Patent Document

FIELD OF THE INVENTION 
   The present invention relates to flexible printed circuits (FPCs) for liquid crystal display (LCD) devices, and more particularly to a flexible printed circuit with increased signal bandwidth and a liquid crystal display device using the same. 
   GENERAL BACKGROUND 
   Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only are very thin but also provide good quality images with little power. 
   A typical LCD device includes a liquid crystal display panel, and a backlight module disposed adjacent to the liquid crystal display panel. A plurality of source electrodes and a plurality of gate electrodes are disposed on the liquid crystal display panel. Each source electrode includes a source electrode driving integrated circuit (IC). Each gate electrode includes a gate electrode driving IC. An FPC is generally used in an LCD device for joining the liquid crystal display panel and a printed circuit board (PCB). 
   Referring to  FIG. 6 , a conventional LCD  100  includes a liquid crystal display panel  11 , a backlight module  150  disposed adjacent to the liquid crystal display panel  11 , a frame  160  containing the backlight module  150 , a PCB  130  disposed adjacent to the frame  160 , an FPC  1  joining the liquid crystal display panel  11  and the PCB  130 , and a driving IC  15  disposed on the FPC  1 . 
   Referring to  FIG. 7 , the FPC  1  includes a substrate  10 , a plurality of input lines  120 , a plurality of output lines,  140 , and a resin layer  16 . The substrate  10  includes a first joint part  12  for joining to the PCB  130 , and a second joint part  14  for joining to the liquid crystal display panel  11 . The input lines  120  are formed on the first joint part  12 . The output lines  140  are formed on the second joint part  14 . The input lines  120  and output lines  140  are electrically conductive. 
   The driving IC  15  is disposed in a middle region of the substrate  10 . The input lines  120  of the FPC  1  are joined to the PCB  130 , and are also joined to the driving IC  15  for signal transmission from the PCB  130  to the driving IC  15 . The output lines  140  of the FPC  1  are joined to the liquid crystal display panel  11 , and are also joined to the driving IC  15  for signal transmission from the driving IC  15  to the liquid crystal display panel  11 . The resin layer  16  covers areas of both the input lines  120  and the output lines  140  that are around the driving IC  15 . An aligning mark  18  is formed beside the output lines  140 . 
   The input lines  120  and the output lines  140  are all rectangular, and a certain distance must be provided between each two adjacent input lines  120  and each two adjacent output lines  140  in order to avoid short circuits. When the number of driving signals is large, the areas of the first joint part  12  and the second joint part  14  must be correspondingly large in order to contain the large number of input and output lines  120 ,  140  that are needed for providing the large signal bandwidth. This results in a correspondingly very wide FPC  1 , and may render the LCD  100  unsuitable for certain compact electronic apparatuses. 
   What is needed, therefore, is a flexible printed circuit and a liquid crystal display device using the same that overcome the above-described deficiencies. 
   SUMMARY 
   In an exemplary embodiment, a flexible printed circuit includes a substrate. The substrate includes a plurality of first conductive lines and second conductive lines. The first conductive lines include a plurality of first patches. The second conductive lines include a plurality of second patches. The first patches are arranged side by side oppositely oriented relative to each other in alternating fashion. The second patches are arranged side by side oppositely oriented relative to each other in alternating fashion. The first conductive lines may for example be input lines, and the second conductive lines may for example be output lines. 
   Assuming that a size of the FPC of the exemplary embodiment is the same as a size of a conventional FPC, the amount of input lines of the FPC of the exemplary embodiment can be approximately twice the amount of input lines of the conventional FPC. Similarly, the amount of output lines of the FPC of the exemplary embodiment can be approximately twice the amount of output lines of the conventional FPC. Thus, the signal bandwidth of the FPC of the exemplary embodiment can be approximately twice the signal bandwidth of the conventional FPC. 
   In another exemplary embodiment, a liquid crystal display device includes a liquid crystal display panel and a flexible printed circuit joined to the liquid crystal display panel. The flexible printed circuit includes a substrate. The substrate includes a plurality of first conductive lines and second conductive lines. The first conductive lines include a plurality of first patches. The second conductive lines include a plurality of second patches. The first patches are arranged side by side oppositely oriented relative to each other in alternating fashion. The second patches are arranged side by side oppositely oriented relative to each other in alternating fashion. 
   Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic, side cross-sectional view of part of a liquid crystal display device using an FPC according to a first embodiment of the present invention. 
       FIG. 2  is a schematic, top plan view of the FPC of  FIG. 1  when the FPC is laid out flat. 
       FIG. 3  is a schematic, side cross-sectional view corresponding to line III-III of  FIG. 2 . 
       FIG. 4  is a schematic, top plan view of an FPC according to a second preferred embodiment of the present invention. 
       FIG. 5  is a schematic, top plan view of an FPC according to a third preferred embodiment of the present invention. 
       FIG. 6  is a schematic, side cross-sectional view of part of a conventional liquid crystal display device including an FPC. 
       FIG. 7  is a schematic, top plan view of the FPC of  FIG. 6  when the FPC is laid out flat. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Reference will now be made to the drawings to describe the preferred embodiments in detail. 
   Referring to  FIG. 1 , an LCD  200  includes a liquid crystal display panel  21 , a backlight module  250  disposed adjacent to the liquid crystal display panel  21 , a frame  260  containing the backlight module  250 , a PCB  270  disposed adjacent to the frame  260 , an FPC  2  interconnecting the liquid crystal display panel  21  and the PCB  270 , and a driving IC  25  disposed on the FPC  2 . 
   Referring to  FIG. 2 , the FPC  2  includes a substrate  20 , a plurality of electrically conductive input lines  210  having input patches  220 , a plurality of electrically conductive output lines  230  having output patches  240 , and a resin layer  26 . The substrate  20  includes a first joint part  22  for connecting to the PCB  270 , and a second joint part  24  for connecting to the liquid crystal display panel  21 . The input patches  220  are formed on the first joint part  22 . The output patches  240  are formed on the second joint part  24 . 
   Referring to  FIG. 3 , the driving IC  25  is disposed in a middle region of the substrate  20 . Outer ends of the input lines  210  of the FPC  2  are connected to the PCB  270 . Inner ends of the input lines  210  are joined to a plurality of pins  251  of the driving IC  25 . Thus the input lines  210  provide signal transmission from the PCB  270  to the driving IC  25 . Outer ends of the output lines  230  of the FPC  2  are connected to the liquid crystal display panel  21 . Inner ends of the output lines  230  are joined to a plurality of pins  252  of the driving IC  25 . Thus the output lines  230  provide signal transmission from the driving IC  25  to the liquid crystal display panel  21 . The resin layer  26  covers portions of the input lines  210  and the output lines  230  around the driving IC  25 . The resin layer  26  can fix the driving IC  25  in place. An aligning mark  28  is formed beside the output patches  240 . 
   The input patches  220  and the output patches  240  are all shaped as isosceles triangles. In the illustrated embodiment, the input patches  220  and the output patches  240  all have the same size and shape. The input patches  220  are arranged generally in a row. Each input patch  220  has a point between the two sides of the triangle that are the same length. The points of every second input patch  220  in the row of input patches  220  face toward the outside of the substrate  20 . The points of every other input patch  220  in the row of input patches  220  face toward the driving IC  25 . That is, each two adjacent input patches  220  are oriented diametrically opposite each other. In other words, in general, a portion of one input patch  220  having a smaller width is opposite a portion of an adjacent input patch  220  having a larger width. Thus the row of input patches  220  comprises oppositely oriented input patches  220  arranged side by side in alternating fashion. The output patches  240  are arranged in a row, in essentially the same way that the input patches  220  are arranged. 
   Each input patch  220  has a base side opposite from the point. Each output patch  240  has a base side opposite from the point. A width of the base side of each input patch  220  is equal to a width of the base side of each output patch  240 . Distances between adjacent input patches  220  are the same. Distances between adjacent output patches  240  are the same. 
   The width of the base side of each input conductive pattern  220  is the same as the width of each input line  120  of the above-described conventional FPC  1 . Similarly, the width of the base side of each output patch  240  is the same as the width of each output line  140  of the FPC  1 . The distance between each two adjacent input patches  220  is similar to or somewhat less than the distance between each two adjacent input lines  120  of the FPC  1 . The distance between each two adjacent output patches  240  is similar to or somewhat less than the distance between each two adjacent output lines  140  of the FPC  1 . In general, a region that can contain only one input line  120  is able to contain two adjacent input patches  220 . In other words, assuming that a size of the FPC  2  is the same as a size of the FPC  1 , the amount of input lines  210  of the FPC  2  can be approximately twice the amount of input lines  120  of the FPC  1 . Similarly, the amount of output lines  230  of the FPC  2  can be approximately twice the amount of output lines  140  of the FPC  1 . Thus, the signal bandwidth of the FPC  2  can be approximately twice the signal bandwidth of the FPC  1 . 
   Referring to  FIG. 4 , an FPC  3  of the second embodiment of the present invention is similar to the FPC  2  of the first embodiment. However, the FPC  3  includes a plurality of electrically conductive input lines having input patches  320 , and a plurality of electrically conductive output lines having output patches  340 . The input patches  320  and the output patches  340  are all shaped as diamonds. In the illustrated embodiment, the input patches  320  and the output patches  340  all have the same size and shape. The input patches  320  are arranged generally in two rows. Each input patch  320  in each row is located generally midway between two nearest input patches  320  in the other row. Thus the two rows of input patches  220  have the input patches  220  arranged in a staggered fashion. The output patches  340  are arranged generally in two rows, in essentially the same way that the input patches  220  are arranged. 
   A maximum transverse width of each input patch  320  is equal to a maximum transverse width of each output patch  340 . Distances between adjacent input patches  320  are the same. Distances between adjacent output patches  340  are the same. 
   The maximum transverse width of each input patch  320  is the same as the width of each input line  120  of the above-described conventional FPC  1 . Similarly, the maximum transverse width of each output patch  340  is the same as the width of each output line  140  of the FPC  1 . The distance between each two adjacent input patches  320  is similar to or somewhat less than the distance between each two adjacent input lines  120  of the FPC  1 . The distance between each two adjacent output patches  340  is similar to or somewhat less than the distance between each two adjacent output lines  140  of the FPC  1 . In general, a region that can contain only one input line  120  is able to contain two adjacent input patches  320 . In other words, assuming that a size of the FPC  3  is the same as the size of the FPC  1 , the amount of input lines of the FPC  3  can be approximately twice the amount of input lines  120  of the FPC  1 . Similarly, the amount of output lines of the FPC  3  can be approximately twice the amount of output lines  140  of the FPC  1 . Thus, the signal bandwidth of the FPC  3  can be approximately twice the signal bandwidth of the FPC  1 . 
   Referring to  FIG. 5 , an FPC  4  of the third embodiment of the present invention is similar to the FPC  2  of the first embodiment. However, the FPC  4  includes a plurality of electrically conductive input lines having input patches  420 , and a plurality of electrically conductive output lines having output patches  440 . The input patches  420  and the output patches  440  are all shaped as right-angled triangles. The input patches  420  are arranged generally in a row. Each input patch  420  has a point that is distalmost from the right angle. The points of every second input patch  420  in the row of input patches  420  face toward the outside of a substrate (not labeled) of the FPC  4 . The points of every other input patch  420  in the row of input patches  420  face toward a central driving IC (not labeled). That is, each two adjacent input patches  420  are oriented diametrically opposite each other. In other words, in general, a portion of one input patch  420  having a smaller width is opposite a portion of an adjacent input patch  420  having a larger width. Thus the row of input patches  420  comprises oppositely oriented input patches  420  arranged side by side in alternating fashion. The output patches  440  are arranged in a row, in essentially the same way that the input patches  420  are arranged. 
   Each input patch  420  has a base side opposite from the point. Each output patch  440  has a base side opposite from the point. A width of the base side of each input patch  420  is equal to a width of the base side of each output patch  440 . Distances between adjacent input patches  420  are the same. Distances between adjacent output patches  440  are the same. 
   The width of the base side of each input patch  420  is the same as the width of each input line  120  of the above-described conventional FPC  1 . Similarly, the width of the base side of each output patch  440  is the same as the width of each output line  140  of the FPC  1 . The distance between each two adjacent input patches  420  is similar to or somewhat less than the distance between each two adjacent input lines  120  of the FPC  1 . The distance between each two adjacent output patches  440  is similar to or somewhat less than the distance between each two adjacent output lines  140  of the FPC  1 . In general, a region that can contain only one input line  120  is able to contain two adjacent input patches  420 . In other words, assuming that a size of the FPC  4  is the same as the size of the FPC  1 , the amount of input lines of the FPC  4  can be approximately twice the amount of input lines  120  of the FPC  1 . Similarly, the amount of output lines of the FPC  4  can be approximately twice the amount of output lines  140  of the FPC  1 . Thus, the signal bandwidth of the FPC  4  can be approximately twice the signal bandwidth of the FPC  1 . 
   It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.

Technology Category: 5