Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1997-12-29
2001-02-20
Le, N. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S237000, C347S130000
Reexamination Certificate
active
06191804
ABSTRACT:
BACKGROUND OF THE INVENTION
1.Field of the Invention
The present invention relates to an image forming apparatus, and in particular, to a multi-beam image forming apparatus such as a copier or a printer that forms an image with a plurality of laser beams for improvement in image forming speed.
2.Description of the Related Art
Due to a need for printing a high-quality image with high resolution and at high speed, a multi-beam image forming apparatus, which is made to scan in parallel the surface of a drum photoconductor by a plurality of laser beams, is being tested for realization in a latest image forming apparatus of electrophotographic type. Such a multi-beam image forming apparatus has a significant technical problem in practical use. That is, the problem is how the light-and-shade difference among image lines formed by the laser beams can be harmoniously adjusted.
More specifically, in the multi-beam image forming apparatus, a distortion occurs in an electric current due to a stray capacitance existing in a driving element supplying a driving electric current to a laser diode, in its electric current passageway and the like, rendering it difficult to adjust an image density. Moreover, since a fluctuation occurs in the image density for each dot and a moire occurs in the formed image, it is difficult to solve the problem of image quality by merely adjusting the driving electric current for each laser diode.
SUMMARY OF THE INVENTION
The present invention has been made under such circumstances and aims to provide an image forming apparatus, which can decrease the undesirable effect due to a stray capacitance existing in the environments of each driving element, electric current passageways, and the like, and in which the density of image formed by each beam can be easily adjusted by reforming the electric current waveform, and substantially no moiré is produced.
Accordingly, the present invention provides an image forming apparatus comprising: a plurality of light-emitting elements, each light-emitting element receiving a driving current from a power supply and converting the current into a beam; a plurality of driving elements, each driving element being interposed between the power supply and each light-emitting element and controlling the driving current based on an image signal; and a photoconductor on which the beams from the plurality of light-emitting elements form an image by scanning, wherein each light-emitting element is positioned so adjacent to each driving element that a power leakage factor floating between the light-emitting element and the driving element is reduced, whereby an intensity of the beam is substantially equivalent to the image signal in waveform.
The feature that the light-emitting element is positioned adjacent to the driving element means that the distance between the both elements is designed to be smaller than several centimeters to minimize a wiring from the light-emitting element to the driving element. This can be realized by mounting the light-emitting element and the driving element on a single printed circuit board, for example. Here, the power leakage factor includes at least one of a stray capacitance, a stray conductance, and a stray inductance.
REFERENCES:
patent: 5515136 (1996-05-01), Nishio et al.
patent: 5815025 (1998-09-01), Kubota
patent: 6008833 (1998-09-01), Ohtsubo et al.
patent: 57-106230 (1982-07-01), None
patent: 4-323052 (1992-11-01), None
Ishigami Masahide
Iwasa Masayuki
Kaneko Fumio
Kitagawa Shunji
Matsuo Hiroyuki
Armstrong, Westerman Hattori, McLeland & Naughton
Fujitsu Limited
Le N.
Nguyen Lamson D.
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