Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1998-10-09
2001-07-17
Le, N. (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S232000
Reexamination Certificate
active
06262757
ABSTRACT:
TECHNICAL FIELD
This invention relates to an optical printer apparatus for producing images by introducing relative motion of an optical head with respect to a photosensitive medium while exposing the medium under predetermined timing, and more particularly to a structure for supporting the optical head, a drive mechanism of the optical head, and an exposure timing control technique.
BACKGROUND ART
Video printers are widely used for printing onto a photosensitive sheet images digitally processed and displayed on a display. Printing methods for video printers include thermal method, ink-jet method, laser beam scanning method, and liquid crystal shutter method. Of these methods, the optical printer method, wherein the image is formed by exposure of a photosensitive medium with light from a light source under exposure timing controlled by a liquid crystal shutter, has attracted attention for its suitability to compact, lightweight designs. Prior art examples of such optical printer method are disclosed in Japanese Laid-Open Patent Application 2-287527 and 2-169270.
The prior art examples cited above will be described referring to FIG.
16
. In
FIG. 16
, a casing
11
houses a film loading section
12
that contains a film pack FP containing a plurality of sheets of self-processing film F, each being a photosensitive medium. Located adjacent to the opening
13
of the film loading section
12
is a set of transport rollers
16
comprising a pair of rim drive rollers
14
a
and
14
b
for drawing out by gripping therewith a predetermined single sheet of film F, which has been exposed, from the film pack FP housed in the film loading section
12
and a pair of ironing rollers
15
a
and
15
b
for developing the exposed film F.
An exposing and recording section
17
for producing the image on the film F is disposed between the rim drive roller pair
14
a
and
14
b
and the ironing roller pair
15
a
and
15
b.
The exposing and recording section
17
includes a light source
18
such as a halogen lamp, and is designed so that the film F is exposed to the light from this light source
18
through an optical fiber bundle
19
, color filters (not shown) of three colors (RGB) disposed parallel to the image auxiliary scanning direction, a liquid crystal light valve
20
, and a gradient index lens array
21
.
A polarizing plate is disposed above and below and to the sides of the liquid crystal light valve
20
with the direction of polarization thereof oriented parallel. A first glass substrate is disposed to the inside of the polarizing plate, one face of this first glass substrate being provided through vacuum evaporation with thin films consisting of coloring matters of three different colors (R, G, and B) that serve as color filters (not shown). The other face is provided with transparent electrodes arranged along the color filters (not shown), i.e., a plurality of pixel electrodes disposed in linear fashion in the auxiliary scanning direction.
Liquid crystals such as twisted nematic liquid crystals are sealed between the pixel electrodes and a second glass substrate. At the interface of the second glass substrate with the liquid crystals, a common electrode, being a transparent electrode, is produced through vacuum evaporation at the side of the second glass substrate. The aforementioned polarizing plate is located on the other side of the second glass substrate; light passing through this polarizing plate is directed through the gradient index lens array
21
for the exposure of the film F.
The prior art described above, however, lacks means for accurately controlling the relative motion of the photosensitive medium and the exposure light, and thus has the drawback of image distortion caused by deviation in the speed of relative motion of the photosensitive medium and the exposure light.
Accordingly, it is an object of the present invention to provide an optical printer apparatus that overcomes the aforementioned drawbacks of optical printer apparatuses of the prior art, by assuring a constant relative motion speed of photosensitive medium and exposure light over the entire scanning area, thereby affording images that are free from distortion.
It is a further object of the present invention to provide an optical printer apparatus equipped with a head support structure capable of stably supporting over the entire scanning area the optical head that emits the exposure light.
DISCLOSURE OF THE INVENTION
An optical printer apparatus comprising an optical head for irradiating a photosensitive medium with exposure light in order to produce an image and a motor for introducing relative motion of the optical head and the photosensitive medium over a predetermined scanning area, the optical head and the photosensitive medium being induced to undergo relative motion at a predetermined speed in order to produce an image on the photosensitive medium, wherein the optical printer apparatus further comprises displacement sensing means for sensing relative displacement of the optical head with respect to the photosensitive medium, and the exposure timing of the optical head is synchronized with the output of the displacement sensing means.
REFERENCES:
patent: 4757327 (1988-07-01), Henzi
patent: 5105281 (1992-04-01), Kusaka
patent: 5371531 (1994-12-01), Rezanka et al.
patent: 59-9837 (1984-01-01), None
patent: 1-221271 (1989-09-01), None
patent: 2-169270 (1990-06-01), None
patent: 2-287527 (1990-11-01), None
patent: 3-230972 (1991-10-01), None
patent: 5-242614 (1993-09-01), None
patent: 6-316109 (1994-11-01), None
patent: 7-43669 (1995-02-01), None
patent: 7-311495 (1995-11-01), None
patent: 8-201930 (1996-08-01), None
Aizawa Chikara
Futakami Sigeru
Masubuchi Sadao
Matsunaga Masaaki
Nonaka Shin-ichi
Citizen Watch Co. Ltd.
Le N.
Nguyen Lamson D.
Smith , Gambrell & Russell, LLP
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