the method defined in claim 1, wherein said compensational current on-time is controlled in accordance with compensational data stored in a ROM.
Claim 5
Dependent Claim
39 words
An apparatus for carrying out the method defined in claim 1, wherein the time of current application from a driver circuit to the LED array is divided in response to a STB (strobe) signal fed to a latch circuit.
Claim 6
Dependent Claim
40 words
An apparatus for carrying out the method defined in claim 1, wherein the time of current application from a driver circuit to the LED array is controlled by the use of an ENB (enable) signal fed to said driver circuit.
Claim 7
Independent Claim
120 words
A method of compensating any variation in LED-array output power by controlling a current on-time for individual LED array elements in such a manner that the exposure values thereof on a photosensitive medium become uniform, said method comprising: determining a current on-time relative to one line of the LED array by setting a fundamental on-time for constant current application to the individual LED array elements and at least one compensational on-time for selective current application thereto; dividing the luminous energy distribution of said LED array into 2 n parts where n represents the set number of the compensational on-time; and minimizing the difference between the maximum and minimum values in the entire 2 n parts of the luminous energy distribution.
Claim 8
Independent Claim
120 words
A method of compensating any variation in LED-array output power by controlling a current on-time for individual LED array elements in such a manner that the exposure values thereof on a photosensitive medium become uniform, said method comprising: determining a current on-time relative to one line of the LED array by setting a fundamental on-time for constant current application to the individual LED array elements and at least one compensational on-time for selective current application thereto; dividing the luminous energy distribution of said LED array into 2 n parts where n represents the set number of the compensational on-time; and minimizing the difference between the maximum and minimum values in the entire 2 n parts of the luminous energy distribution.
Claim 9
Dependent Claim
50 words
An apparatus for carrying out the method defined in claim 6, wherein picture data is stored in a line memory and, during a one-line scanning operation, the picture data is read out a number of times equal to the set number of said fundamental current on-time and compensational current on-time.
Claim 10
Dependent Claim
27 words
An apparatus for carrying out the method defined in claim 6, wherein said compensational current on-time is controlled in accordance with compensational data stored in a ROM.
Claim 11
Dependent Claim
39 words
An apparatus for carrying out the method defined in claim 6, wherein the time of current application from a driver circuit to the LED array is divided in response to a STB (strobe) signal fed to a latch circuit.
Claim 12
Dependent Claim
40 words
An apparatus for carrying out the method defined in claim 6, wherein the time of current application from a driver circuit to the LED array is controlled by the use of an ENB (enable) signal fed to said driver circuit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-22 | 1991-08-24 | 1992-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-22 | 1995-08-24 | 1996-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-22 | 1999-08-24 | 2000-02-23 | $7700.00 | Window Closed / Lapsed |