Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
1998-07-28
2002-05-14
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
Reexamination Certificate
active
06386700
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a color-filter manufacturing method for manufacturing a color filter by forming a colored layer with the use of an ink-jet head, a color filter manufactured by the manufacturing method, a display device including the color filter, and an apparatus having the display device.
With recent advances in personal computers, especially portable personal computers, the demand for liquid crystal displays has risen, especially color liquid crystal displays. However, in order to further popularize the use of liquid crystal displays, a reduction of cost must be achieved. Especially, it is required to reduce the cost of a color filter which constitutes a large proportion of the total cost. Various methods have been tried to satisfy the required characteristics of color filters while meeting the above requirements. However, no method capable of satisfying all the requirements has been established. The respective methods will be described below.
The first method is a pigment dispersion method. In this method, a pigment-dispersed photosensitive resin layer is formed on a substrate and patterned into a single-color pattern. This process is repeated three times to obtain R, G, and B color filter layers.
The second method is a dyeing method. In the dyeing method, a water-soluble polymer material as a dyeable material is applied onto a glass substrate, and the coating is patterned into a desired shape by a photolithographic process. The obtained pattern is dipped in a dye bath to obtain a colored pattern. This process is repeated three times to form R, G, and B color filter layers.
The third method is an electrodeposition method. In this method, a transparent electrode is patterned on a substrate, and the resultant structure is dipped in an electrodeposition coating fluid containing a pigment, a resin, an electrolyte, and the like to be colored in the first color by electrodeposition. This process is repeated three times to form R, G, and B color filter layers. Finally, these layers are calcined.
The fourth method is a print method. In this method, a pigment is dispersed in a thermosetting resin, a print operation is performed three times to form R, G, and B coatings separately, and the resins are thermoset, thereby forming colored layers. In all of the above methods, a protective layer is generally formed on the colored layers.
The point common to these methods is that the same process must be repeated three times to obtain layers colored in three colors, i.e., R, G, and B. This causes an increase in cost. In addition, as the number of processes increases, the yield decreases. In the electrodeposition method, limitations are imposed on pattern shapes which can be formed. For this reason, with the existing techniques, it is difficult to apply this method to TFTs. In the print method, a pattern with a fine pitch is difficult to form because of poor resolution and poor evenness.
In order to eliminate these drawbacks, methods of manufacturing color filters by an ink-jet system are disclosed in Japanese Patent Laid-Open Nos. 59-75205, 63-235901 and 1-217320. According to these methods, inks having three colors of pigment R (red), G (green) and B (blue) are discharged on a light-transmitting substrate by ink-jet method and each ink is dried to form a colored image portion. Such ink-jet method enables forming of pixels colored in R, G and B, all at once. Therefore, the manufacturing process can be greatly simplified and large cost-down effect can be attained.
In the ink-jet printing method, an ink-jet head having a plurality of ink-discharge nozzles is scanned over a substrate, and performs coloring of a plurality of pixel columns arrayed in the direction orthogonal to the scanning direction. However, when there is fluctuation in the amount of ink discharged by each of the nozzles of the ink-jet head, a problem arises in that density unevenness occurs among pixel columns arrayed in the direction orthogonal to the scanning direction.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above problem, and the object of the present invention is to provide a color-filter manufacturing method which can greatly reduce density unevenness among pixels of a color filter.
Another object of the present invention is to provide a color filter manufactured by the above manufacturing method, a display device including the color filter, and an apparatus having the display device.
In order to solve the above-described problems and attain the above objects, the color-filter manufacturing method according to the first aspect of the present invention is a color-filter manufacturing method of coloring each pixel of a color-subject material by scanning an ink-jet head, having a plurality of ink-discharge nozzles in a direction substantially orthogonal to a scanning direction, with relative to the color-subject material, and discharging ink to the color-subject material by the plurality of ink-discharge nozzles, comprising the steps of: calculating a theoretical ink discharge pitch D for each of the ink-discharge nozzles in accordance with an amount of ink discharged per single discharge of each of the plurality of ink-discharge nozzles, in order to make an amount of ink discharged for each pixel constant; and discharging ink such that, assuming a minimum moving pitch of an amount of relative movement of the ink-jet head in the scanning direction is d, in a case where a value kD (k is an integer equal to or larger than 0) corresponding to a theoretical discharge position of an n-th ink dot discharged along the scanning direction coincides with nd (n is an integer equal to or larger than 0), ink is discharged at a position substantially satisfying kD=nd, and in a case where kD takes a value between nd and (n+1)d, ink is discharged at a position corresponding to nd or a position corresponding to (n+1)d.
Furthermore, a color filter according to the first aspect of the present invention is a color filter manufactured by coloring each pixel of a color-subject material by scanning an ink-jet head, having a plurality of ink-discharge nozzles in a direction substantially orthogonal to a scanning direction, with relative to the color-subject material, and discharging ink to the color-subject material by the plurality of ink-discharge nozzles, the color filter manufactured by the steps of: calculating a theoretical ink discharge pitch D for each of the ink-discharge nozzles in accordance with an amount of ink discharged per single discharge of each of the plurality of ink-discharge nozzles, in order to make an amount of ink discharged for each pixel constant; and discharging ink such that, assuming a minimum moving pitch of an amount of relative movement of the ink-jet head in the scanning direction is d, in a case where a value kD (k is an integer equal to or larger than 0) corresponding to a theoretical discharge position of an n-th ink dot discharged along the scanning direction coincides with nd (n is an integer equal to or larger than 0), ink is discharged at a position substantially satisfying kD=nd, and in a case where kD takes a value between nd and (n+1)d, ink is discharged at a position corresponding to nd or a position corresponding to (n+1)d.
Furthermore, a display apparatus according to the first aspect of the present invention is a display device including a color filter manufactured by coloring each pixel of a color-subject material by scanning an ink-jet head, having a plurality of ink-discharge nozzles in a direction substantially orthogonal to a scanning direction, with relative to the color-subject material, and discharging ink to the color-subject material by the plurality of ink-discharge nozzles, the display device integrally comprising: light-amount changing means for enabling to change an amount of light; and a color filter manufactured by the steps of: calculating a theoretical ink discharge pitch D for each of the ink-discharge nozzles in accordance with an amount of ink discharged pe
Barlow John
Brooke Michael S
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