Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
1999-09-13
2001-06-12
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S037000
Reexamination Certificate
active
06244702
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a technology for producing a color filter for a color liquid crystal display adapted for use in a color television, a personal computer or the like, and more particularly to a method and an apparatus for producing a color filter by arranging plural colored filter elements on an optically translucent substrate, the color filter, a liquid crystal display device and an apparatus having such liquid crystal display device.
Related Background Art
For producing the color filter, there are conventionally known the dyeing method, the pigment dispersion method, the electro-deposition method, the printing method etc.
The dyeing method prepares the color filter by forming a layer of a water-soluble polymer material, for dyeing, on a glass substrate, forming the above-mentioned material into a desired pattern by a photolithographic process, then immersing the glass substrate into a dyeing bath to obtain a colored pattern, and repeating this process three times for red, green and blue colors.
The pigment dispersion method prepares the color filter by forming a layer of photosensitive resin, in which pigment is dispersed, on a glass substrate, then patterning the resin layer to obtain a mono-colored pattern and repeating this process three times for red, green and blue colors.
The electrodeposition method prepares the color filter by forming a transparent electrode pattern on a glass substrate, then immersing the glass substrate in an electrodeposition liquid containing pigment, resin, electrolyte etc. for depositing a single color, and repeating this process three times for red, green and blue colors.
The printing method prepares the color filter by printing thermosetting resin, containing dispersed pigment, three times respectively for red, green and blue colors and then thermally setting the resin.
These four methods in common require repetition of a same process by three times for forming red, green and blue colors, and such large number of steps reduces the production yield and increases the cost.
Besides, the electrodeposition method is hardly applicable to the TFT liquid crystal display since the formable pattern is limited in shape. Also the printing method is limited in resolution and cannot therefore be applied to finer patterns.
In order to resolve these drawbacks, there is proposed a method of forming the filter pattern by ink jet emission onto the glass substrate, as disclosed in the Japanese Patent Laid-Open Application Nos. 59-75205, 63-235901, 1-217320 etc.
SUMMARY OF THE INVENTION
However, such technology utilizing ink jet has not yet been developed for the functions for production. More specifically, highly precise pattern formation is not possible because there has not been developed a system, for example, of measuring the reaching position of ink in advance, then aligning the glass substrate in directions of six freedoms with respect to the drawing head (or aligning the drawing head with respect to the glass) in mounting the glass substrate on the manufacturing apparatus, and maintaining a constant gap between the drawing head and the glass substrate in pattern drawing. Also no consideration has been given on the productivity.
An object of the present invention is to resolve such drawbacks and to provide a method and an apparatus for producing the color filter, which are inexpensive and highly reliable, and are capable of satisfying the characteristics of the conventional methods, such as resolution, exploiting the feature of the ink jet method.
More specifically it is to enable highly precise drawing of each color pattern of red, green and blue colors on the substrate with measures for avoiding dusts and improving the productivity, and also to enable flexible adaptation for example to a change in the size of the substrate.
Another object of the present invention is to provide a color filter produced by the above-mentioned method or apparatus, a liquid crystal display device and an apparatus equipped with such liquid crystal display device.
The above-mentioned objects can be attained, according to the present invention, by an apparatus for producing a color filter comprising at least a set of drawing heads for respectively generating ink jets of red, green and blue colors, movement means for moving with a substrate on which the color filter is to be formed by drawing with ink jets, displacement detection means for detecting relative displacement between the substrate and the drawing heads, means for detecting the reaching position, on the substrate, of the ink jet discharged from the drawing head, and alignment means for effecting alignment between the substrate and the drawing head, based on the result of detection of the reaching position and that of the relative displacement.
It is also featured by facts that the drawing heads are fixed above the substrate and that the alignment means and the movement means are both adapted to move the substrate in the alignment and in the drawing operation.
It is further featured by a fact that, for each drawing head, its reaching position is detected in advance for a surface in a predetermined positional relationship thereto.
It is further featured by a fact that the length of the drawing heads of red, green and blue colors is equal to the width of the substrate in the drawing direction.
It is further featured by a fact that plural sets of drawing heads are arranged in parallel with an entire length equal to the width of the substrate in the drawing direction.
It is further featured by a facts that the drawing heads are adapted to independently generate ink jets of red, green and blue colors, that the movement means is adapted to move within a plane of a predetermined distance from the drawing heads and that the relative displacement and the alignment are achieved in the directions of six freedoms.
Also according to the present invention, there is provided a method for producing a color filter in the above-mentioned apparatus by drawing on the substrate with the drawing heads under the movement of the substrate, comprising steps of detecting the relative displacement between the substrate and the drawing heads by the displacement detection means, detecting the reaching position, on the substrate, of the ink jet discharged from the drawing head, and effecting alignment between the substrate and the drawing head based on the result of detection of the reaching position and that of the relative displacement.
According to the present invention, in loading a substrate such as a glass substrate bearing a black matrix thereon on the movement means, there are detected the displacements in the X-direction (perpendicular to the head), the Y-direction (in the head scanning direction ) and the &thgr;-direction (rotation on the X-Y plane) by means of the displacement detection means for detecting the displacement of the alignment between the drawing head and the substrate, and the relative position between the head and the substrate is adjusted. The displacement is detected by detecting marks provided in two positions on the substrate with a microscope under the activation of the movement means, or by simultaneously detecting the marks on the substrate with two microscopes. The relative displacement, measured by the alignment microscope, is corrected by referring to the coordinate, measured in advance, between the reaching position of the ink discharged from the head and the alignment microscope (obtained for example by detecting the coordinates of the reaching position and the alignment position on the stage coordinate system). The drawing operation is conducted in reciprocating motions, with a constant gap control between the head and the substrate in the Z and tilt directions, under the measurement of the above-mentioned gap with a focusing sensor (or after only one measurement depending upon the accuracy).
In this manner, highly precise high-speed drawing can be achieved as the reaching position of ink is measured in advance. Also the relative position betwee
Masuda Kazuaki
Sakai Toshikazu
Sakino Shigeo
Tsuruoka Shinsuke
Barlow John
Canon Kabushiki Kaishi
Fitzpatrick ,Cella, Harper & Scinto
Stephens J.
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