Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-11-25
2003-02-18
Nghiem, Michael (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
Reexamination Certificate
active
06522350
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an imaging apparatus and an imaging method using beam irradiation sources such as laser beam sources, and preferably to an apparatus and its method for generating a change in an imaging characteristic (physical change) such as projections and depressions or a change in solubility to solvent on an imaging medium such as an imaging film, an imaging plate according to imaging data using a beam digitally controlled. Also, the present invention relates to an optical fiber array apparatus and an imaging head apparatus, which are used in the above imaging apparatus. Moreover, the present invention relates to a printing apparatus using the above imaging apparatus.
BACKGROUND ART
FIG. 61
shows an example of an imaging apparatus using beam irradiation sources such as laser beam source. As described in Unexamined Japanese Patent Publication No. 6-186750 (corresponding to U.S. Pat. No. 5,339,737), an imaging apparatus
9
comprises a medium support drum
91
for winding an imaging medium around on its outer surface, an imaging head
92
including beam irradiation sources and an optical system for condensing beams from the beam irradiation sources, a beam irradiation source control unit
96
, and a cable
95
for connecting the imaging head
92
to the beam-irradiation source control unit
96
. Moreover, the imaging head
92
is fixed onto a linear stage
94
for realizing a parallel movement with respect to an axial direction of the medium support drum
91
.
As the linear stage
94
, a linear motor typed linear stage, which is directly driven by a linear motor, and a ball screw typed linear stage using a ball screw typed linear guide are generally used. The distance between the imaging head
92
and the imaging medium
98
is adjusted such that the beams are condensed on the surface of the imaging medium. The outputs of the beam irradiation sources-are controlled enough to generate a change in an imaging characteristic (physical change) such as projections and depressions according to imaging data or a change in solubility to solvent between a beam irradiation section of the imaging medium
98
and a non-irradiation section.
In executing the imaging, the beam irradiation sources are switched to correspond to imaging data as performing the following operations. Specifically, the medium support drum
91
around which the imaging medium
98
is wound is rotated in a direction of an arrow R of the figure using a motor
93
such as a pulse motor. Also, the imaging head
92
fixed onto the linear stage
94
is moved in a direction of an arrow S of the figure to be parallel to the shaft of the medium support drum. This generates a two-dimensional change in an imaging characteristic (physical change), such as physical projections and depressions according to imaging data or a change in solubility to solvent, on the surface of the imaging medium.
Generally, a direction R of lines imaged by the rotation of the medium support drum
91
is defined as a main scanning direction, and a direction S of lines imaged by the parallel movement of the imaging head
92
is defined as a sub-scanning direction.
As the method for improving the performance of such the imaging apparatus, there can be easily considered the plurality of beam irradiation sources, which can be independently driven.
The improvement of the performance of the imaging apparatus means to enhance the imaging speed and resolution. The relationship of tradeoff is established between the imaging speed and the resolution. In this case, the resolution denotes that how many dots can be formed per unit length, and dpi (dots per inch) is generally used as a unit.
For example, 2540 dpi corresponds to 100 dots/mm. As one example, suppose that the imaging head having i beam irradiation sources is used to execute imaging i lines continuous to the main scanning direction simultaneously by i beam irradiation sources. At this time, a dot distance d
p
for realizing a predetermined resolution r is 1/r. Then, when the linear motor typed linear stage is used, in many cases, the imaging head is moved by a predetermined distance after the imaging corresponding to one circumference in the main scanning direction is finished. When the ball screw typed linear stage is used, the imaging head is moved by a predetermined distance during one turn of the medium support drum. The predetermined distance is i times as large as the dot distance d
p
on the imaging medium.
Thereafter, next i lines are imaged, and these series of operations are repeated, and the imaging of the entire surface of the imaging area is completed. By use of i beam irradiation sources, the time required for imaging is reduced to 1/i when the resolution is the same.
In order to increase the resolution j times, it is needed that the dot distance be set to d
p
/j and that the distance of the movement of the imaging head be set to d
p
×i/j. Then, time required for imaging results in J/i times.
As one of the methods using the plurality of beam irradiation sources, a laser diode array is used. The general outline view is shown in FIG.
39
.
A laser diode array
8
includes eight laser diodes, which can be independently driven, in one chip. The laser diodes have laser beam emission ends
81
a
to
81
h,
drive side electrodes
82
a
to
82
h,
and a rear face common electrode
83
for all laser diodes, respectively. The flow of a predetermined current to the drive side electrodes
82
a
to
82
h
allows the laser beam to be emitted from the corresponding laser beam emission ends
81
a
to
81
h.
In this case, the predetermined current means a current value of more than a threshold value at which the laser diode starts the laser oscillation.
As another method using the plurality of beam irradiation sources, the fiber array is used. The outline view of a fiber output laser apparatus is shown in FIG.
42
.
A laser apparatus
6
comprises a laser diode chip having at least one light emission end, a conductive_member for realizing the electrical contact between an electrode of the diode chip and an outer unit, a package section
61
having a heat conduction member for escaping heat from the diode chip to the outside and an optical system for making the laser beams incident onto the optical fibers from the laser diode, and an optical fiber
62
for guiding laser beams to the outer unit.
Then, the laser beam is emitted from an emission end
63
of the optical fiber
62
. As shown in
FIG. 58
, the emission end
63
of the optical fiber
62
has a core portion
64
and a clad portion
65
, and the laser beam is output from the core portion
64
. Then, the emission ends
63
of the plurality of fibers of the laser device of the plurality of fiber outputs are arranged in an array form and fixed, thereby structuring the fiber array. When the fiber array is used as the beam irradiation sources, the maximum distance between the beam irradiation sources is restricted by an outside dimension of the clad portion
65
.
In many cases, it is impossible to arrange the beam irradiation sources, that is, the respective emission ends, to be close to each other without any space in either of the methods of the laser diode array and the fiber array. In order to perform the imaging in the imaging area of the imaging medium without any space, the array must be inclined to the sub-scanning direction S by a predetermined angle &thgr; as shown in FIG.
6
. An array
7
comprises eight beam irradiation sources
71
a
to
71
h,
and its inclination angle &thgr; is defined by the following equation (1).
cos &thgr;=d
s
/a
s
(1)
where a
s
is a distance between the beam irradiation sources, a light source surface dot distance d
s
obtained by converting the central distance between dots, which should be formed to obtain a predetermined resolution in the sub-scanning direction S, to the dimension-at the beam irradiation source surface, and the medium surface dot distance d
p
is divided by a magnification of the optical system.
For example, d
p
=10 &mgr;m wh
Inoue Yoshinori
Iwai Hiroaki
Morgan & Lewis & Bockius, LLP
Nghiem Michael
Toray Industries Inc.
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