Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-07-02
2004-07-06
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06758550
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a method and apparatus for manufacturing a color filter, a liquid-crystal display, an electroluminescence emission layer substrate, and an electroluminescence device. The present invention also relates to a scanning method and a scanning apparatus for a head that scans a substrate while ejecting a discharge material to the substrate. The present invention further relates to a method and apparatus for forming a film on a substrate. The present invention still further relates to an electrooptical device and a method for manufacturing the electrooptical device, and electronic equipment.
2. Description of Related Art
Currently, displays, such as a liquid-crystal display and an electroluminescence device, are widely used for electronic equipment, such as a mobile telephone or a mobile computer. The display of the electronic equipment typically presents a full-color display.
The full-color display of the liquid-crystal display is presented by transmitting light modulated by a liquid-crystal layer through a color filter. The color filter is formed by arranging R (red), G (green), and B (blue) color filter dot elements in a predetermined layout such as a stripe configuration, a delta configuration, or a mosaic configuration on the surface of a substrate fabricated of glass, plastic, etc.
In the electroluminescence device, an electroluminescence device can be formed by arranging R (red), G (green), and B (blue) color light emission layers in a predetermined layout, such as a stripe configuration, a delta configuration, or a mosaic configuration on the surface of a substrate fabricated of glass, plastic, etc. The light emission layer of the electroluminescence substrate is sandwiched between a pair of electrodes, forming a plurality of display dots. A current or voltage applied between the electrodes is controlled dot by dot to cause each display dot to emit light in a desired color.
When the filter elements of R (red), G (green), and B (blue) of the conventional color filter are patterned, or when the light emission layers of R (red), G (green), and B (blue) of the conventional electroluminescence substrate are patterned, the photolithographic technique has been used. The photolithographic technique performs complex steps, such as exposure, development, and cleaning steps using pattern masks different from display dot to display dot. A great deal of color material and photoresist are used, leading to costly units.
To resolve this problem, methods have been proposed in which a filter material or a light emission layer forming material is ejected in dots using an ink-jet technique to produce the filter element or the light emission layer. The ink-jet technique uses an ink-jet head with a piezoelectric thin film element, for example.
Through the ink-jet technique, ink for forming a pixel is stored in a pressure chamber of an ink-jet head, and is then ejected in response to a change in the volume of the pressure chamber due to the vibration of the piezoelectric element. A pixel is thus formed on the substrate of the color filter. The ink-jet technique heightens the production yield of the color filter. Furthermore, the ink-jet technique allows the amount of ink to be precisely controlled, thereby efficiently producing a high-resolution color filter.
FIG.
25
and
FIG. 26
illustrate methods for forming a filter element or a light emission layer in a dot-like configuration wherein a filter material and a light emission layer forming material is ejected using the ink-jet technique.
Referring to FIG.
25
(
a
), a plurality of panel regions
302
are formed on the surface of substrate (a mother substrate)
301
having a large area fabricated of glass or plastic. Referring to FIG.
25
(
b
), a plurality of filter elements
303
arranged in a dot-like configuration are formed in the internal area of each of the panel regions
302
. Referring to FIG.
25
(
c
), an ink-jet head
306
having a nozzle row
305
formed of a plurality of nozzles
304
are used to form the plurality of filter elements
303
through the ink-jet technique.
Referring to FIG.
25
(
b
), the ink-jet head
306
is moved in a main scan operation in directions designated by an arrow A
1
and an arrow A
2
, a plurality of times for a single panel region
302
, twice in FIG.
25
(
b
). During the main scan, the plurality of nozzles
304
selectively ejects ink, for example, a filter material, thereby forming a filter element
303
at a desired location.
The filter element
303
is formed by arranging R (red), G (green), and B (blue) colors in a stripe configuration, a delta configuration, a mosaic configuration, etc. When the filter element
303
is formed by the ink-jet head
306
shown in FIG.
25
(
b
), three types of ink-jet heads
306
respectively ejecting the inks of the three colors of R (red), G (green), and B (blue) are prepared. The ink-jet heads
306
are then successively used for the three colors, thereby arranging the three colors of R (red), G (green), and B (blue) on a single mother substrate
301
.
SUMMARY OF THE INVENTION
The plurality of nozzles
304
forming a nozzle row
305
in the ink-jet head
306
suffers from variations in the amount of ejected ink. For example, the ink-jet head
306
has ink discharge characteristics Q as shown in FIG.
26
(
a
), specifically, the amount of ejected ink is largest at the both ends of the nozzle row
305
, next largest in the center of the nozzle row
305
, and smallest in the middle between the end and the center of the nozzle row
305
. The number of nozzles
304
is 180 in FIG.
26
(
a
).
When the ink-jet head
306
produces the filter elements
303
as illustrated in FIG.
25
(
b
), dense streaks are formed in a formation area P
1
of the filter elements
303
corresponding to both ends of the ink-jet head
306
, and in a formation area P
2
of the filter elements
303
corresponding to the center of the ink-jet head
306
, because of variations in the amount of ejected ink. Thus, planar light transmissivity or light reflectivity of the color filter suffers from non-uniformity. There are times when very dense streaks appear in both the formation area P
1
and the formation area P
2
.
When the color filter is produced through such an ink-jet method, the ink-jet head needs to be precisely moved so that the nozzle of the ink-jet head precisely scans the region of a pixel, namely, of a display dot and then ejects ink at an appropriate position. There are still no satisfactory solutions available to this problem.
This problem is specifically discussed. Ink is ejected during the formation of the filter element or the light emission layer, namely, during the formation of the pixel. Color mixing could happen if ink to be deposited on one pixel formation region leaks into another adjacent pixel formation region. To prevent such color mixing, the nozzle must pass right above the pixel formation region, thereby depositing an ink drop to the center of the pixel as close as possible. If the nozzle is not positioned right above the pixel formation region, the nozzle must not eject ink.
Besides such a problem, the spacing of pixels (namely, a filter element pitch or a pixel pitch) in the head line-feed direction (namely, a sub scan direction) never agrees with the spacing of nozzles (namely, a nozzle pitch) in the sub scan direction. If the ink-jet head is simply moved in a main scan operation, the ink-jet head has some nozzles unable to pass right above the pixel formation region, namely, some nozzles that must not be used. The utilization of the nozzles (namely, the printing efficiency of the nozzles) thus drops. Conventional solution to this problem is not satisfactory enough.
The present invention has been developed in view of the problem, and it is an object of the present invention to increase the utilization of nozzles (the printing efficiency of the nozzles) by causing all nozzles of an ink-jet head to precisely pass right over pixel formation regions during the scan of an ink-jet head whe
Aruga Hisashi
Ito Tatsuya
Katagami Satoru
Kawase Tomomi
Gordon Raquel Yvette
Oliff & Berridg,e PLC
Seiko Epson Corporation
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