Liquid crystal display element

A liquid crystal display element which comprises a pair of substrates facing each other forming a cell gap therebetween and a sealing paste for bonding the pair of substrates and defining the cell between the substrates. The sealing paste is arranged to have an opening at a side edge of the cell for forming an injection port for injecting a liquid crystal in the cell. The port is sealed after the liquid crystal is injected in the cell. The display element further comprises a sealing member inserted onto the side edge of the cell at the position of the injection port. A clogging paste for covering and sealing the injection port is held within said sealing member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a liquid crystal display element, more 
particularly, it relates to a liquid crystal display element which 
comprises a substrate made from a polymer film and has a liquid crystal 
injection port. The improvement of the present invention resides in that 
the injection port is reliably closed and sealed after the liquid crystal 
is injected in the element. 
2. Description of the Related Art 
These days, the liquid crystal display element is widely used in various 
fields including the field of personal computer wherein the element is 
used as the terminal display device for the computer. Therefore, the 
liquid crystal display element has to be usable on various different 
conditions wherein the element is used. Also, it is desirable that such a 
display element be realized at a low cost. 
When producing such a display element, whether the liquid crystal injection 
port is sealed certainly or not is very influential not only to the 
functional reliability of the display element but also to the producing 
cost thereof. 
The liquid crystal display element comprises a cell constituted by a pair 
of substrates facing each other forming a cell space therebetween and 
bonded together by an adhesive agent to seal the periphery of the 
substrates. The injection port is formed at a corner of one of the 
substrates. The liquid crystal is injected into the cell through the port. 
After that, the port is sealed by applying a sealing paste to the port. 
However, the port is formed in the cell area defined by the sealing frame 
surrounding the cell, which means that the space unusable for displaying 
is formed in the cell area resulting in that the element becomes bulky. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a liquid 
crystal display element in which the display area is effectively arranged 
and the injection port is rigidly and reliably sealed with a small amount 
of sealing paste by a simple process. 
The above mentioned object of the present invention can be achieved by a 
liquid crystal display element comprising: 
a pair of substrates facing each other forming a cell gap therebetween; 
a sealing paste for bonding the pair of substrates and defining the cell 
between the substrates, the sealing paste having an opening at an side 
edge of the cell for forming an injection port for injecting a liquid 
crystal in the cell which port is to be sealed after the liquid crystal is 
injected; 
a sealing member inserted onto the side edge of the cell at the position of 
the injection port; and 
a clogging paste for covering and sealing the injection port, the clogging 
paste being held within the sealing member. 
More precisely, in accordance with the present invention, the liquid 
crystal display element comprises a cell constituted from a pair of 
polymer film substrates facing each other forming a cell space 
therebetween and bonded together by a sealing paste, an injection port 
being formed at an end of the cell for injecting the liquid crystal into 
the cell, the port being sealed by a sealing paste after the liquid 
crystal is injected, wherein a sealing member carrying a sealing paste 
thereon is fixed to the cell end where the injection port is formed so as 
to seal the injection port. The sealing member has a substantially 
U-shaped section for holding the cell end. 
Also, the sealing member of the present invention desirably comprises a 
stopper for limiting the fixing depth of the sealing member engaging with 
the cell end. The fixing depth may be limited by arranging a protruding 
portion on one of the substrates at the cell end where the injection port 
is formed so that the sealing member is stopped by the protruding portion. 
Advantages of the structure in accordance with the present invention are 
that a predetermined amount of sealing paste is accurately applied to the 
injection port with the use of the sealing member, which makes it possible 
to reliably seal the port and avoid leakage of liquid crystal, and that it 
becomes easy to seal the injection port by applying the sealing paste to 
the port by using the sealing member carrying an appropriate amount of the 
sealing paste. 
Further objects and advantages of the present invention will be apparent 
from the following discription of the preferred embodiments of the 
invention as illustrated in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Embodiments of the present invention are described hereinafter with 
reference to the drawings and in comparison to the related art structures 
which are also illustrated in the drawings. 
FIG. 1 illustrates a plan view of a liquid crystal display element cell 
having an injection port at a side edge thereof. 
The element comprises a cell 14 constituted from a pair of substrate 11 and 
12 which are bonded together by a sealing paste 13 forming a cell space 
therebetween. The central portion of the right side of the sealing paste 
13 is opened. The ends 13a and 13b of the sealing paste 13 at the opening 
portion are guided outward to the edges of the substrates 11, 12 so that 
an injection port 15 is formed at the cell edge. 
Such an injection port 15 is sealed after a liquid crystal is injected in 
the cell. 
FIG. 2 illustrates an example of the sealing structure of the injection 
port. The injection port 15 is sealed by a clogging paste 16. Each of the 
substrates 11 and 12 is made from a polymer film of about 100 .mu.m thick. 
Therefore, the thickness of the cell 14 is only slightly more than about 
200 .mu.m at best. Accordingly, if the clogging paste 16 is applied only 
to the side edge surface of the cell, a sufficient amount of the paste can 
not be supplied since the space of the side edge surface is very narrow. 
FIG. 3 illustrates a state of sealing structure wherein the clogging paste 
is applied only to the side edge surface of the cell as mentioned above. 
Since the amount of the clogging paste 16 is not enought to seal the port 
15 and a part of the paste 16 intrudes into the port 15 due to the 
capillary attraction, the port 15 is not reliably sealed so that the 
liquid crystal may leak through the port. 
FIG. 4 illustrates another state of the sealing structure wherein a large 
amount of the clogging paste 16 is applied to the injection port 15. In 
this case, however, the paste 16 is divided by the function of surface 
tension as illustrated in FIG. 5. Therefore, the amount of the paste 16 
covering the side surface is reduced so that the same problem as the state 
of FIG. 3 arises. 
As mentioned above, it is hard to reliably seal the injection port 15 
formed in the side edge of the cell. Besides, when the paste is hardened 
in the state that the paste is attached not only to the side surface of 
the cell but also to the upper and lower surfaces of the cell, the 
treatment of the cell becomes inconvenient. 
The embodiments of the present invention described below are improved from 
the above mentioned related art structure and obviate the problems of the 
related art mentioned above. 
FIG. 6 illustrates an example of the liquid crystal injection port formed 
in the side surface of the cell edge in accordance with the present 
invention. 
In the structure of FIG. 6, the cell 4 is constituted from a first 
substrate 1 and a second substrate 2 each of which substrates is made from 
a uniaxially extensible polyethylene terephthalate film of 100 .mu.m thick. 
ITO electrodes (not shown) are formed on each of the inside counter 
surfaces of the substrates 1 and 2. The ITO electrodes are covered by an 
orientation film which is treated by a rubbing operation. 
The cell 4 is produced by such a way that, first, gapping particles such as 
plastic beads are dispersed on the inside surface of one of the substrates 
1 and 2 and that a sealing paste 3 is applied on the periphery portion of 
the other substrate by, for example, a screen printing process and after 
that the two substrates are faced and bonded together by hardening the 
sealing paste 3. 
An injection port 5 is formed at a side edge of the cell 4 for injecting 
liquid crystal in the cell 4. The injection port 5 is defined by two ends 
of the sealing paste 3a and 3b which extend outward to the edge of the 
cell 4 so that the port opening is formed in the side surface at the edge 
of the cell. 
FIG. 7 illustrates another example of the injection port arrangement in 
accordance with the present invention. 
In this example, an opening 5 is formed in a side line of the sealing paste 
3 which is arranged in parallel with the edge of each substrate. A cut out 
1a is formed in one of the substrates at the position of the opening 5. 
Due to the cut 1a, a sufficient amount of clogging paste can be applied to 
the injection port 5 so that the port 5 can be reliably sealed after 
injecting the liquid crystal through the port 5. 
It is to be noted that the cut out may be formed in the substrate of the 
arrangement of FIG. 6 at the position of the port 5 between the seal ends 
3a and 3b. 
The above mentioned injection port (opening) 5 formed at an edge of the 
cell is sealed by a sealing paste with the use of a sealing member in 
accordance with the present invention after a liquid crystal is injected 
in the cell. 
FIGS. 8, 9 and 10 illustrate examples of the sealing member of the present 
invention. The sealing member is made from the same polymer film material 
as the substrate and has a substantially U-shaped section to hold the cell 
edge therebetween. 
FIG. 8 illustrates sealing member 7 constituted from a back portion 7a 
having a height corresponding to the sum of the substrates 1 and 2 and the 
sealing paste 3 (cell gap) and parallel holding pieces (7b and 7c cranked 
from the both edges of the back portion 7a. 
A predetermined amount of the clogging paste 6 (FIG. 11) is filled in the 
member 7. The member 7 is pushed and applied to the cell edge at the 
position of the injection port 5 so that the upper and lower pieces 7b and 
7c hold the cell. 
When the member 7 is pushed by a predetermined length onto the cell edge, 
the clogging paste 6 within the member 7 evenly covers the port 5 formed 
in the side surface of the cell edge. By hardening the clogging paste 6, 
the port 5 formed between the substrates 1 and 2 is covered by the 
hardened paste 6 and further by the member 7, which reliably seals the 
port 5 without occurrence of leakage of the liquid crystal through the 
port 5. 
FIG. 9 illustrates another example of the sealing member of the present 
invention. The sealing member 8 of FIG. 9 is constituted from a back 
portion 8a having a height corresponding to the sum of the substrates 1 
and 2 and the sealing paste 3 (cell gap) and a pair of holding pieces 8b 
and 8c each extending inward from the edge of the back portion 8a. Due to 
such a structure, the paste 6 is sufficiently applied to the side surface 
of the cell edge to seal the opening 5 and the edges of the pieces 8b and 
8c resiliently come in contact with the substrates 1 and 2 to tightly hold 
the cell edge. 
In accordance with the structure of the member 8 of FIG. 9, in addition to 
the advantages of the structure of FIG. 8, it becomes possible to reliably 
hold the member 8 at the position when the paste 6 is not yet hardened, 
which facilitates the sealing operation. 
FIG. 10 illustrates a still further example of the sealing member of the 
present invention. The sealing member 9 of FIG. 10 is constituted from a 
back portion 9a and holding pieces 9b and 9c as the structure of FIG. 9. 
Each holding piece 9b, 9c has an outwardly opening lip 9b.sub.1, 9c.sub.1 
formed at an edge thereof so as facilitate the insertion of the member 9 
onto the cell edge. 
Due to the arrangement of such lips of the holding members 9b and 9c, it 
becomes possible to easily insert the member 9 onto the cell edge (FIG. 
13). 
FIGS. 11, 12 and 13 illustrate the states wherein the port 5 formed at the 
cell edge is sealed by the sealing members 7, 8 and 9, respectively. 
FIGS. 14, 15 and 16 illustrate examples of the sealing member having a stop 
means for limiting the insertion length of the sealing member onto the cell 
edge. 
The sealing member 10 of FIG. 14 is constituted from a back portion 10a and 
holding pieces 10b and 10c cranked from the both edges of the back portion 
10a, respectively. The upper piece 10b is formed wider than the lower 
piece 10c so that stop tongues 10d and 10e are formed in the neck portion 
of the piece 10b. 
FIG. 17 illustrates the state wherein the member 10 of FIG. 14 is applied 
to the cell edge. The member 10 containing the clogging paste 6 therein is 
inserted onto the cell edge where the injection port is opening in the side 
surface of the edge. The insertion depth of the member 10 is limited by the 
stop tongues 10d and 10e which abut against the ends of the substrates 1 
and 2 so that a predetermined amount of paste 6 is held in the neck 
portion of the member 10 covering the port of the cell. Such an 
arrangement makes it possible to easily and accurately apply a 
predetermined amount of paste to the port opening and arrange the member 
at a predetermined position to avoid positional difference of the member 
between the products. 
FIG. 15 illustrates a still further example of the sealing member of the 
present invention. The sealing member of FIG. 15 is opened at the portion 
corresponding to the back portion 10a of the structure of FIG. 14. 
Instead, the upper and lower holding pieces 11b and 11c are connected by 
stop shoulders 11d and 11e. 
FIG. 16 illustrates a still further example of the sealing member of the 
present invention. The sealing member of FIG. 16 is different from the 
structure of FIG. 14 in that the upper and lower holding pieces 12b and 
12c are waved so as to tightly and reliably hold the cell edge, which 
facilitates the sealing operation. Other structure, function and 
advantages of the sealing member of FIG. 16 are substantially the same as 
those of FIG. 14. 
FIG. 18 illustrates a still further example of the sealing structure having 
the stop means in accordance with the present invention. In the structure 
of FIG. 18, the lower substrate 2 has a protrusion 2a projecting outward 
at the position of the injection port opening. The width L of the 
protrusion 2a is about the same as that of the sealing member applied 
thereto. Due to this protrusion 2a, the sealing member is stopped at a 
predetermined position corresponding to the projecting length of the 
protrusion 2a to limit the insertion length of the member onto the cell 
edge. 
FIG. 20 illustrates the state wherein the sealing member 7 is applied to 
the cell edge of FIG. 18. The protrusion 2a abuts against the back portion 
7a of the sealing member so that the insertion length of the sealing member 
7 is limited to remain a space in front of the port opening to hold a 
predetermined amount of clogging paste therein. 
FIG. 19 illustrates a still further example of the sealing structure having 
the stop means in accordance with the present invention. The structure of 
FIG. 19 has a protrusion 2a having guide pieces 2b at the both ends 
thereof. The length L between the guides 2b is slightly wider than the 
width of the sealing member to be applied thereto. Due to such an 
arrangement, the sealing member is accurately positioned between the 
guides 2b, which facilitates the sealing operation and raises the accuracy 
of the positioning of the sealing member. 
Many widely different embodiments of the present invention may be 
constructed without departing from the spirit and scope of the present 
invention. It should be understood that the present invention is not 
limited to the specific embodiments described in the specification, except 
as defined in the appended claims. 
An opening 5 may be disposed on corners of a side edge of a cell 14. In 
this case, the sealing member 7 with the clogging paste 6 is held on the 
corners.