Photocopying – Projection printing and copying cameras – Identifying – composing – or selecting
Reexamination Certificate
1999-12-09
2001-10-02
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Identifying, composing, or selecting
C355S035000, C355S018000, C355S040000
Reexamination Certificate
active
06297875
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photograph printing device which, by irradiating light emitted from a light source to a printing paper used as a photosensitive material through an image display device, such as a liquid crystal display, prints out an image displayed on the image display device onto the printing paper, and more particularly, to a photograph printing device which can print out a high-quality image by pixel displacement.
BACKGROUND OF THE INVENTION
Researches and development have been conducted actively with a photograph printing device which serves as a so-called digital exposure device employing an image display device, such as a liquid crystal display. The photograph printing device of this type controls passing of light emitted from a light source through each pixel in the liquid crystal display by driving each pixel in accordance with image information, and irradiates the light having passed through each pixel on a printing paper, thereby printing out an image corresponding to the image information onto the printing paper.
Incidentally, resolution of a printed out image by such a digital exposure device corresponds to the number of pixels in the liquid crystal device. In order to improve resolution, for example, only the number of pixels in the liquid crystal display has to be increased. In this case, however, the liquid crystal display as a whole is undesirably upsized because of the increased number of pixels.
In recent years, a technique so-called “pixel displacement” is generally used in improving resolution of the printed out image. The pixel displacement is a technique, in which either the liquid crystal display or the printing paper is displaced relatively with respect to the other by, for example, half the pixel, and exposure is effected in each displacement. Consequently, although the number of the pixels in the liquid crystal display remains the same, resolution can be improved as if the number of pixels in the liquid crystal display were increased. Therefore, in this case, image quality can be upgraded by a less expensive device of a smaller size. The following will describe a photograph printing device which can effect the pixel displacement.
As shown in FIG.
16
(
a
), the photograph printing device includes a lamp
51
serving as a light source, an image display device
52
composed of, for example, a liquid crystal display, a lens
53
, rotatable BGR filters
54
, and an XY stage
56
, which are sequentially positioned in this order along the direction of light emitted from the lamp
51
on an optic axis linking the lamp
51
and XY stage
56
. The XY stage
56
is furnished with a table, which has a main surface perpendicular with respect to the optic axis and is allowed to move in two directions perpendicular to each other within a single plane. According to the above arrangement, when a printing paper
55
is placed on the XY stage
56
, the printing paper
55
can be moved in either of the two directions perpendicular to each other in the same plane.
With the above arrangement, passing of light through each pixel in the image display device
52
is controlled by driving each pixel with an image signal. Thus, light emitted from the lamp
51
is modulated at each pixel in the image display device
52
to reach the lens
53
and then focused. Light having passed through the lens
53
is irradiated to the printing paper
55
through one of the BGR filters
54
, for example, the B (Blue) filter. When printing of a blue image is completed, the BGR filters
54
are rotated, and by sequentially setting the G (Green) filter and R (Red) filter at the position matching on the optic axis, a green image and a red image are printed out sequentially in the same manner as above, whereby a color image is printed out onto the printing paper
55
. FIG.
17
(
a
) shows pixels which form the color image printed out onto the printing paper
55
by the first exposure (exposure of each of BGR).
When the first print out of the color image is completed, the XY stage
56
is driven so as to displace the printing paper
55
in a horizontal direction by one pixel, for example. Then, the second print out of a color image is effected in the same manner as above. FIG.
17
(
b
) shows pixels which form the color image printed onto the printing paper
55
up to the second exposure.
Thereafter, the XY stage
56
is driven so as to displace the printing paper
55
in a vertical direction by one pixel, and the third print out of a color image is effected in the same manner as above. Finally, the printing paper
55
is displaced back in the horizontal direction by one pixel, and the fourth print out of a color image is effected in the same manner as above. FIGS.
17
(
c
) and
17
(
d
) show pixels which form the color images printed onto the printing paper
55
up to the third exposure and fourth exposure, respectively.
Each pixel in the image display device
52
is supplied with a different image signal as a driving signal in every exposure (print out) from first to fourth.
By effecting the pixel displacement in the above manner, resolution of the image printed out onto the printing paper
55
can be improved two times both in the horizontal and vertical directions, thereby making it possible to upgrade the quality of the image printed out onto the printing paper
55
.
The foregoing explained the arrangement, in which the image display device
52
was fixed and the printing paper
55
was displaced by one pixel with respect to the image display device
52
in each exposure. However, as shown in FIG.
16
(
b
), the printing paper
55
may be fixed, and the image display device
52
may be placed on the XY stage
56
so as to be allowed to move in two directions perpendicular to each other in a single plane perpendicular with respect to the optic axis, so as to displace the image display device
52
by one pixel with respect to the printing paper
55
. In this case, pixels as shown in FIGS.
17
(
a
) through
17
(
d
) can be obtained by the pixel displacement as well.
Incidentally, as shown in FIG.
16
(
a
), with the photograph printing device of the above arrangement, that is, of the type that displaces the printing paper
55
, there will be no problem when the printing paper
55
is a standard size paper (so-called sheet paper), such as a B5 or A4 (specified below) paper, and a postcard. However, in case that a paper roll made of a lengthy piece of paper with a particular width, namely, a roll of paper, is used as the printing paper
55
, it is very difficult to displace the printing paper
55
because of its length. For example, even if transportation mechanism and holding mechanism for a roll of paper are improved so as to realize the displacement thereof, the arrangements of the transportation mechanism and holding mechanism becomes so complicated that it is well predicted that the costs of the device itself will be increased.
If it is arranged in such a manner that the printing paper
55
is displaced only in the exposure section, the printing paper
55
is folded or wrinkled, thereby deteriorating the quality of the printing paper
55
. Moreover, if an image is printed out onto such a deteriorated printing paper
55
, the display quality and reliability of the image are reduced. For the reasons discussed above, it is preferable not to adopt this arrangement as much as possible.
Incidentally, the B5 and A4 are the size of papers defined by JIS (Japanese Industrial Standards). More specifically, B5 is a paper size of 182 mm×257 mm, and A4 is a paper size of 210 mm×297 mm.
On the other hand, according to the arrangement of the photograph printing device of the type which displaces the image display device
52
as shown in FIG.
16
(
b
), vibration of the XY stage
56
is conveyed to the image display device
52
each time the image display device
52
is displaced. As previously mentioned, the image display device
52
is composed of, for example, the liquid crystal display. However, the liquid crystal display includes many scanning li
Adams Russell
Conlin David G.
Dike, Bronstein, Roberts & Cushman IP Group, Edwards & Angell, L
Hartnell, III George W.
Nguyen Hung Henry
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