Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1995-10-12
2001-12-11
Nguyen, Thinh (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S244000
Reexamination Certificate
active
06330017
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a light emitting diode (LED) array head. The invention relates, more particularly, to an LED array head including focusing lenses for use in an optical writing system of an optical printer, a digital copying machine, a facsimile machine or other printing device.
2. Discussion of the Background
LED elements are more reliable for use under vibrations and noises than laser beam printers (LBP). They are also suitable for miniaturizing an optical head since an apparatus with an LED array head does not need a scanning mechanism such as a polygonal mirror as needed by an LBP using a semiconductor laser.
On the other hand, the LED elements have problems. For example, the quality of light from each element is dispersive and beam spot shapes are not uniform. The dispersed quality of light and the lack of uniformity of the beam spot shapes generate an uneven dot density of an output image such as an image containing black stripes. This unevenness becomes more remarkable in multi-valued images such as picture images. These problems generally originate from a unit magnification focusing element of a rod lens array.
FIG. 10
illustrates a conventional rod lens array which is made up of a plurality of rod lenses
104
. These lenses may be made of fiber optic elements
104
which may be unit magnification focusing elements. The rod lenses
104
may be constructed as illustrated in
FIG. 11
in which a fiber optic element
104
is illustrated as having a cladding
110
and a core
112
. In
FIG. 11
, it is illustrated that the light reflects between the boundary of the cladding and the core. An alternative embodiment of the rod lens
104
is illustrated in
FIG. 12
which shows a gradient index lens. In this Figure, it is seen that the light does not sharply reflect within the fiber optic lens
104
but the direction of the light is smoothly changed as illustrated in FIG.
12
.
The disadvantages of the rod lens arrays including arrays which use gradient index lenses are caused by two problems. First, a dispersed light loss may occur at connecting portions between the rod lenses. This light loss occurs near the connecting portions due to a difference in a p itch of emitting elements and that of focusing elements. Second, it is difficult to uniformly converge light beams since flared light such as reflected light in a rod lens easily occurs.
FIG. 13
illustrates a conventional roof mirror lens array. In this system, light originating at
120
, is reflected off of a mirror
122
through a lens
124
, off of a roof mirror array
126
, back through the lens
124
, and off of a lower surface of the mirror
122
in order to form the image
128
. This focusing system also has the above two problems.
SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide a novel LED array head having a light emitting pattern which is uniform. It is a further object to have a small size LED array head.
These and other objects of the invention are accomplished by a light emitting diode array head including a plurality of LED chips, each containing a row of LEDs. The LEDs of each chip emit light to a corresponding lens. The lenses correspond to the LED chips on a one-to-one basis and each of the lenses may be joined to form a unitary device.
Shields may be used to prevent light from one chip from imparting on a neighboring lens in order to prevent dispersion of the quality of light in order to obtain uniform beam shapes. The lenses may be constructed to correct for spherical aberrations in order to obtain a planar focusing surface.
The LEDs may be arranged on each of the chips at varying angles so each of the LEDs directly faces the center of the lens so that the emitted light may be condensed in the center of the lens.
If the LED chips are separated such that the distance between the LEDs of the ends of different chips differ from the pitch within a chip, the system may be arranged so that the lenses magnify the light passing therethrough.
REFERENCES:
patent: 5023442 (1991-06-01), Taniguchi et al.
patent: 5444520 (1995-08-01), Murano
patent: 5475416 (1995-12-01), Kessler et al.
English Abstract of JP 60-32373, “Lateral Light Emitting Light Emitting Diode Array, Structure”, Feb. 1985.
“An Image Device Using a Roof Mirror Lens Array”, Toshiyuki Inokuchi, Ricoh Technical Report No. 13, May 1985, pp. 30-37, (Includes English Abstract).
Catalog from Nippon Sheet Glass Co. Ltd., Cat.SLA, vol. 2, Jul. 1985, pp. 2, 16-22.
English Abstract of JP 60-90784, “Printer Utilizing Light-Emitting Diode”, May 1985.
English Abstract of JP 60-90783, “Optical Printer”, May 1985.
English Abstract of JP 60-90782, “Printer Utilizing Light-Emitting Diode”, May 1985.
English Abstract of JP 60-116479, “Printer Using Light-Emitting Diode”, Jun. 1985.
English Abstract of JP 60-99673, “Printer Using Light Emitting Diode”, Jun. 1985.
English Abstract of JP 60-99672, “Printer Using Light Emitting Diode”, Jun. 1985.
Nguyen Thinh
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh Co. Ltd.
LandOfFree
Light emitting diode array head including focusing lenses does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Light emitting diode array head including focusing lenses, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light emitting diode array head including focusing lenses will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2591271