Stock material or miscellaneous articles – Two dimensionally sectional layer – Transparent or translucent layer or section
Reexamination Certificate
2001-01-31
2002-11-12
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Two dimensionally sectional layer
Transparent or translucent layer or section
C428S041700, C428S041800, C428S195100, C156S277000, C156S272800, C250S365000, C356S399000
Reexamination Certificate
active
06479120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a repair of a pattern defect of a base that is obtained by a technique of screen printing, e.g., plasma display panels. More particularly, the invention relates to a repair of a pattern defect of a printed material layer, which is performed after forming a variety of material layers, such as a dielectric layer and an electrode layer, on a substrate by a technique of screen printing.
2. Description of the Background Art
Screen printing (which is also called thick film printing) is a printing method in which a screen plate is placed in close proximity to a base and a pasty printing material is transferred from a screen mesh of a desired pattern to the base. This printing method is employed in forming a pattern of an electrode wire layer, a dielectric layer, a barrier rib portion, a phosphor layer or the like, on a substrate constituting a plasma display panel (PDP). Alternatively, this method is employed in forming a phosphor layer of a CRT (cathode ray tube), an electrode layer, a dielectric layer or the like of a printer head substrate.
In screen printing, after a printing material paste is transferred onto a substrate, a firing or heating process is performed under conditions suitable for the printing material paste to evaporate unneeded ingredients in the paste, thereby forming an electrode wire layer, a dielectric layer and the like on the substrate.
Such a screen printing is favorable for reducing manufacturing cost because of its low device cost and running cost. However, its pattern transfer accuracy is not so high and it is susceptible to a pattern defect Various improvements have been achieved to improve the transfer accuracy. However, for example, when a pattern of an electrode wire of a PDP is formed on a substrate (i.e., a base
35
) by printing as shown in
FIG. 7
, defects might occur at several points in the overall electrode wire of the substrate. For the panel of a display device, such as a PDP, a printed pattern defect directly deteriorates the display quality of the display device. Therefore, if a printed defect occurs, it is necessary to repair the defect.
In conventional repair of printed pattern defects, a pattern defect is found by observation with a microscope or the naked eye, and then a repair material paste
37
having the same composition as the printing material of a material layer is printed to a defect position by using a repair screen
36
as a screen plate for repair, as shown in
FIG. 8. A
repair pattern
38
having a width identical to the pattern width of a material layer repaired, as shown in
FIG. 9
, has been formed in the repair screen
36
. A repair printing is performed by squeezing the repair material paste
37
from the repair pattern
38
to a defective portion by using a squeegee
39
. Thereafter, in order to fire the repair material paste
37
of the defective portion, the substrate is put into a firing furnace as shown in
FIG. 10
, having a construction similar to that in firing printed patterns, and then subjected to a re-firing for the entire surface of the substrate.
The conventional pattern defect repairs by means of printing, however, have difficulties in alignment between the repair screen
36
and a pattern defect. Specifically, a screen printing causes a mismatch of patterns between a screen pattern and a pattern of paste that has actually been printed on a base. Therefore, such a mismatch must be taken into consideration when making an alignment between a screen plate and a pattern defect. Also, a pattern to be printed may actually vary with the kind of screen pattern and printing paste used and situations where a printing is performed. Thus, the pattern defect repair by printing requires much time to adjust an alignment, resulting in a poor working efficiency.
In addition, since a repair screen
36
on which a material paste for repair has been put is placed on a substrate, the surface of the substrate might become dirty.
Moreover, due to the characteristics of screen printing, it is difficult to transfer a material paste for repair into a local defective portion so as to have a uniform thickness, and a variation is liable to occur. Further, a repaired portion tends to upheave, which might adversely affect the smoothness and the like of other material layers that are formed thereon after repair.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, a defect repair sheet of a printed pattern used in repairing a pattern defect of a material layer that is printed on a base by employing a screen plate includes a transparent sheet; a material layer for repair formed on the transparent sheet; and an adhesive layer formed on the transparent sheet so as to cover the material layer for repair, having an adhesive property to the base which makes it possible to transfer the material layer for repair to the base.
According to a second aspect, the defect repair sheet of the first aspect is characterized in that the material layer for repair is formed on the transparent sheet so as to have a predetermined pattern
According to a third aspect, the defect repair sheet of the first aspect is characterized in that the adhesive layer includes a layer composed of a material that evaporates during a firing processing, which is performed after transferring the material layer for repair and the adhesive laver to a defective portion of the base.
According to a fourth aspect, the defect repair sheet of the third aspect is characterized in that the material layer for repair includes a layer composed of an electrode material.
According to a fifth aspect, a defect repair device for repairing a pattern defect of a material layer that is printed on a base by using a screen plate employs a defect repair sheet in which a material layer for repair having a predetermined pattern is formed on a transparent sheet, and includes an alignment means for aligning a pattern of the material layer for repair of the defect repair sheet and a pattern defective portion of the material layer of the base; and a transfer means for transferring the material layer for repair to the defective portion by pressing the defect repair sheet on the base from a side on which the material layer for repair is not formed, along a formed pattern of the material layer for repair.
According to a sixth aspect, the defect repair device of the fifth aspect is characterized in that the defect repair sheet further includes comprises an adhesive layer formed on the transparent sheet so as to cover the material layer for repair, having an adhesive property to the base which makes it possible to transfer the material layer for repair to the base.
According to a seventh aspect, the defect repair device of the sixth aspect is characterized in that the adhesive layer includes a layer composed of a material that evaporates during a firing processing, which is performed after transferring the material layer for repair and the adhesive layer to a defective portion of the base.
According to an eighth aspect, the defect repair device of the fifth aspect is characterized in that the alignment means includes an image taking means that takes an image of the base to obtain an image data of a pattern of the material layer; image processing means that detects a contour of a pattern of the material layer based on the image data and detects whether the pattern has a defect to output a result of image processing; and a position adjusting means that, when a defect is present in the pattern of the material layer, adjusts a position of the base so that the defective portion has a certain positional relation with respect to the material layer for repair of the defect repair sheet previously positioned in a predetermined position.
According to a ninth aspect, the defect repair device of the eight aspect is characterized in that the image taking means takes, before obtaining the image data, an image of the defect repair sheet from a side on which the material layer for repair is not formed, to obtain a p
Birch Stewart Kolasch & Birch
Dixon Merrick
Mitsubishi Denki & Kabushiki Kaisha
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