Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-12-16
2003-04-22
Dudek, James (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S122000
Reexamination Certificate
active
06552771
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a non-light emitting or light emitting type image display device, and more particularly to an image display device, a correcting method and a correcting apparatus in which scratches on a panel glass surface in an image display section are repaired, and which are useful particularly in a thin film transistor-liquid crystal display (hereinafter abbreviated as TFT-LCD) or a plasma display panel (hereinafter abbreviated as PDP).
FIG. 1
is a schematic view showing the sectional structure of a well known TFT-LCD as a typical example of the prior art. The drawing shows three scratches
113
formed by mistake on the surface of a glass panel
106
in a display section. The scratches
113
are often observed when a manufacture apparatus contacts the glass surface in the manufacture process. Furthermore, the scratches
113
are formed particularly at locations where a glass substrate is held on a vacuum suction stage, and frequently generated by foreign matters caught between the substrate and the stage.
Environment management is performed at the manufacture site so as to reduce as much foreign matters as possible in the process, but it is impossible to completely eliminate foreign matters, so that scratches
113
on the glass surface are generated in a statistical frequency. Moreover, it is impossible to check amounts of foreign matters generated every process, and actually in many cases the presence of the scratches
113
formed on the glass surface is found for the first time in the final manufacture process of liquid crystal display panels, i.e., in the lighting inspection and whole appearance inspection performed before a polarizer
111
is applied to a liquid crystal display panel. Furthermore, back light is scattered by portions of the scratches
113
, and the display quality in liquid crystal displays is frequently deteriorated to an extent which cannot be ignored.
Since such liquid crystal display panels have gone through many processes, their added value is high. Therefore, loss of resources involved in disposal of such liquid crystal display panels in this stage cannot be ignored even if such disposal is low in frequency. Therefore, from the standpoint of social request for the conservation of environment resources, it is desired to repair the glass surface scratches
113
by means of some measures.
To solve the above-described problem, the following prior art has been generally used. More specifically, when a scratch or scratches are found on a glass surface in a display section of a liquid crystal display, a method has been employed, in which abrasion of the scratch or scratches and a portion or portions around the scratch or scratches is performed until such scratch or scratches are eliminated. This method is effective for a relatively shallow scratch or scratches having a depth of several &mgr;m or less, but is not entitled to be practical because such abrasion takes much time in the case of repairing a deep scratch having a depth of more than 10 &mgr;m. Further, there is offered a problem that it is even difficult to repair a wide scratch as compared with the above-described scratch, for example, when a micro crack develops deeply.
On the other hand, a method of repairing that scratch which cannot be treated by way of abrasion is disclosed in Japanese Patent Unexamined Publication No. 150205/1993 or 118401/1994.
More specifically, the technique disclosed in the Japanese Patent Unexamined Publication No. 150205/1993 comprises a method of dripping a liquid organic resin having a refractive index equivalent to or on the same order of that of a material of a glass substrate onto a scratch of the display panel glass substrate with a dispenser, which mounts a needle at a tip end thereof, thermosetting the resin, abrading a surplus resin remained around the scratch with a grinder, and flatting the glass surface.
The prior art document, however, has no detailed explanation of configuration and size of the needle mounted to the tip end of the dispenser, and supply condition of the organic resin and so on, and in no way numerically describes a situation, in which the organic resin is filled inside the scratch when the repair has been completed. Therefore, a standard used in judging to what extent the scratch is repaired or whether or not the object is attained is very vague, and it is difficult to judge the effectiveness of this technique.
Moreover, like the above-described prior art, the technique described in the Japanese Patent Unexamined Publication No. 118401/1994 comprises a method of filling the scratch with a liquid organic resin having a refractive index equivalent to or on the same order of that of the panel glass material, and thermosetting the resin.
However, this technique in no way details concretely how to fill the organic resin. Furthermore, a configuration of a portion, for which the scratch is repaired, is in no way described quantitatively, and it cannot but be said that it is difficult to precisely judge the effectiveness of the technique.
SUMMARY OF THE INVENTION
The inventors of the present application actually filled an organic resin in a scratch formed on a glass surface of a liquid crystal display panel on the basis of the above-described prior art, and have found that there are involved the following many problems and that the object cannot easily be achieved.
First, with reference to
FIG. 2
, an explanation will be given to a method of filling a liquid organic resin into a portion with a glass scratch on a panel surface, thermosetting the resin, and shaving off a surplus resin. When it is taken into consideration that the smaller an amount of the surplus resin, the easier the disposal thereof in the event of removing the surplus resin by means of some measures, it is desirable to supply an optimum amount of the resin, conformed to a volume of the scratch as far as possible, only into the scratch. A glass scratch
202
is various in size depending upon a size of a foreign matter responsible for the scratch such that various scratches are generated including a small scratch of about 50 &mgr;m and a large scratch exceeding 500 &mgr;m. Furthermore, the scratch
202
has a depth in the range of several &mgr;m to several tens of &mgr;m, and is also various in configuration.
Here, exemplifying a rectangular parallelepiped groove of 50 &mgr;m in width, 100 &mgr;m in length, and 5 &mgr;m in depth for the typical size of the glass scratch
202
as shown in
FIG. 2A
, this scratch is of 25000 &mgr;m
3
in volume. To precisely supply a minimum amount of resin (amounting to the volume of the scratch) into this scratch, it is essential to employ an injecting method in which an amount of the resin discharged at a time is made exceedingly small and is controllable. Concretely, it is required for the method to control the amount of the resin discharged at a time to at least 1000 to 5000 &mgr;m
3
. Therefore, the filling of the resin into the scratch is implemented by repeating the above-described high precision discharging, and a tool capable of discharging a small amount of liquid drop is necessary in order to fill the scratch with the minimum amount of the resin.
Here, an experiment has been conducted using a micro-syringe of the smallest volume (volume of 10 &mgr;L) among commercially available micro-syringes (small-sized syringes) for gas chromatography. Incidentally, this micro-syringe had a minimum graduation of 1 &mgr;L and a volume corresponding to that of a rectangular parallelepiped (10
9
&mgr;m
3
)with each side of 1 mm, the volume being extremely great as much as 4×10
4
times the volume of the above-described scratch of the typical size. More specifically, it is not possible with conventional syringes or dispensers to perform an operation of pouring the resin only into the area of the scratch
202
on a glass substrate
201
. Actually, if the above-described micro-syringe is used to fill a liquid epoxy resin or the like into the scratch and the resin is then thermoset, as shown in
FIG. 2B
Aiuchi Susumu
Asano Toshio
Inoue Takashi
Maruyama Shigenobu
Sawaguchi Takeo
Antonelli Terry Stout & Kraus LLP
Dudek James
Hitachi , Ltd.
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