Photocopying – Projection printing and copying cameras – Image transferred to or from curved surface
Reexamination Certificate
2001-10-17
2003-07-08
Nguyen, Henry Hung (Department: 2851)
Photocopying
Projection printing and copying cameras
Image transferred to or from curved surface
C355S040000, C355S018000
Reexamination Certificate
active
06590632
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the technical field of an image recording method and an image recording apparatus, and more particularly, to an image recording system using a light modulator of two-dimensional arrangement (two-dimensional spatial light modulator) such as a micro mirror array or a two-dimensional mirror array device.
Mainly used in a digital image exposure system utilized in various types of printers is a so-called laser beam scan exposure (raster scan) for two-dimensionally exposing a recording medium with a laser beam modulated in accordance with an image to be recorded by deflecting the laser beam in a main scanning direction while relatively moving the recording medium and an optical system in an auxiliary scanning direction perpendicular to the main scanning direction.
In contrast, recently, various types of digital image exposure systems have been proposed which use two-dimensional spatial light modulators such as a liquid crystal display (hereinafter, referred to as “LCD”) and the micro mirror array (hereinafter, referred to as “MMA”) or the two-dimensional mirror array device (2DMAD) which is commercially available, for example, as a Digital Micromirror Device™ (DMD) manufactured by Texas Instruments Inc. that are utilized as display devices in displays, monitors and so on. In the exposure systems, a recording medium is basically exposed by forming an image displayed by the two-dimensional spatial light modulator on the recording medium.
In particular, the MMA is advantageous in exposure at high speed because the MMA has a modulation speed (response speed) faster than that of the LCD and moreover utilizes light more efficiently than the LCD.
Digital exposure systems using the spatial light modulator are disclosed in, for example, U.S. Pat. No. 5,049,901 and EP 0992350 A1.
The digital exposure systems disclosed in these publications each relate to an image recording apparatus in which an image is formed on a spatial light modulator such as the MMA in the form of an image signal and the image signal is imaged on a recording medium for recording. In the digital exposure systems, the image on the spatial light modulator is moved in synchronism with the movement of the recording medium which is moved in a main scanning direction so that the image can remain stationary on the recording medium. This operation enables image recording of high resolution by obtaining a small recording light spot from an extended light source which has difficulty in narrowing the area.
The principle of an image recording method using the conventional spatial light modulator will be described with reference to
FIGS. 3A
,
3
B and
3
C. As shown in
FIG. 3A
, light impinges on a spatial light modulator
90
and is reflected by a mirror
90
a
, and the reflected light is imaged onto a recording medium
94
through an optical system such as a lens
92
. It is assumed that the recording medium
94
moves at a constant speed as shown by an arrow in
FIGS. 3A
to
3
C. In
FIG. 3A
, only the mirror
90
a
is activated and mirrors
90
b
and
90
c
are deactivated, and only the light reflected by the mirror
90
a
is imaged onto the recording medium
94
.
Next, when the recording medium
94
slightly moves as shown in
FIG. 3B
, the mirror
90
a
in the spatial light modulator
90
is deactivated and only the mirror
90
b
is activated instead in synchronism with the movement of the recording medium
94
, and the same point on the recording medium
94
as shown in
FIG. 3A
is exposed to the light reflected by the mirror
90
b.
Further, when the recording medium
94
moves as shown in
FIG. 3C
, only the mirror
90
c
is activated in the spatial light modulator
90
in synchronism with the movement of the recording medium
94
and images at the same position on the recording medium
94
.
As described above, in the illustrated example, the spatial light modulator
90
changes image signaling three times so that each of the mirrors
90
a
,
90
b
and
90
c
exposes the recording medium
94
once, in total three times. As a result, the image is moved in synchronism with the movement of the recording medium
94
so as to remain stationary on the recording medium
94
.
As described above, however, when the image on the spatial light modulator is moved to cause the image to remain stationary on the recording medium, the image is moved with respect to the continuously moving recording medium by using the array-like discrete modulator such as the MMA. Thus, the image discontinuously moves on the modulator and is dragged by the pitch of one pixel on the recording medium. As a result, a problem arises in that an image larger than that of one pixel in the MMA is formed, which results in increase of the pixel size of the recorded image.
Further, another problem also arises in that a complicated signal processing circuit is necessary to move the image on the spatial light modulator so as to cause the image to remain stationary on the recording medium.
SUMMARY OF THE INVENTION
An object of the present invention, which was made in view of the above conventional problems, is to provide an image recording method which can overcome the problem of the increase in pixel size in image recording with a light modulator of two-dimensional arrangement and which enables image recording of high resolution using a large (broad) area light source without the need for a complicated signal processing circuit.
Another object of the present invention is to provide an image recording apparatus for implementing the image recording method as described above.
In order to attain the object described above, the first aspect of the present invention provides an image recording method in which a two-dimensional image formed by a group of two-dimensionally disposed light source elements is focused through an optical system on a recording medium which is moving in a relative relation to the group of two-dimensionally disposed light source elements, comprising the step of: deflecting light from the group of two-dimensionally disposed light source elements to move the image focused on the recording medium in synchronism with a movement of the recording medium such that the image can remain stationary at least in a main scanning direction in a relative relation to the recording medium.
Preferably, the group of two-dimensionally disposed light source elements is produced by a two-dimensional spatial light modulator illuminated with an illumination light flux.
In order to attain the object described above, the second aspect of the present invention provides an image recording apparatus, comprising: a group of two-dimensionally disposed light source elements; a recording medium which moves in a relative relation to the group of two-dimensionally disposed light source elements; and an optical system which focuses an image formed by the group of two-dimensionally disposed light source elements on the recording medium, wherein the optical system includes a light deflector for deflecting light from the group of two-dimensionally disposed light source elements, and the light deflector deflects the light to move the image focused on the recording medium in synchronism with a movement of the recording medium such that the image can remain stationary at least in a main scanning direction in a relative relation to the recording medium.
Preferably, the group of two-dimensionally disposed light source elements is produced by a two-dimensional spatial light modulator illuminated with an illumination light flux.
REFERENCES:
patent: 5049901 (1991-09-01), Gelbart
patent: 5978010 (1999-11-01), Hosokawa
patent: 6081316 (2000-06-01), Okamura et al.
patent: 6151099 (2000-11-01), Okamura et al.
patent: 6208369 (2001-03-01), Oren et al.
patent: 0992350 (2000-04-01), None
Fuji Photo Film Co. , Ltd.
Nguyen Henry Hung
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