Coating processes – Nonuniform coating – Applying superposed diverse coatings or coating a coated base
Reexamination Certificate
2001-11-20
2003-12-09
Parker, Fred J. (Department: 1762)
Coating processes
Nonuniform coating
Applying superposed diverse coatings or coating a coated base
C427S287000, C427S164000, C427S165000, C427S466000
Reexamination Certificate
active
06660332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a method and an apparatus for making a color filter used in an optical device, such as a liquid crystal display. The present invention also relates to a method and an apparatus for making a liquid crystal display having a color filter. Furthermore, the present invention relates to a method and an apparatus for making an electro-luminescent (EL) device for display using an electro-luminescent layer.
Also, the present invention relates to a method for discharging a material, and an apparatus for discharging thereof. Further, the present invention relates to electronic apparatus with a liquid crystal display device or an electro-luminescent device manufactured by the methods.
2. Description of Related Art
Currently, display devices, such as liquid crystal devices and EL devices, are increasingly used in the display sections of electronic devices, such as cellular phones and portable computers. Also recently, an increasing number of display devices are employing a full-color display. Full-color display in the liquid crystal devices is, for example, achieved by leading the light modulated by liquid crystal layers to pass through color filters. The color filters are formed by, for example, aligning dots of filter elements of red (R), green (G), and blue (B) in a predetermined configuration, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like.
In order to achieve full-color display in an EL device, dots of red (R), green (G), and blue (B) electro-luminescent layers (EL layers) are aligned in a predetermined pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like. Each of the EL layers is then sandwiched by a pair of electrodes so as to form a pixel, and the voltage applied to these electrodes is controlled according to the individual pixels so as to make the pixels emit desired colors and to achieve full-color display.
Conventionally, patterning of the R, G, and B filter elements and patterning of the R, G, and B pixels of the electro-luminescent device have been performed by photolithography. However, photolithography is a complex and costly process because the process consumes a large amount of colored materials, photoresists, and the like.
In order to overcome these problems, the use of an inkjet method in which the filter element and electro-luminescent layers aligned in the dot-matrix are formed by discharging in a dot-matrix a filter material, an electro-luminescent material, or the like, has been suggested.
Referring to
FIGS. 22A and 22B
, a plurality of filter elements
303
arranged in a dot matrix are formed by means of an inkjet method in the inner regions of a plurality of panel regions
302
defined on the surface of a mother substrate
301
, i.e., a large-size substrate made of glass, plastic, or the like.
Here, as shown in
FIG. 22C
, an inkjet head
306
having a nozzle line
305
including a plurality of nozzles
304
arranged in a row performs first-scanning a number of times (two times in
FIG. 22B
) relative to one panel region
302
as shown by arrows A
1
and A
2
in FIG.
22
B. Meanwhile, during the first-scanning, ink, that is, a filter material, is selectively discharged from the plurality of nozzles
304
so as to form filter elements
303
at the desired positions.
The filter elements
303
are formed by arranging colors such as R, G, and B, in an appropriate pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern. The process of discharging ink using the inkjet head
306
shown in
FIG. 22B
is performed as follows: three of the inkjet heads
306
, each of which discharges one of three colors from among R, G, and B, are prepared in advance; and these inkjet heads
306
are used sequentially to form a pattern of three colors, such as R, G, and B, on one mother substrate
301
.
As for the inkjet head
306
, generally, there is a variation between the amounts of ink discharged from the plurality of nozzles
304
constituting the nozzle line
305
. Accordingly, the inkjet head
306
has an ink-discharge characteristic Q shown in
FIG. 23A
, for example, wherein the discharge amount is largest at the positions corresponding to both ends of the nozzle line
305
, next largest at the position corresponding to the middle thereof, and least at the other positions.
Thus, when the filter elements
303
are formed using the inkjet head
306
as shown in
FIG. 22B
, dense lines are formed at positions P
1
corresponding to the end portions of the inkjet head
306
and/or at positions P
2
corresponding to the middle of the nozzle line, as shown in
FIG. 23B
, impairing uniformity of the in-plane light transmission characteristics of the color filter.
SUMMARY OF THE INVENTION
Accordingly, it is a feature of the present invention to provide a method and an apparatus for manufacturing an optical component which can make uniform the planar optical characteristics of the optical component, i.e., the light transmission characteristics of a color filter, the color display characteristics of a liquid crystal device, the light-emission characteristics of an electro-luminescent surface.
In achieving these features, the present invention provides a method for making a color filter with a plurality of filter elements aligned on a substrate. The method can include a step of moving one of a inkjet head and the substrate in a first-scanning direction relative to the other, wherein the inkjet head has a nozzle line including a plurality of nozzle groups each including a plurality of nozzles, a step of selectively discharging a filter material from the plurality of nozzles to form the plurality of filter elements, and a step of moving one of the inkjet head and the substrate in a second-scanning direction relative to the other so that at least a part of each nozzle group is capable of scanning the same section of the substrate in the first direction.
In accordance with the above-described method for making the color filter, each of the filter elements in the color filter is not formed by one first-scanning of the inkjet head, but instead each of the filter elements is formed into a predetermined thickness by being applied with ink n times from the plurality of nozzles belonging to different nozzle groups. Accordingly, even when there is a variation between the discharged amounts of ink among the plurality of nozzles, variations in the layer thickness among the plurality of filter elements can be avoided, and light transmission characteristics of the color filter can thereby be made uniform.
It is apparent that because the filter elements are formed by discharging ink from the inkjet head in the above-described method, complex processes such as those employing photolithography techniques are not required and the raw materials are efficiently consumed.
In the above-described method for making a color filter, one of the inkjet head and the substrate is moved relative to the other by a distance corresponding to an integral multiple of the length of one of the nozzle groups in the second-scanning direction.
In the above-described method for making a color filter, the nozzle line may be tilted relative to the second-scanning direction. The nozzle line is formed by arranging the plurality of nozzles in a line. When the nozzle line is arranged in a direction parallel to the second-scanning direction of the inkjet head, the distance between adjacent filter elements formed by the filter element material discharged from the nozzles, i.e., the element pitch, becomes equal to the distance between the adjacent nozzles constituting the nozzle line, i.e., the nozzle pitch.
If an element pitch equal to the nozzle pitch is desirable, the nozzle line need not be tilted, however such a case is rare. In most cases, the element pitch and the nozzle pitch are different. When the nozzle line is tilted relative to the second-scanning direction
Aruga Hisashi
Katagami Satoru
Kawase Tomomi
Kiguchi Hiroshi
Shimizu Masaharu
Oliff & Berridg,e PLC
Parker Fred J.
Seiko Epson Corporation
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