Patent Publication Number: US-2015070298-A1

Title: Touch panel and liquid crystal display device using the same

Description:
RELATED APPLICATIONS 
     This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 201310404921.X, filed on Sep. 9, 2013 in the China Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present application relates to a touch panel and liquid crystal display device using the same. 
     2. Discussion of Related Art 
     Following the advancement in recent years of various electronic apparatuses, such as mobile phones, car navigation systems and the like toward high performance and diversification, there has been continuous growth in the number of electronic apparatuses equipped with optically transparent touch panels at the front of their respective display devices (e.g., a display such as a liquid crystal panel). A user of any such electronic apparatus operates it by pressing or touching the touch panel with a finger, a pen, a stylus, or a like tool while visually observing the display device through the touch panel. Therefore, a demand exists for touch panels that are superior in visibility and reliable in operation. 
     At present, different types of touch panel include resistance-type and capacitance-type. The capacitance-type touch panel has several advantages, such as high accuracy and strong anti jamming ability, and thus has been widely used. Different types of capacitance-type touch panel include mutual-inductance capacitance touch panel and self-inductance capacitance touch panel. The self-inductance capacitance touch panel has several advantages, such as simple structure, simple drive mode and mature preparation technology. 
     As shown in  FIG. 9 , a conventional self-inductance capacitance touch panel  10  includes a substrate  12 , a transparent conductive layer  14  located on the substrate  12 , a protective layer  16  located on the transparent conductive layer  14 , and at least two wires  18  spaced to each other. The at least two wires  18  are electrically connected to the transparent conductive layer  14 . 
     In the conventional self-inductance capacitance touch panel  10 , conventional patterns of the transparent conductive layer  14  are right triangles, as shown in  FIGS. 9 and 10 . The transparent conductive layer  14  is etched to a plurality of right triangles, and pixels in a liquid crystal display module are often arranged in rows and columns in horizontal and vertical directions. Thus, when the self-inductance capacitance touch panel  10  is assembled with the liquid crystal display module, an etching direction of an angle right in the transparent conductive layer  14  is parallel with the pixels arrangements of the liquid crystal display module, causing interference of light. As a result, Moire&#39; effects can appear. In general, Moire&#39; effects can be produced by two overlapping entities with regular patterns, and can appear as a regular patter of lines that can be more pronounced if the periodicity of the pattern of one entity is an integer multiple of the periodicity of the pattern of the second entity. Moire&#39; effects can affect visual identification and operation to the self-inductance capacitance touch panel  10 . 
     What is needed, therefore, is to provide a touch panel and liquid crystal display device using the same that can overcome the above-described shortcomings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the embodiments can be better understood with references to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic view of one embodiment of a touch panel. 
         FIG. 2  is a schematic view of one embodiment of patterns of a transparent conductive layer in the touch panel of  FIG. 1 . 
         FIG. 3  is another schematic view of one embodiment of patterns of a transparent conductive layer in the touch panel of  FIG. 1 . 
         FIG. 4  is yet another schematic view of one embodiment of patterns of a transparent conductive layer in the touch panel of  FIG. 1 . 
         FIG. 5  is a schematic view of one embodiment of a zigzag shape in the transparent conductive layer of  FIGS. 2-4 . 
         FIG. 6  is a schematic view of one embodiment of a liquid crystal display device. 
         FIG. 7  is a schematic view of another embodiment of patterns of a transparent conductive layer in the touch panel of  FIG. 1 . 
         FIG. 8  is a schematic view of yet another embodiment of patterns of a transparent conductive layer in the touch panel of  FIG. 1 . 
         FIG. 9  is a schematic view of a conventional self-inductance capacitance touch panel of the prior art. 
         FIG. 10  is a schematic view of a conventional patterns of a transparent conductive layer of the prior art. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. 
     Referring to  FIG. 1 , a touch panel  20  of one embodiment includes a substrate  22 , a transparent conductive layer  24 , a protective layer  26  and at least two wires  28 . The substrate  22  has a first surface  221  and a second surface  222  opposite to the first surface  221 . The transparent conductive layer  24  is located on the first surface  221  of the substrate  22 . The at least two wires  28  are electrically connected with the transparent conductive layer  24 . The protective layer  26  is directly located on the transparent conductive layer  24 . In one embodiment, the touch panel  20  only includes one transparent conductive layer  24 . That is, the touch panel  20  can be a single-touch sensor panel, and operated by multi-points in part area. 
     The substrate  22  for supporting other elements can be a transparent thin film or transparent thin plate. The substrate  22  can be made of rigid materials such as glass, quartz, diamond or any other suitable material. The substrate  22  can also be made of flexible materials such as polycarbonate (PC), polymethyl methacrylate acrylic (PMMA), polyimide (PI), polyethylene terephthalate (PET), polyethylene (PE), polyether polysulfones (PES), polyvinyl polychloride (PVC), benzocyclobutenes (BCB), polyesters, or acrylic resin. A thickness of the substrate  22  can be in a range from about 1 millimeter to about 1 centimeter. In one embodiment, the substrate  22  is made of PET, the thickness of the substrate  22  is about 2 millimeters. 
     Referring to  FIGS. 2 and 3 , the transparent conductive layer  24  is a patterned transparent conductive layer. The pattern is configured as a plurality of right triangles, as shown in  FIG. 2 . The pattern is also configured as a plurality of right angled trapezoids, as shown in  FIG. 3 . There are an X direction and a Y direction perpendicular to the X direction in one plane parallel to a surface of the transparent conductive layer  24 . 
     The transparent conductive layer  24  is etched or patterned to a plurality of pairs of sensor electrodes  240  spaced with each other and arranged adjacent to each other in the X direction. That is, the transparent conductive layer  24  includes a plurality of pairs of sensor electrodes  240  arranged adjacent to each other in the X direction. A distance between two adjacent pairs of sensor electrodes  240  is equal. The distance between two adjacent pairs of sensor electrodes  240  can be in a range from about 0.02 millimeters to about 0.3 millimeters. In one embodiment, the distance between two adjacent pairs of sensor electrodes  240  is about 0.03 millimeters. 
     Each of the plurality of pairs of sensor electrodes  240  includes a first electrode  242  and a second electrode  244  spaced to each other. In each of the plurality of pairs of sensor electrodes  240 , a distance between the first electrode  242  and the second electrode  244  can be in a range from about 0.02 millimeters to about 0.3 millimeters. In one embodiment, the distance between the first electrode  242  and the second electrode  244  is 0.03 millimeters. 
     As shown in  FIG. 2 , a pattern of the first electrode  242  is generally a right triangle with a saw like side. The pattern of the first electrode  242  has a first side  2421 , a second side  2423  parallel to the X direction and a third side  2425 . The second side  2423  has a first end a 1  and a second end a 2  opposite to the first end a 1 . The third side  2425  has the first end a 1  and a third end a 3  opposite to the first end a 1 . The second side  2423  is connected to the third side  2425  by the first end a 1 . If the second end a 2  is connected with the third end a 3  by a straight line, the straight line is perpendicular to the second side  2423 . The first side  2421  connecting the second end a 2  with the third end a 3  is curved or formed in zigzag patterns. 
     As shown in  FIG. 2 , a pattern of the second electrode  244  is also generally a right triangle with a saw like side. The pattern of the second electrode  244  has a fourth side  2441 , a fifth side  2443  parallel to the X direction and a sixth side  2445 . The fifth side  2443  has a fourth end b 1  and a fifth end b 2  opposite to the fourth end b 1 . The sixth side  2445  has the fourth end b 1  and a sixth end b 3  opposite to the fourth end b 1 . The fifth side  2443  is connected to the sixth side  2445  by the fourth end b 1 . If the fifth end b 2  is connected with the sixth end b 3  by a straight line, the straight line is perpendicular to the fifth side  2443 . The fourth side  2441  connecting the fifth end b 2  with the sixth end b 3  is curved or formed in zigzag patterns. 
     As shown in  FIG. 3 , a pattern of the first electrode  242  is generally a right angled trapezoid with a saw like side. The pattern of the first electrode  242  has the first side  2421 , the second side  2423  parallel to the X direction, the third side  2425 , and a seventh side  2427  opposite to the second side  2423  and parallel to the X direction. The second side  2423  is connected to the third side  2425  by the first end a 1 . The seventh side  2427  is connected to the third side  2425  by the third end a 3 . The seventh side  2427  has a seventh end a 4  opposite to the third end a 3 . If the second end a 2  is connected with the seventh end a 4  by a straight line, the straight line is perpendicular to the second side  2423 . The first side  2421  connecting the second end a 2  with the seventh end a 4  is curved or formed in zigzag patterns. 
     As shown in  FIG. 3 , a pattern of the second electrode  244  is generally a right angled trapezoid with a saw like side. The pattern of the second electrode  244  has the fourth side  2441 , the fifth side  2443  parallel to the X direction, the sixth side  2445 , and a eighth side  2447  opposite to the fifth side  2443  and parallel to the X direction. The fifth side  2443  is connected to the sixth side  2445  by the fourth end b 1 . The eighth side  2447  is connected to the sixth side  2445  by the sixth end b 3 . The eighth side  2447  has a eighth end b 4  opposite to the sixth end b 3 . If the fifth end b 2  is connected with the eighth end b 4  by a straight line, the straight line is perpendicular to the fifth side  2443 . The fourth side  2441  connecting the fifth end b 2  with the eighth end b 4  is curved or formed in zigzag patterns. 
     In each of the plurality of pairs of sensor electrodes  240 , the third side  2425  of the first electrode  242  is adjacent to and parallel to the sixth side  2445  of the second electrode  244 . 
     In each of the plurality of pairs of sensor electrodes  240 , when patterns of the first electrode  242  and the second electrode  244  are designed as right triangles, the two right triangles have the same shape and size. In each of the plurality of pairs of sensor electrodes  240 , when patterns of the first electrode  242  and the second electrode  244  are designed as right angled trapezoids, the two right angled trapezoids have the same shape and size. A width of the first electrode gradually increases, and a width of the second electrode gradually reduces in the Y direction. 
     The at least two wires  28  are used to connect the first electrode  242  with an external circuit. The at least two wires  28  are also used to connect the second electrode  244  with the external circuit. The at least two wires  28  have good conductive properties and flexibility. The at least two wires  28  can be made of metal or carbon nanotube wire. In one embodiment, the at least two wires  28  are made of silver. The number of the at least two wires  28  is equal to the total number of the first electrode  242  and the second electrode  244 . That is, each of the at least two wires  28  is connected to one first electrode  242  or one second electrode  244 . 
     The at least two wires  28  can be located on two opposite sides of the transparent conductive layer  24 , and electrically connected to the first electrode  242  and the second electrode  244 , as shown in  FIGS. 2 and 3 . The at least two wires  28  can be only located on one side of the transparent conductive layer  24 , and electrically connected to the first electrode  242  and the second electrode  244 , as shown in  FIG. 4 . When the at least two wires  28  can be only located on one side of the transparent conductive layer  24 , a wiring space of the at least two wires  28  can be saved. 
     Referring to  FIG. 5 , in the right triangle or the right angled trapezoid, the zigzag patterns includes a plurality of zigzag shapes  15  having the same size. In detail, each of the plurality of zigzag shapes  15  includes a ninth side  152  and a tenth side  154 . The ninth side  152  and the tenth side  154  form an angle designed as α, wherein the α can be in a range from about 164 degrees to about 172 degrees. Therefore, when the touch panel  20  is assembled with a liquid crystal display module, there is minimal or no Moire&#39; effects. A visual identification and operation to the touch panel  20  can be improved. 
     The ninth side  152  has a ninth end  1522  away from the angle α, and the tenth side  154  has a tenth end  1542  away from the angle α. A direction from the ninth end  1522  of the ninth side  152  to the tenth end  1542  of the tenth side  154  is parallel to the Y direction. A distance between the ninth end  1522  of the ninth side  152  and the tenth end  1542  of the tenth side  154  is designed as h, wherein the h can be in a range from about 2 millimeters to about 2.5 millimeters. The angle α has a vertex point  156 . A distance between the vertex point  156  and a line connecting the ninth end  1522  with the tenth end  1542  is related to the ninth side  152 , the tenth side  154  and the angle α. In one embodiment, the distance between the vertex point  156  and a line connecting the ninth end  1522  with the tenth end  1542  is less than or equal to about 160 microns. 
     In one embodiment, in each of the plurality of zigzag shape  15 , the ninth side  152  and the tenth side  154  has the same length. An angle between the ninth side  154  and the Y direction is designed as θ, an angle between the tenth side  154  and the Y direction is also designed as θ, wherein the θ can be in a range from about 4 degrees to about 8 degrees. 
     The transparent conductive layer  24  can be made of transparent conductive materials, for example, indium tin oxide (ITO), antimony tin oxide (ATO), silver thin film, nickel-gold thin film, Polyethylene dioxythiophene two (PEDOT), or carbon nanotube layer. In one embodiment, the transparent conductive layer  24  is made of ITO. A thickness of the transparent conductive layer  24  can be in a range from about 1 micron to about 500 microns. In one embodiment, the thickness of the transparent conductive layer  24  is 125 microns. 
     It is to be understood, a shape of the transparent conductive layer  24  and the substrate  22  can be selected according to a shape of touch area of the touch panel  20 . The shape of touch area of the touch panel  20  can be a wire, triangle or rectangle. In one embodiment, the shape of touch area of the touch panel  20  is a rectangle. 
     Further, in order to prolong operational life span and restrict coupling capacitance of the touch panel  20 , the protective layer  26  is located on the plurality of pairs of sensor electrodes  240  and the transparent conductive layer  24 . The material of the protective layer  26  can, e.g., be selected from a group consisting of silicon nitride, silicon dioxide, benzocyclobutenes (BCB), polyester film, and polyethylene terephthalate. The protective layer  26  can be a slick plastic film and receive a surface hardening treatment to protect the plurality of pairs of sensor electrodes  240  and the transparent conductive layer  24  from being scratched when in use. 
     In one embodiment, the protective layer  26  is silicon dioxide. A hardness and thickness of the protective layer  26  are selected according to practical needs. In one embodiment, the hardness of the protective layer  26  is 7 HB. The protective layer  26  is adhered to the transparent conductive layer  24 , e.g., via an adhesive. 
     The touch panel  20  can further include a shielding layer  25  located on the second surface  222  of the substrate  22 . A material of the shielding layer  25  can be indium tin oxide, antimony tin oxide, carbon nanotube film, and/or another conductive material. In one embodiment, the shielding layer  25  is a carbon nanotube film. The carbon nanotube film includes a plurality of carbon nanotubes, and an orientation of the carbon nanotubes therein may be arbitrarily determined. In one embodiment, the carbon nanotubes in the carbon nanotube film are arranged along a same direction. The carbon nanotube film is connected to ground and acts as a shield, thus enabling the touch panel  20  to operate without interference (such as electromagnetic interference). 
     It is to be understood, the touch panel  20  includes some necessary elements (not illustrated). Materials and structures of the necessary elements can be selected according to conventional touch panel. 
     Referring to  FIG. 6 , a liquid crystal display device  100  of one embodiment includes the touch panel  20 , a liquid crystal display element  30 , a touch panel controller  40 , a central processing unit (CPU)  50 , and a liquid crystal display element controller  60 . The touch panel  20  is connected to the touch panel controller  40  by the at least two wires  28 . The touch panel  20  can be spaced at a distance from the liquid crystal display element  30  or, alternatively, can be installed directly on the liquid crystal display element  30 . The touch panel controller  40 , the CPU  50 , and the liquid crystal display element controller  60  are electrically connected. The CPU  50  is connected to the liquid crystal display element controller  60  to control the liquid crystal display element  30 . 
     When the shielding layer  25  is located on the second surface  222  of the substrate  22 , a passivation layer  104  is located on and in contact with a surface of the shielding layer  25  that faces away from the substrate  22 . The material of the passivation layer  104  can be silicon nitride or silicon dioxide. The passivation layer  104  can be spaced from the liquid crystal display element  30  with a certain distance or, can be directly installed on the liquid crystal display element  30 . When the passivation layer  104  is spaced from the liquid crystal display element  30  with a distance, two or more spacers  108  can be used. Thereby, a gap  106  is provided between the passivation layer  104  and the liquid crystal display element  30 . The passivation layer  104  can protect the shielding layer  25  from chemical or mechanical damage. 
     In operation, the touch panel controller  40  is used to detect coordinates of a touch point by a finger  70  on the touch panel  20 . Then, the touch panel controller  40  sends the coordinates of the touch point to the CPU  50 . The CPU  50  receives and processes the coordinates into a command. Finally, the CPU  50  sends out the command to the liquid crystal display element controller  60 . The liquid crystal display element controller  60  controls the display of the liquid crystal display element  30  accordingly. 
     Referring to  FIG. 7 , another embodiment of the transparent conductive layer  34  is shown where the plurality of pairs of sensor electrodes  240  is arranged adjacent to each other in the X direction and the Y direction. In one embodiment, two pairs of sensor electrodes  240  are arranged adjacent to each other in the X direction, and five pairs of sensor electrodes  240  are arranged adjacent to each other in the Y direction. In one embodiment, the at least two wires  28  is located on two opposite sides of the transparent conductive layer  34 . Each of the plurality of pairs of sensor electrodes  240  is an independent sensor electrode unit. 
     Referring to  FIG. 8 , yet another embodiment of the transparent conductive layer  44  is shown where each of the plurality of pairs of sensor electrodes  240  includes a plurality of first electrodes  242  and a plurality of second electrodes  244  opposite to the plurality of first electrodes  242 . The plurality of first electrodes  242  and the plurality of second electrodes  244  are alternatively stacked and spaced to each other in X direction. In each of the plurality of pairs of sensor electrodes  240 , the plurality of first electrodes  242  is electrically connected to each other, and the plurality of second electrodes  244  is electrically connected to each other. 
     In one embodiment, the plurality of first electrodes  242  is connected to each other by a first connection section  2422  to form an electrode in a comb shape, and the plurality of second electrodes  244  is connected to each other by a second connection section  2442  to form an electrode in the comb shape. It is to be understood, the first connection section  2422  and the second connection section  2442  are formed by etching the transparent conductive layer  44 . The at least two wires  28  is located on two opposite sides of the transparent conductive layer  44 . Each of the plurality of pairs of sensor electrodes  240  is an independent sensor electrode unit. 
     In summary, in the transparent conductive layer  24 ,  34 ,  44 , a leg of the right triangle or the right angled trapezoid extending in a zigzag pattern. The pixels of the liquid crystal display element  30  are arranged in a ribbon shape. Therefore, there is no causing interference of light, and no Moire&#39; effects. A visual identification and operation to the touch panel  20  can be improved. 
     It is to be understood that the above-described embodiment is intended to illustrate rather than limit the disclosure. Variations may be made to the embodiment without departing from the spirit of the disclosure as claimed. The above-described embodiments are intended to illustrate the scope of the disclosure and not restricted to the scope of the disclosure. 
     It is also to be understood that the above description and the claims drawn to a method may include some indication in reference to certain steps. However, the indication used is only to be viewed for identification purposes and not as a suggestion as to an order for the steps.