Optical printer and print head thereof

Details Optical printer and print head thereof Optical printer and print head thereof

2000-02-04

2002-06-11

Pham, Hai C. (Department: 2861)

Incremental printing of symbolic information

Light or beam marking apparatus or processes

Scan of light

C347S241000, C347S256000

Reexamination Certificate

active

06404454

ABSTRACT:

FIELDS OF THE INVENTION
The present invention generally relates to an optical printer for example, a fixed, a portable printer and the like, for optical writing on a recording medium; and more particularly to an optical printer and a print head therefor, wherein a plurality of filters are selectively alternated or changed with respect to a common luminous source.
BACKGROUND OF THE INVENTION
As is well known, a print head in a typical optical printer includes a luminous source in which a plurality of fine luminous dots are juxtaposed along a line, the luminous source moving from a main scanning direction juxtaposing to the luminous dots to a sub-scanning direction perpendicular to the main scanning direction so as to irradiate dot-type lights on a recording medium, forming a desired image thereon. A variety of luminous elements such as a fluorescent luminous tube or LED and the like are utilized as the luminous source.
There is schematically shown in
FIG. 14
a structure of a print head incorporated in a conventional optical printer, for example, a portable color printer and the like and there is shown in
FIG. 15
a partial structure of the print head, with some parts omitted therefrom.
As shown in
FIG. 14
, a print head
100
is made to reciprocate in a sub-scanning direction, e.g., with respect to a film
102
acting as a recording medium placed at a predetermined position. That is, as shown in
FIG. 15
, the print head
100
is guided by a pair of guide shafts
104
which are positioned parallel to the sub-scanning direction and is connected to a pulse motor
106
through a wire
108
to be driven, thereby allowing the print head
100
to reciprocate in the sub-scanning direction. Further, the print head
100
includes a luminous element
110
acting as a luminous source, the luminous element
110
having a plurality of luminous dots that are positioned parallel to the main scanning direction. Light emitted from the luminous element
110
passes through three filters R,G,B as described hereinafter and is imaged through a reflective optical element(mirror)
112
, a single optical system(lens)
114
, and a reflective optical element (mirror)
116
to the film
102
.
As shown in
FIG. 14
, each of the red filter R, the green filter G and the blue filter B is disposed on an irradiating side of the luminous element
110
to be alternated or changed as desired. As shown in
FIG. 15
, the three filters R,G,B are mounted on a common filter holder
118
in such a way that longer sides thereof are parallel to the main scanning direction and shorter sides are parallel to the sub-scanning direction. The filter holder
118
is provided with a projection
120
for manipulating the filter holder
118
, the projection
120
projecting in the sub-scanning direction. Also, the projection
120
is maintained between a guide bearing
122
and a position determining bearing
124
. The position determining bearing
124
is biased by a spring
126
and engaged with any one of three cut-off portions
128
formed on the projection
120
. The filter holder
118
is compressed by a spring
130
toward a predetermined direction in the sub-scanning direction. An abutment
132
is disposed at a predetermined distance from the projection
120
and a reset plate
134
is disposed at an opposite side therefrom in such a manner that the print head
100
is sandwiched therebetween. That is, when the projection
120
of the filter holder
118
comes in contact with the abutment
132
as a result of the print head
100
moving, the filter holder
118
also moves, allowing the filters R,G,B to be alternated or changed as desired. Further, when the print head
100
is moved in an opposite direction as described above, resulting in the reset plate
134
shifting a shaft
136
of the position determining bearing
124
, the engagement of the filter holder
118
is released by the position determining bearing
124
and the spring
130
allows the filter holder
118
to move toward a direction of the abutment
132
.
A writing operation on the film
102
using the above-described structure will be described using FIG.
16
. There is shown in
FIG. 16
a moving chart of the print head
100
. As shown, reference numeral “a” indicates a filter reset position, a region between reference numerals “b” and “c” is referred to as an accelerating region, a region between reference numerals “c” and “d” is an exposure region, and a region between reference numerals “d” and “f” is a change-over region of the filters R,G,B. Further, &Dgr; marks in the drawing is referred to as a position of the luminous source
110
, i.e., a luminous dot row. In the above-described print head
100
, a full-color image is formed on the film
102
by color-separating an image into three images of primary colors of R,G,B and superposing the three images.
As shown in
FIG. 16
, the reset plate
134
moves the shaft
136
of the position determining bearing
124
when the print head
100
is moved to the “a” position, which, in turn, results in the filter holder
118
moving to right by the elastic force of the spring to be reset at an initial position. At this position, the filter R is set at a light irradiating position (referred to as &Dgr; mark) of the luminous element
110
.
The printer head
100
, as shown in
FIG. 16
, accelerates at a regular speed through the accelerating region, i.e., between “b” and “c” along the sub-scanning direction and moves to the exposure region, i.e., between “c” and “d”. In synch with this operation, the luminous element
110
is driven with an image signal of red R, forming the image in red R on the film.
Furthermore, at the completion of the forming of the image in red R on the film, the projection
120
of the filter holder
118
comes in contact with the abutment
132
at the changing-over region, allowing the filter holder
118
to move and the filter to change-over from red R to green G.
Next, the print head
100
moves to the “b” position. At this position, since the reset plate
134
and the shaft
136
of the position determining bearing
124
are not in contact with each other, the filters are not reset. The print head, as shown in
FIG. 16
, is accelerated at the regular speed through the accelerating region along the subscanning direction and moves to the exposure region. In synch with this operation, the luminous element
110
is driven with an image signal of green G, forming an image in green G on the film. At the completion of the forming of the image in green on the film, the projection
120
of the filter holder
118
comes in contact with the abutment
132
at the change-over region, i.e., between “e” and “f”, allowing the filter holder
118
to move and causing the filter to change-over from green G to blue B.
Again, the print head
100
moves to “b” position. At this position, since the reset plate
134
and the shaft
136
of the position determining bearing
124
are not in contact with each other, the filters are not reset. Further, the print head
100
, as shown in
FIG. 16
, is accelerated at the regular speed through the accelerating region and moves to the exposure region. In synch with this operation, the eluminous element
110
is driven with an image signal of blue B, forming an image in blue B on the film.
Next, the print head
100
moves to the “a” position as shown in
FIG. 16
, the reset plate
134
and the shaft
136
of the filter holder
124
come in contact with each other and the filter is reset as red R.
As described above, in the conventional optical printer, the print head
100
is movable in the sub-scanning direction with respect to the film
102
placed at a desired position. Further, the print head
100
is constructed in such a way that the change-overs among the filters R,G,B being movable in the sub-scanning direction, are accomplished only by the movement thereof.
However, in the conventional optical printer as described, the change-over from green G to blue B takes place when the print head
100
moves and comes in contact with the abutment
132
shown at the righ

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