US4897639A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image forming method and apparatus
Assignee: Fujifilm Corp
•
Filing: 1988-05-02
•
Granted: 1990-01-30
•
Expires: 2008-05-02
Abstract
Abstract Multiple light-emitting diodes in an array are supplied with a constant amount of electric current and the duration of time for which that current is supplied to the individual light-emitting diodes is changed according to the specific level of contrast to be produced. The amount of light received by a light-sensitive material can thus be controlled so that a halftone image is formed. The duration of time for which the electric current is applied to the individual light-emitting diodes consists of a predetermined constant portion and a variable portion to be added thereto. The variable portion is compensated for in accordance with the difference between the relative intensities of light emission from the individual light-emitting diodes when they are supplied with the constant electric current. As a result, the amounts of light emission from the individual light-emitting diodes are rendered sufficiently uniform to effectively compensate for the variation in the intensity of light emission from the individual diodes.
Inventors
- 👤 Toshikiyo Kanayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:23
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/401; H04N1/4015
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
144 words
An image-forming apparatus comprising: a plurality of arrays of light-emitting diodes, each of said arrays of light-emitting diodes being arranged in a first direction, said arrays being parallel to one another and facing a light sensitive material; a plurality of lenses, one lens for each of said arrays, interposed between one of said arrays and said light sensitive material; frame memory means for storing contrast data for each of said light emitting diodes in said arrays; pulse width modulating means receiving said contrast data from said frame memory means and generating pulse signals with durations proportional to said contrast data; compensating means receiving said pulse signals and adjusting the duration of said pulse signals in accordance with compensating data; and drive means for supplying current to each of said light emitting diodes of said arrays in accordance with the output of said compensating means.
Claim 2
Dependent Claim
144 words
An image-forming apparatus comprising: a plurality of arrays of light-emitting diodes, each of said arrays of light-emitting diodes being arranged in a first direction, said arrays being parallel to one another and facing a light sensitive material; a plurality of lenses, one lens for each of said arrays, interposed between one of said arrays and said light sensitive material; frame memory means for storing contrast data for each of said light emitting diodes in said arrays; pulse width modulating means receiving said contrast data from said frame memory means and generating pulse signals with durations proportional to said contrast data; compensating means receiving said pulse signals and adjusting the duration of said pulse signals in accordance with compensating data; and drive means for supplying current to each of said light emitting diodes of said arrays in accordance with the output of said compensating means.
Claim 3
Dependent Claim
112 words
An image-forming apparatuses claimed in claim 1, wherein said pulse width modulating means comprises: line memory means for storing a line of contrast data from said frame memory; first counter means for counting a first clock signal and for supplying an address to said line memory means; second counter means for counting second clock signal and providing second counter outputs representing different contrast values; comparator means for comparing the output of said line memory means with the output of said second counter means; shift register means for storing outputs produced by said comparator means; and latch means responsive to said second clock signal for latching the contents of said shift register means.
Claim 4
Dependent Claim
47 words
An image-forming apparatus as claimed in claim 2, wherein said compensating means comprises: compensating data storage means for storing said compensating data; and compensation processing means for processing the logical data in said latch means based on the compensating data stored in said compensating data storage means.
Claim 5
Dependent Claim
116 words
An image-forming apparatus as claimed in claim 3, wherein said compensation processing means comprises: a plurality of shift registers for receiving said compensating data corresponding to respective ones of said diodes; a plurality of counting means presettable in accordance with the compensating data held in respective ones of said shift registers; a plurality of flip-flop circuits each of which is reset by the output of one of said plurality of presettable counting means, and all of which are set by receiving a gate signal; and a plurality of AND circuit means for combining the outputs of said latch means and the outputs of said plurality of flip-flop circuits, to obtain said output of said compensating means.
Claim 6
Dependent Claim
36 words
An image-forming apparatus as claimed in claim 4, further comprising: a further AND circuit means for combining a third clock signal and said gate signal and supplying an output to an input of said counting means.
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) | 1993-01-29 | 1993-07-31 | 1994-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-29 | 1997-07-31 | 1998-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-29 | 2001-07-31 | 2002-01-30 | $7700.00 | Window Closed / Lapsed |