Optical printer device that forms color images

Details Optical printer device that forms color images Optical printer device that forms color images

2001-10-10

2004-04-13

Pham, Hai (Department: 2861)

Incremental printing of symbolic information

Light or beam marking apparatus or processes

Scan of light

C347S256000

Reexamination Certificate

active

06720986

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical printer device that forms color images by converting electrical signals to color optical signals.
2. Description of the Related Art
A video printer is a printer that prints images, which have been digitally processed and which are shown on a display, on a sheet. Known printing methods, which are adopted for video printers, include the thermal method, inkjet method, laser-beam scanning method and the liquid-crystal shutter method. Among such methods, the liquid-crystal shutter method is suitable for the purposes of obtaining a very small and lightweight device.
An optical printer device having a liquid-crystal shutter according to prior art is described below using
FIGS. 7
to
9
.
As shown in
FIG. 7
, a light-source unit for this video printer comprises a pair of members
32
, which are each arranged facing one another at a predetermined interval in a horizontal direction (the X-Y direction in FIG.
7
). A support member
31
is suspended between these members
32
such that the upper end of the hollow portion, which is formed between members
32
, is occupied by this support member
31
.
The lengthwise direction of support member
31
(a direction perpendicular to the surface of the paper of
FIG. 7
) corresponds to the direction of a single line on a photosensitive member
16
. A plurality of light-emitting elements are arranged on the lower face of support member
31
. Light-emitting diodes (hereinafter referred to as LEDs) are used for these light-emitting elements. These light-emitting elements (LEDs) are described hereinbelow by referring to FIG.
8
.
As shown in
FIG. 8
, an R light (red light) LED
30
R, B light (blue light) LED
30
B and G light (green light) LED
30
G are provided close to one another in a direction (X-Y direction) that is orthogonal to the single-line direction of photosensitive material
16
. Light-emitting element groups
33
are constituted by these LEDs
30
R,
30
G,
30
B, which are aligned to form one row in the X-Y direction of
FIG. 8. A
plurality of light-emitting element groups
33
are arranged at a predetermined pitch (normally on the order of about 3 mm) in the single-line direction of photosensitive material
16
(a direction perpendicular to X-Y of FIG.
8
).
As shown in
FIG. 7
, a cylindrical lens
34
is mounted at the lower end of the above-mentioned hollow portion that is formed by the pair of members
32
. Further, below this cylindrical lens
34
, a liquid-crystal optical shutter array
36
is provided as a optical shutter array.
Next, control of liquid-crystal optical shutter array
36
will be described using FIG.
9
. For the sake of convenience in the description, the single line of photosensitive material
16
will be considered to correspond to one pixel column that comprises five pixels. Consequently, one liquid-crystal cell column of liquid-crystal shutter array
36
comprises five liquid-crystal cells. This liquid-crystal array
36
comprises four liquid-crystal cell columns arranged in a direction that is orthogonal (in the X-Y direction) to the single-line direction of these liquid-crystal cell columns. In other words, liquid-crystal shutter array
36
comprises twenty liquid-crystal cells, which are arranged in five columns and four rows. Hereinbelow, a liquid-crystal cell in column i (i=1 to 5) and row j (j=1 to 4) is represented by
36
SRij. Further, in
FIG. 9
, liquid-crystal cells
36
Sij, through which R light, which is emitted from LED
30
R, is transmitted, are distinguished using oblique lines.
When transportation of photosensitive material
16
begins such that the first single line is exposed, as shown in FIG.
9
(
a
), liquid-crystal cells
36
S
41
,
36
S
43
,
36
S
45
, which are in the fourth liquid-crystal cell column (liquid-crystal cells
36
S
41
to
36
S
45
), are open (pattern P
1
). Then, after this line exposure using G light and B light is complete, same having been emitted from LEDs
30
G and
30
B, respectively, a transport roller (not shown in the figure) is driven to transport photosensitive material
16
by a distance of one line in the X direction of FIG.
9
.
Then, when photosensitive material
16
is exposed by R light, which is emitted for a second time from LED
30
R, as shown in FIG.
9
(
b
), liquid-crystal cells
36
S
31
,
36
S
33
,
36
S
35
in the third liquid-crystal cell column (liquid-crystal cells
36
S
31
to
36
S
35
) are open on the basis of a pattern P
1
, and liquid-crystal cells
36
S
42
,
36
S
44
in the fourth liquid-crystal cell column are open on the basis of a pattern P
2
.
As described hereinabove, in the above-mentioned technique, R-light LEDs, B-light LEDs and G-light LEDs on support member
31
are each fixed in a predetermined column and predetermined row. As a result, when displacement occurs, of the positions of R light, B light and G light on photosensitive material
16
, from these predetermined positions, since no adjustment is possible of the corresponding mount positions of R-light LEDs, B-light LEDs and G-light LEDs on support member
31
, positions of R light, B light and G light cannot be matched with these predetermined positions.
In addition, due to the fact that exposure of photosensitive material
16
is performed one line at a time, there is a problem in that the image-formation speed is low.
SUMMARY OF THE INVENTION
In accordance with an aspect of the present invention, an optical printer of the present invention has an exposure device which makes relative movement in a predetermined direction with respect to a photosensitive body.
The exposure device comprises a first mounting substrate for mounting a plurality of first light-emitting elements which emit light of a first color, a second mounting substrate for mounting a plurality of second light-emitting elements which emit light of a second color, and a third mounting substrate for mounting a plurality of third light-emitting elements which emit light of a third color, in addition to a frame.
The exposure device further comprises an optical shutter which controls the passage of the light from the first, second and third light-emitting elements to change the amount of irradiation onto the photosensitive body.
The first, second and third mounting substrates are configured independent of one another, respectively, and are attached to the frame.


REFERENCES:
patent: 5444520 (1995-08-01), Murano
patent: 5712674 (1998-01-01), Doi
patent: 6249502 (2001-06-01), Mushiake
patent: 6549226 (2003-04-01), Shimizu et al.
patent: 0 831 640 (1998-03-01), None
patent: 63-189264 (1988-08-01), None
patent: 7-306481 (1995-11-01), None
patent: 2000-158709 (2000-06-01), None
Patent Abstracts of Japan, Publication No. 56140319, Publication Date Feb. 11, 1981; Application No. 55043881, Application Date Mar. 4, 1980.

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