JP2005338699A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an open circuit in a FPC (flexible printed circuit board) and to improve reliability as well as to provide an inexpensive liquid crystal display. <P>SOLUTION: The liquid crystal display comprises a liquid crystal display panel 4 and a flexible printed circuit board 10 connected to the liquid crystal display panel 4, wherein the flexible printed circuit board 10 comprises: a base film 10 connected to the connecting part 4e of the liquid crystal display panel 4; a coverlay 10e applied on one surface of the base film 10f; a molding member 22 to cover the coverlay opening 10g between the end of the coverlay 10e and the end of liquid display panel 4 and where the base film 10f is exposed; a first reinforcing tape 24 the one end 24a of which is connected to the liquid crystal display panel 4 and the other end 24b of which is adhered to the coverlay 10e to cover the molding member 22; and a second reinforcing tape 26 adhered to the other surface of the base film 10f and in the position opposing the first reinforcing tape 24. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to protection and reinforcement of a connection portion between a flexible wiring board and a liquid crystal display panel.

  As a conventional liquid crystal display device of this type, for example, a first conventional one having a backlight, there has been one having the structure shown in FIGS. FIG. 6 is a cross-sectional view showing the liquid crystal display device, and FIG. 8 is a plan view of the FPC. As shown in FIGS. 6 and 8, in the liquid crystal display device according to the first conventional example, the frame 2, the liquid crystal display panel 4 housed in the frame 2, and the liquid crystal display panel 4 are provided below. A light guide plate 6 disposed, a diffusion plate 8 disposed between the liquid crystal display panel 4 and the light guide plate 6, a flexible wiring substrate (hereinafter referred to as “FPC”) 10 connected to the liquid crystal display panel 4, And a light emitting element 12 such as an LED mounted on the FPC 10.

  The liquid crystal display panel 4 includes an upper glass 4a, a lower glass 4b, an upper polarizing plate 4c provided on the upper surface of the upper glass 4a, and a lower polarizing plate 4d provided on the lower surface of the lower glass 4b. Liquid crystal is sealed between the glass 4a and the lower glass 4b. The liquid crystal display panel 4 is provided with a connection portion 4e at an end portion of the upper glass 4a (or the lower glass 4b). On the other hand, the FPC 10 has a base film 10f having a conductive pattern 10d formed on the surface and a connection portion 10c at the end, and a region A excluding the connection portion 10c as shown in FIG. 8 in order to protect the conductive pattern 10d. The coverlay 10e is provided. The FPC 10 is electrically connected to and attached to the liquid crystal display panel 4 by crimping a connection portion 10c provided at an end thereof to the connection portion 4e of the upper glass 4a of the liquid crystal display panel 4.

  As shown in FIG. 8, the light emitting element 12 is mounted on a protruding portion 10 b branched from the main body 10 a of the FPC 10, and the light emitting element 12 is positioned on the inner surface of the bottom portion of the frame 2 by drawing the protruding portion 10 b. The light guide plate 6 can be irradiated with light from an optimal position such as the side of the light guide plate 6. When the light emitting element 12 is routed as described above, it may be necessary to bend the main body 10a not only from the protruding portion 10b of the FPC 10 but from the side of the frame body 2 downward.

  The base film 10f of the FPC 10 is covered with the cover lay 10e in the area A except for the connecting portion 10c. However, due to variations in dimensions in forming each part, a cover lay opening 10g not covered with the cover lay 10e is generated. Thus, part of the base film 10f may be exposed. The cover lay opening 10g has a low strength and is easily bent. When the FPC 10 is bent as described above, the bent portion is a portion constituted only by the base film 10f, that is, the cover lay opening 10g is bent. When the base film 10f located in the cover lay opening 10g is bent, cracks may occur in the conductive pattern 10d on the base film 10f due to the expansion and contraction at that time, which may cause disconnection.

  Therefore, a second conventional example of a liquid crystal display device is disclosed in which the problem of the first prior art is solved and the connection portion between the liquid crystal display panel and the FPC is protected and reinforced to prevent disconnection of the FPC. (For example, refer to Patent Document 1). FIG. 7 is a cross-sectional view of a liquid crystal display device according to a second conventional example. Since the basic configuration of the liquid crystal display device in the second conventional example is similar to that of the first conventional example, the same reference numerals are given to the same components and the description thereof is omitted.

  As shown in FIG. 7, the liquid crystal display device of the second conventional example includes a liquid crystal display panel 4 and an FPC 10 connected to the liquid crystal display panel 4. The FPC 10 covers a base film 10f and a cover layer covering its surface. 10e, and a connecting portion 10c provided at an end of the base film 10f protruding from the cover lay 10e is connected to the connecting portion 4e of the liquid crystal display panel 4. A mold member 22 is provided so as to cover the cover lay opening 10g where the base film 10f generated between the liquid crystal display panel 4 and the cover lay 10e is exposed, and a reinforcing tape 24 is provided so as to cover the mold member 22. It has been. The reinforcing tape 24 has one end 24a connected to the liquid crystal display panel 4 and the other end 24b bonded to the cover lay 10e. Thus, even when the FPC 10 is bent, the reinforcing tape 24 and the mold member 22 prevent the coverlay opening 10g having a low strength from being bent as a fulcrum, and the conductive pattern near the coverlay opening 10g is prevented. The disconnection can be prevented.

JP2003-249526A (page 3-4, FIG. 1)

  However, the FPC 10 has recently been required to be greatly bent at a position closer to the liquid crystal display panel 4 than the conventional one. For this reason, also in the liquid crystal display device in the second conventional example, the FPC 10 is most easily bent at the position of the end portion 10h of the cover lay 10e of the cover lay opening 10g, and the conductive pattern on the base film 10f is expanded and contracted at this time. A crack occurred in 10d and the wire was sometimes disconnected. When such a disconnection occurs, the yield decreases, and the cost increases due to the correction / replacement and the like, and the improvement of the yield has been a problem.

(Object of invention)
The object of the present invention has been made in view of this point, and by protecting and reinforcing the connection portion between the liquid crystal display panel and the FPC, the FPC is greatly bent at a position closer to the liquid crystal display panel. In such a case, it is an object to provide a liquid crystal display device that prevents disconnection of the FPC, improves yield, reduces costs, and has excellent reliability.

  In order to achieve the above object, a liquid crystal display device of the present invention is a liquid crystal display device comprising a liquid crystal display panel and a flexible wiring substrate connected to the liquid crystal display panel, wherein the flexible wiring substrate is a connecting portion of the liquid crystal display panel. A base film connected to the cover film, a cover lay provided on one surface of the base film, and a cover lay opening where the base film generated between the end of the cover lay and the end of the liquid crystal display panel is exposed A mold member, a first reinforcing tape having one end connected to the liquid crystal display panel and the other end bonded to the cover lay so as to cover the mold member; and a first reinforcing tape bonded to the other surface of the base film And a second reinforcing tape provided at a position opposite to.

  The first and second reinforcing tapes have different bending stiffnesses, and the value of the bending stiffness of the reinforcing tape located on the surface of the flexible wiring board on the bending direction side is located on the surface opposite to the bending direction. The reinforcing tape is set to a value larger than the value of the bending rigidity of the reinforcing tape.

  The second reinforcing tape is characterized in that its width is set to be substantially equal to the width of the base film, and its length is set to be substantially equal to the length of the first reinforcing tape.

  Further, the mold member is characterized by having elasticity.

The first reinforcing tape covers a part or all of the mold member.
Further, the first reinforcing tape is set to be slightly longer than the length of the upper surface of the mold member, and covers the mold member.

  As described above, according to the liquid crystal display device of the present invention, even when the FPC is greatly bent, the bending rigidity of the cover lay opening is increased by providing the first and second reinforcing tapes and the mold member. The cover lay opening serves as a fulcrum to prevent it from being bent greatly. As a result, disconnection of the conductive pattern in the vicinity of the cover lay opening can be eliminated, yield can be improved, and reliability can be improved.

  The first and second reinforcing tapes have different bending stiffnesses, and the value of the bending stiffness of the reinforcing tape located on the surface of the flexible wiring board on the bending direction side is located on the surface opposite to the bending direction. By setting it to a value larger than the bending rigidity value of the reinforcing tape, the cover lay opening is prevented from bending at the cover lay opening with low strength in any bending direction. The nearby conductive pattern is not disconnected, and the yield can be improved. Furthermore, it can respond to any bending direction.

  Further, by improving the yield as described above, it is possible to greatly reduce the work and cost related to the correction, disposal or inspection of defective products, and as a result, it is possible to reduce the manufacturing cost. .

  In the liquid crystal display device of the present invention, when the connection portion provided at the end portion of the base film of the FPC is connected to the connection portion of the liquid crystal display panel, the coverlay provided on one surface of the base film is interposed between the liquid crystal display panel. A mold member is provided to cover the cover lay opening where the resulting base film is exposed. A first reinforcing tape is provided on the mold member, and one end thereof is bonded to the liquid crystal display panel and the other end is bonded to the cover lay so as to cover the mold member. Furthermore, the 2nd reinforcement tape provided in the position which adhere | attaches on the other surface of a base film and opposes a 1st reinforcement tape is provided.

  According to the liquid crystal display device of the present invention, the bending rigidity of the cover lay opening is increased by providing the first and second reinforcing tapes and the mold member, and the cover lay opening is a fulcrum even when the FPC is greatly bent. To prevent it from bending greatly. Thereby, disconnection of the conductive pattern in the vicinity of the cover lay opening can be eliminated.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show a liquid crystal display device according to the present embodiment, and FIGS. 4 and 5 are cross-sectional views of main parts showing a bent state in the present embodiment. Since the basic configuration of the liquid crystal display device in the present embodiment is similar to that of the above-described second conventional example, the same components are assigned the same reference numerals and the description thereof is omitted.

  1A and 1B show a liquid crystal display device according to an embodiment of the present invention. FIG. 1A is a cross-sectional view, and FIG. 1B is an enlarged cross-sectional view of a portion A in FIG. 2 is a plan view of the liquid crystal display device shown in FIG. 1 viewed from the upper surface side, and FIG. 3 is a plan view of the liquid crystal display device shown in FIG. 1 viewed from the lower surface side. The basic configuration of the liquid crystal display device in this embodiment is similar to the conventional example. Further, the frame 2, the liquid crystal display panel 4, the light guide plate 6, and the diffusion plate 8 are the same as those in the conventional example, and thus the description thereof is omitted. The basic configuration of the FPC 10 is the same as that of the conventional example shown in FIG.

  As shown in FIG. 1, the FPC 10 in this embodiment is electrically connected to the liquid crystal display panel 4 by crimping the connection portion 10c provided at the end thereof to the connection portion 4e of the upper glass 4a of the liquid crystal display panel 4. And attached. The FPC 10 includes a base film 10f connected to the connection portion 4e of the liquid crystal display panel 4, and a cover lay 10e provided on one surface of the base film 10f. Further, the cover lay opening 10g where a part of the base film 10f generated between the end 10h of the cover lay 10e and the end 4f of the upper glass 4a of the liquid crystal display panel 4 is exposed is molded so as to cover it. A member 22 is provided, and a first reinforcing tape 24 is provided so as to cover the upper surface of the mold member 22. A second reinforcing tape 26 is provided on the other surface of the base film 10f.

  The mold member 22 is formed by applying a molding material such as silicon resin or UV resin. The mold member 22 is provided between the end portion of the upper glass 4a of the liquid crystal display panel 4 and the cover lay 10e of the FPC 10 when the connection portion 10c of the FPC 10 is crimped and connected to the connection portion 4e of the liquid crystal display panel 4. It is formed so as to cover the generated coverlay opening 10g.

  The first reinforcing tape 24 is made of polyethylene resin or the like. As shown in FIGS. 1 and 2, one end 24a is bonded to the upper surface of the end portion of the upper glass 4a of the liquid crystal display panel 4, and the other end 24b is a cover of the FPC 10. It is bonded to the upper surface of the end of the ray 10e. The first reinforcing tape 24 is stretched linearly over the mold member 22. As shown in FIG. 2, the width of the first reinforcing tape 24 is set so as to cover a part of the mold member 22 formed to fill the width of the cover lay opening 10 g of the FPC 10. The width may be set so as to cover the entire mold member 22.

  The second reinforcing tape 26 is made of polyethylene resin or the like, and is bonded to a position facing the first reinforcing tape 24 on the other surface of the base film 10f as shown in FIGS. The width of the second reinforcing tape 26 is set substantially equal to the width of the base film 10 f, and the length is set substantially equal to the length of the first reinforcing tape 24. Moreover, it is preferable to match | combine the position to stick in a length direction with the position corresponding to a 1st reinforcement tape.

  As described above, in the FPC 10 of this embodiment, the mold member 22 is provided in the cover lay opening 10g, and the first reinforcing tape 24 is bonded so as to cover the mold member 22. Furthermore, the second reinforcing tape 26 adheres to the base film 10f, so that the base film 10f is integrated with the second reinforcing tape 26, thereby increasing the strength of the base film 10f, and the periphery of the cover lay opening 10g around the base film 10f. Strength can be reinforced. Further, the portion where the first reinforcing tape 24 and the second reinforcing tape 26 of the FPC 10 are affixed is thicker and the bending rigidity is larger than the other portions. Accordingly, it is possible to prevent the vicinity of the cover lay opening 10g from being bent as a fulcrum, and to reduce deformation with respect to the bending force in the vicinity of the cover lay opening 10g. Further, the portion where the first reinforcing tape 24 and the second reinforcing tape 26 of the FPC 10 are affixed is a wedge shape whose thickness gradually increases from the end of the cover lay 10e toward the end of the upper glass 4a. The bending rigidity increases from the cover lay 10e toward the upper glass 4a, and the deformation with respect to the bending force becomes smaller. As a result, the FPC 10 can be smoothly deformed.

  Further, the first and second reinforcing tapes 24 and 26 have different bending rigidity, and the bending rigidity value of the reinforcing tape located on the surface on the bending direction side of the FPC 10 is set on the surface opposite to the bending direction. The effect of reinforcement can be increased by setting the value larger than the value of the bending rigidity of the reinforcing tape. A specific example will be described with reference to FIGS. 4 is a cross-sectional view showing an example in which the FPC 10 is bent toward the base film 10f side, that is, the second reinforcing tape 26 side, and FIG. 5 is an example in which the FPC 10 is bent toward the cover lay 10e side, that is, the first reinforcing tape 24 side. It is sectional drawing shown.

  As shown in FIG. 4, when the FPC 10 is bent toward the second reinforcing tape 26, the value of the thickness b of the second reinforcing tape 26 is larger than the value of the thickness a of the first reinforcing tape 24. By setting, the bending rigidity of the second reinforcing tape 26 is set larger than the bending rigidity of the first reinforcing tape 24. In this case, it is preferable that the mold member 22 is not hard and has an appropriate elasticity.

  When a force to bend in the direction of the second reinforcing tape 26 is applied to the FPC 10, the base film 10f is pressed against the second reinforcing tape 26, and the second reinforcing tape 26 is compressed but has a high rigidity and a base film. By integrating 10f with the second reinforcing tape 26, the strength is increased and the shape is not easily deformed and is easily maintained. On the other hand, the first reinforcing tape 24 is stretched together with the elastic mold member 22 and slightly deformed in the direction in which the FPC 10 is bent, so that the FPC 10 can be bent so as to gradually bend from the vicinity of the cover lay opening 10g. Further, the portion where only the base film 10f and the cover lay 10e overlap is thin and easy to bend. Therefore, the FPC 10 can be bent without difficulty in a narrow range so that the vicinity of the cover lay opening 10g is slightly bent. Therefore, the FPC can be smoothly deformed, and the conductive pattern 10d on the base film 10e is not disconnected.

  In this example, if the rigidity of the first reinforcing tape 24 and the mold member 22 is increased and hardened, the adhesion between the first reinforcing tape 24 and the mold member 22 and the cover lay 10e is peeled off. The thickness of the FPC 10 is the same as that of the thin state, and the FPC 10 is easily deformed and the effect of reinforcement is reduced.

  Next, as shown in FIG. 5, the case where the FPC 10 is bent toward the first reinforcing tape 24 will be described. In this case, by setting the value of the thickness b of the second reinforcing tape 26 to be smaller than the value of the thickness a of the first reinforcing tape 24, the bending rigidity of the second reinforcing tape 26 is set to the first value. It is set smaller than the bending rigidity of the reinforcing tape 24. Further, it is preferable that the mold member 22 has a small elasticity and is kept in a hard state. In order to change the elasticity of the mold member 22, the material may be changed.

  When a force that bends in the direction of the first reinforcing tape 24 is applied to the FPC 10, the mold member 22 is pressed against the first reinforcing tape 24 and the first reinforcing tape 24 is compressed, but the first reinforcing tape is used. Since the rigidity of 24 is large and the mold member 22 is in a hard state, it is difficult to be deformed and the shape can be easily maintained. This prevents deformation and prevents the vicinity of the cover lay opening 10g from being bent greatly. On the other hand, the second reinforcing tape 26 is integrated with the base film 10f. However, since the second reinforcing tape 26 is thin and has low bending rigidity, the FPC 10 is slightly deformed in the bending direction, and the coverlay opening is formed. The FPC 10 can be bent so as to bend gradually from the vicinity of the portion 10g. In addition, as described above, since the portion where only the base film 10f and the cover lay 10e overlap is thin and easy to bend, the first and second reinforcing tapes can be bent greatly from the position where they are removed, The FPC 10 can be bent in the direction of the first reinforcing tape 24 so that the vicinity of the cover lay opening 10 g is slightly bent. Therefore, the FPC can be smoothly deformed, and the conductive pattern 10d on the base film 10e is not disconnected.

  As described above, according to the present embodiment, even when the FPC 10 is largely bent near the liquid crystal display panel 4, there is no conductor breakage at the cover lay opening 10g of the FPC 10, and disconnection of the conductive pattern 10d can be eliminated. As a result, the reliability is improved, the yield is improved, and an inexpensive liquid crystal display device can be provided.

In the present embodiment, the example in which the bending rigidity is changed by changing the thickness of the first and second reinforcing tapes 24 and 26 has been described, but the present invention is not limited to this. The material of the second reinforcing tapes 24 and 26 may be changed.
Further, although the example in which the FPC 10 is connected to the upper glass 4a has been described, the present invention can be similarly applied to the case where the connection portion is formed on the upper surface of the end portion of the lower glass 4b and the same effect can be obtained.

It is sectional drawing which shows the liquid crystal display device based on the Example of this invention. It is a top view from the upper surface side of the liquid crystal display device shown in FIG. It is a top view from the lower surface side of the liquid crystal display device shown in FIG. It is principal part sectional drawing which shows the bending state in the Example of this invention. It is principal part sectional drawing which shows the bending state in the Example of this invention. It is sectional drawing which shows the liquid crystal display device in a 1st prior art. It is sectional drawing which shows the liquid crystal display device in a 2nd prior art. FIG. 8 is a plan view of the FPC shown in FIGS. 1 to 7.

Explanation of symbols

2 Frame 4 Liquid Crystal Display Panel 4a Upper Glass 4b Lower Glass 4e Upper Glass Connection 4f Upper Glass Edge 6 Light Guide Plate 8 Diffuser 10 Flexible Wiring Board (FPC)
10c Connecting portion 10d Conductive pattern 10e Coverlay 10f Base film 10g Coverlay opening 10h Coverlay end 12 Light emitting element 22 Mold member 24 First reinforcing tape 26 Second reinforcing tape

Claims (6)

In a liquid crystal display device comprising a liquid crystal display panel and a flexible wiring board connected to the liquid crystal display panel,
The flexible wiring board includes a base film connected to a connection portion of the liquid crystal display panel, a cover lay provided on one surface of the base film, an end portion of the cover lay, and an end portion of the liquid crystal display panel A mold member that covers a cover lay opening that exposes the base film that is formed in between, and a first member that is connected to the liquid crystal display panel at one end and adhered to the cover lay to cover the mold member. A liquid crystal display device comprising: a reinforcing tape; and a second reinforcing tape that is adhered to the other surface of the base film and provided at a position facing the first reinforcing tape.   The first and second reinforcing tapes have different bending rigidity, and the bending rigidity value of the reinforcing tape located on the surface of the flexible wiring board on the bending direction side is located on the surface opposite to the bending direction. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is set to a value larger than the value of the bending rigidity of the reinforcing tape.   The width of the second reinforcing tape is substantially equal to the width of the base film, and the length is set to be substantially equal to the length of the first reinforcing tape. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the mold member has elasticity.   5. The liquid crystal display device according to claim 1, wherein the first reinforcing tape covers a part or all of the mold member. 6.   6. The liquid crystal display device according to claim 1, wherein the first reinforcing tape is set to be slightly longer than a length of an upper surface of the mold member and covers the mold member.

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