Abstract:
A novel liquid crystal display apparatus includes a substrate kit and an assembling member. The substrate kit includes first and second polymer substrates on which electrodes are mounted and which are deposited in parallel in a horizontal direction such that the electrodes face each other. A sealing member is deposited around a circumference of the first and second polymer substrates such that a sealed space is made by the electrodes and the sealing member. The first polymer substrate forms a substrate extension extending outwards in a horizontal plane and the electrode bonded on the first polymer substrate forms an electrode extension extending along the substrate extension. The substrate kit further includes liquid crystal sealed inside the sealed space, polarizing seals bonded on each of the pair of polymer substrates on sides opposite to the sides having the electrodes, and an assembling member on which the substrate kit is mounted. In such a liquid crystal display apparatus, at least a portion of the electrode extension is bent in a direction towards the second polymer substrate before the substrate kit is mounted on the assembling member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a liquid crystal display apparatus, and more particularly to a liquid crystal display apparatus which is capable of preventing a break due to a crack caused during a manufacturing process. 
     2. Discussion of the Background 
     A liquid crystal display apparatus, an important man-machine communications device, is used in a variety of electronic devices such as electronic watches, personal digital assistant (PDA) systems, word processors, copying machines, facsimile machines, and so on. In the liquid crystal display apparatus, a polymer substrate has been widely employed in place of a glass substrate. Utilizing a polymer substrate is a known technique and is described in, for example, Japanese Laid-Open Patent Application No. 07-043697 (1995) referring to an exemplary structure of a liquid crystal display apparatus shown in FIG.  1 . The liquid crystal display apparatus of FIG. 1 has a typical structure which includes a pair of polymer substrates  1  and  2 , indium-tin oxide (ITO) electrodes  3  and  4 , a sealing member  5 , a liquid crystal  6 , and polarizing seals  10  and  11 . The ITO electrodes  3  and  4  are bonded on the sides of the polymer substrates  1  and  2  to face each other. The sealing member  5  is deposited between the ITO electrode films  3  and  4  around the edge of the ITO electrode film  3  so that the liquid crystal  6  is sealed therein. In the liquid crystal display apparatus having the structure mentioned above, the liquid crystal  6  is energized to display information in a form of alphanumeric symbols, for example, by applying an electrical current to the ITO electrodes  3  and  4 . 
     In general, a liquid crystal display apparatus having the above-described structure is used as part of an electronic device (not shown), for example, and is therefore mounted inside a housing or the like of the electronic device. FIG. 1 shows a connecting portion of the electronic device and the liquid crystal display apparatus. The electronic device includes a connecting member  7 , a solder  8 , bumps  8   a , and an electrode  9 . The connecting member  7  is extended from a circuit substrate (not shown) or the like of the electronic device to supply power to the liquid crystal display apparatus. For this purpose, an extension  2   a  is extended from the polymer substrate  2  and an electrode extension  4   a  is extended from the ITO electrode  4  along the extension  2   a.    
     To electrically connect the electrode extension  4   a  to the connecting member  7 , the electrode extension  4   a  is typically pressed against the connecting member  7  and is then soldered with the solder  8 , which is deposited together with the bumps  8   a  between the electrode  9  bonded on the bottom of the connecting member  7  and the electrode extension  4   a.    
     However, the above-mentioned way of connecting the liquid crystal display apparatus to the electronic device provides a stress to the electrode extension  4   a  on the electrode  4  or to the electrode extension  4   a  at a position under the sealing member  5 , which may generate a crack  12 . This may eventually cause a failure of electrical connection between the liquid crystal display apparatus and the circuit substrate of the electronic device. As a result, the liquid crystal cannot properly display information. This kind of error may be caused not only when the electrode extension  4   a  is connected to the connecting member  7  using heat and pressure, but also when the electrode extension  4   a  receives an excessive stress during the installation of the liquid crystal display to the electronic device. 
     One technique for preventing this problem is to extend the polarizing seal  11  to cover the length of the extension of the polymer substrate  2   a  so as to support the electrode extension  4   a . However, this technique is not sufficient because such a technique would be effective only after the extended polarizing seal  11  is attached and the electrode extension  4   a  may receive a stress and may be bent, as shown by dotted lines in FIG. 2, before the extended polarizing seal  11  is attached. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide a novel liquid crystal display apparatus which eliminates the unstable connection problems as discussed above. 
     To achieve this object and other objects, a novel liquid crystal display apparatus of the present invention includes a substrate kit and an assembling member. The substrate kit includes first and second polymer substrates, each of which has an electrode on an entire surface of one side thereof. The first and second polymer substrates are deposited in parallel in a horizontal direction such that the electrodes face each other, and have a sealing member deposited therebetween around a circumference thereof such that a sealed space is made by the electrodes and the sealing member. The first polymer substrate forms a substrate extension extending outwards in a horizontal plane and the electrode bonded on the first polymer substrate forms an electrode extension extending along the substrate extension. 
     The substrate kit further includes a liquid crystal which is sealed inside the sealed space, polarizing seals bonded on each of the pair of polymer substrates on a side opposite to the side having the electrode, and an assembling member on which the substrate kit is mounted. In such a liquid crystal display apparatus, at least a portion of the electrode extension is bent in a direction towards the second polymer substrate before the substrate kit is mounted on the assembling member. 
     The polarizing seal bonded on the first polymer substrate may be extended approximately to an end of the substrate extension. 
     The electrode extension may be bent at an angle from 2 degrees to 20 degrees, or with a radius of curvature in a range of 10 mm to 100 mm. 
     Further, the assembling member may include a supporting frame for supporting the apparatus. The supporting frame may have a surface contacting the second polymer substrate and a rise at one end which engages a rim of the electrode extension such that the electrode extension is bent in a direction towards the second polymer substrate. 
     Further, the assembling member may include a supporting frame for supporting the apparatus. The supporting frame may include a surface contacting the first polymer substrate and, at one end, a slope having an angle from 2 degrees to 20 degrees. In this case, the slope is used to bend the electrode extension in a direction towards the second polymer substrate. 
     Further, when the apparatus mounted on the assembling member is installed in a different housing, a part of the different housing may hold the assembling member so as to secure the electrode extension. 
     Other objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
     FIGS. 1 and 2 are illustrations for explaining a typical structure of a liquid crystal display of a backgound art; 
     FIG. 3 if an illustration for explaining an exemplary structure of a liquid crystal display apparatus having extensions of a substrate, electrode, and polarizing seal with a slope having a predetermined angle, according to an embodiment of the present invention; 
     FIG. 4 is an illustration for explaining an exemplary structure of a liquid crystal display apparatus having extensions of a substrate, electrode, and polarizing seal with a curve having a predetermined radius of curvature, according to an embodiment of the present invention; 
     FIGS. 5-7 illustrations each for explaining a way of mounting the liquid crystal display apparatus on an assembling frame; and 
     FIG. 8 is an illustration for explaining an exemplary structure in which the liquid crystal display apparatus according to the present invention and mounted on an assembling frame is installed inside a console panel of a copying machine. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the present invention is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents which operate in a similar manner. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 3 thereof, there is illustrated an exemplary structure of a liquid crystal display apparatus  34  according to an embodiment of the present invention. While FIG. 3 shows an edge portion of the liquid crystal display  34 , the entire apparatus has a box shape although it is not shown. 
     In FIG. 3, the liquid crystal display  34  includes a pair of polymer substrates  21  and  22 , ITO (indium-tin oxide) electrodes  23  and  24 , a sealing member  25 , a liquid crystal  26 , and a pair of polarizing seals  27  and  28 . The ITO electrodes  23  and  24  are bonded to the polymer substrates  21  and  22 , respectively, such that the ITO electrodes  23  and  24  face each other with a distance to form a space for holding the liquid crystal  26  therebetween. Both of the polymer substrates  21  and  22  have a side in the vertical direction of the drawing, along which the sealing member  25  is disposed so as to seal the liquid crystal  26  held in the space between the electrodes  23  and  24 . 
     When an electric current passes through the electrodes  23  and  24  configured in the above-mentioned way, the liquid crystal  26  is energized and displays information in a predetermined form, such as alphanumeric symbols or the like. 
     The polarizing seals  27  and  28  are also bonded to the polymer substrates  21  and  22 , respectively, on sides of the polymer substrates  21  and  22  opposite to those having the electrodes  23  and  24 , as shown in FIG.  3 . The polarizing seals  27  and  28  may be substituted by semi-transparent seals or reflective seals. 
     The polymer substrate  22  forms at one end a substrate extension  22   a  which extends in an external direction over the sealing member  25 . Along the substrate extension  22   a , the electrode  24  also forms an electrode extension  24   a  for a predefined length. Also, the polarizing seal  28  extends its end along the substrate extension  22   a  nearly to the ends of the substrate extension  22   a  and the electrode extension  24   a.    
     The electrode extension  24   a  which extends from the electrode  24  over the sealing member  25  is bent at a portion around the sealing member  25 , e.g., slightly outside the sealing member  25 , in a direction towards the polymer substrate  21  with an angle θ, which may be in the 2-degree to 20-degree range. Such a bent electrode extension  24   a  is installed in an assembling frame (explained later). The electrode  24  may alternatively be bent around its mid portion or any portion other than the portion around the sealing member  25 . 
     The electrode extension  24   a  is electrically connected, e.g., via bumps  31  to an electrode  30  of a connecting member  29  which is a part of a heat seal connector or the like mounted on a circuit substrate (not shown). The electrode  30  is fixed to the electrode extension  24   a  with, e.g., a solder  32 . Accordingly, the electrode  24  is connected to the connecting member  29  through the electrode extension  24   a  and can be applied with a power therethrough to cause the liquid crystal  26  to display information in a form such as alphanumeric symbols or the like. 
     In the present embodiment, the liquid crystal display apparatus  34  with the electrode extension  24   a  being bent with the angle θ within the 2-degree to 20-degree range allowance is assembled in an assembling frame. Then, the electrode extension  24   a  is made to contact the connecting member  29  via the bumps  31  with a pressure, and heat is applied to melt the solder between the electrode  30  and the electrode extension  24   a . Thereby, the electrode extension  24   a  is connected to the connecting member  29 . 
     In this way, the liquid crystal display apparatus  34  can be installed in the assembling frame with the electrode extension  24   a  which has previously been bent towards the polymer substrate  21  relative to the surface of the electrode  24 . Accordingly, when the liquid crystal display apparatus  34  is installed in the assembling frame, the electrode extension  24   a  is positioned at a place where it can contact the electrode  30  of the connecting member  29  without causing a mechanical stress thereon. Accordingly, the electrode extension  24   a  can be connected safely with the connecting member  29 . Even if a crack  33  occurs on the portion of the electrode  24  or the electrode extension  24   a  where the bend is made, the electrode extension  24   a  can be connected safely with the connecting member  29  since the electrode extension  24   a  will not receive a stress during the connecting process. As a result, the electrical connection can be made stably between the electrode  30  of the connecting member  29  and the electrode extension  24   a , which avoids a failure in displaying information. 
     As described above, the polarizing seal  28  also has an extended portion with the predetermined angle θ. This extended portion supports the electrode extension  24   a  from the bottom thereof, protecting the electrode extension  24   a  from being bent to an extent exceeding a predetermined angle and from generating the crack  33  around the portion being bent. 
     As also described above, the electrode extension  24   a  is bent with the angle θ within the 2-degree 20-degree range, thereby making good contact with the electrode  30  of the connecting member  29  even if the electrode extension  24   a  has the crack  33  at the portion where the bend is made. The experimental reasons for predetermining the angle θ within the 2-degree to 20-degree range are as follows. With the angle θ smaller than 2 degrees, the electrode extension  24   a  may need to be bent at a further angle during the process of connecting to the connecting member  29 . In this case, if the crack  33  already exists, such a crack  33  may become greater and, as a result, the electrode extension  24   a  may not make good contact with the electrode  30 . With the angle θ greater than 20 degrees, the electrode extension  24   a  may need to be bent back during the process of connecting to the connecting member  29 . In this case, if the crack  33  already exists, such a crack  33  may become greater and, as a result, the electrode extension  24   a  may not make good contact with the electrode  30 . Accordingly, the safety range of the angle θ is in the 2-degree to 20-degree range. This range may be expanded in certain cases, e.g. based on materials used for the elements. However, from a practical view point, it is more preferable to set the angle θ to a degree within a 5-degree to 15-degree range. 
     Alternative to the way of bending in which the electrode extension  24   a  is bent linearly, as shown in FIG. 3, the electrode extension  24   a  can be bent with a curve having a radius of curvature within a range from 10 mm to 100 mm, as shown in FIG.  4 . This alternative bending way provides a margin to the connecting tension between the electrode extension  24   a  and the connecting member  29 . Therefore, the electrode extension  24   a  can maintain a good contact with the electrode  30  of the connecting member  29  against an external stress even if the electrode extension  24   a  has the pre-formed crack  33  around the portions close to the sealing member  25  and/or the bumps  31  as well as the melted solder  32 , as shown in FIG.  4 . As described above, the range from 10 mm to 100 mm is the safety range of curvature radius. However, from a practical view point, it is more preferable to set the radius of curvature within a 15 mm to 50 mm range. 
     Next, a first example of an assembling frame which supports the liquid crystal display apparatus  34  is explained with reference to FIG.  5 . In FIG. 5, reference numeral  41  denotes an assembling frame which supports the liquid crystal display apparatus  34 . The assembling frame  41  includes a contact surface  41  a which contacts the side of the polymer substrate  21  of the liquid crystal display apparatus  34 . The assembling frame  41  further includes a side end  42  on which a pawl  42   a  is formed, as shown in FIG.  5 . 
     In FIG. 5, the liquid crystal display apparatus  34  and a back light mechanism (not shown) using, e.g., an LED (light-emitting diode) or an EL (electroluminescence) are assembled in the assembling frame  41 , and then the electrode extension  24   a  is engaged in the pawl  42   a  so that the electrode extension  24   a  is bent in the direction towards the side of the polymer substrate  21 . With this structure, the electrode extension  24   a  can be bent easily without requiring extra steps during the manufacturing procedure. As a result, the number of the assembling steps of the liquid crystal display apparatus  34  can be prevented from increasing. 
     In the assembling frame  41  of FIG. 5, the electrode extension  24   a  is set to the angle of 4 degrees when the length of the electrode extension  24   a  is 2.7 mm and when the pawl  42   a  is bent in the direction towards the side of the polarizing seal  27  so that the bottom surface of the pawl  42   a  is lowered 0.2 mm relative to the polarizing seal  27 . 
     Next, a second example of an assembling frame which supports the liquid crystal display apparatus  34  is explained with reference to FIG.  6 . In FIG. 6, reference numeral  51  denotes an assembling frame which supports the liquid crystal display apparatus  34 . The assembling frame  51  includes a contact surface  51  a which contacts the side of the polymer substrate  22  of the liquid crystal display apparatus  34 . The contact surface  51   a  has at one end a slope having an angle θ within a range from 2 degrees to 20 degrees. 
     With this structure, when the liquid crystal display apparatus  34  is installed in the assembling frame such that the side of the polymer substrate  22  faces the side of the contact surface  51   a , the electrode extension  24   a  is placed on this slope of the contact surface  51   a  and is accordingly bent in the direction towards the polymer substrate  21 . 
     After the above-described installation, the liquid crystal display apparatus  34  is fixed to the assembling frame  51  by a fixing member  52  which supports the assembling frame from the bottom thereof and the electrode extension  24   a  from the top. 
     With this structure, the electrode extension  24   a  can be bent easily without requiring extra steps during the manufacturing procedure. As a result, the number of the assembling steps of the liquid crystal display apparatus  34  can be prevented from increasing. 
     Next, a third example of an assembling frame which supports the liquid crystal display apparatus  34  is explained with reference to FIG.  7 . In FIG. 7, reference numeral  61  denotes an assembling frame which supports the liquid crystal display apparatus  34 . The assembling frame  61  includes a contact surface  61   a  which contacts the side of the polymer substrate  22  of the liquid crystal display apparatus  34 . The contact surface  61   a  has at one end a curving slopel having a curvature radius S within a range from 10 mm to 100 mm. 
     With this structure, when the liquid crystal display apparatus  34  is installed in the assembling frame such that the side of the polymer substrate  22  faces the side of the contact surface  61   a , the electrode extension  24   a  is placed on this curving slope of the contact surface  61   a  and is accordingly bent in the direction towards the polymer substrate  21 . 
     After the above-described installation, the liquid crystal display apparatus  34  is fixed to the assembling frame  61  by a fixing member  62  which supports the assembling frame from the bottom thereof and the electrode extension  24   a  from the top. 
     With this structure, the electrode extension  24   a  can be bent easily without the need of extra steps during the manufacturing procedure. As a result, the number of the assembling steps of the liquid crystal display apparatus  34  can be prevented from increasing. 
     Next, an exemplary structure of a machine console where the liquid crystal display apparatus  34  is installed is explained with reference to FIG.  8 . In FIG. 8, reference numeral  71  denotes a console of a machine such as a copying machine, a facsimile machine, or the like, in which the liquid crystal display apparatus  34  assembled in the assembling frame  61  is installed. The console  71  includes a printed circuit board (PCB)  72  at the inside bottom thereof, and a supporting member  71   a  which extends from the upper interior wall of the console  71  and holds down the electrode extension  24   a.    
     With this structure, the liquid crystal display apparatus  34  can be fixed in the console without requiring extra parts for holding down the fixing member  62 . Accordingly, it becomes possible to minimize the distance between the console  71  and the liquid crystal display apparatus  34  inside the console  71 . As a result, the console  71  can be made thinner. 
     In addition, with the above-described structure, the liquid crystal display apparatus  34  can be fixed to the fixing member  62  without using a dual-sided adhesive tape or the like. Accordingly, the number of the assembling steps of the liquid crystal display apparatus  34  can be prevented from increasing. 
     Obviously, numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein. 
     This document claims the priority rights of and is based on the subject matter described in Japanese patent application JPAP 10-170830 filed on Jun. 18, 1998, in the Japanese Patent Office, the entire contents of which are hereby incorporated by reference.