Patent Publication Number: US-2018046292-A1

Title: Touch sensor-equipped display device

Description:
TECHNICAL FIELD 
     The present invention relates to a touch sensor-equipped display device. 
     BACKGROUND ART 
     Patent Document 1 discloses a touch sensor-equipped display device that includes touch drive electrodes and touch detection electrodes. In this touch sensor-equipped display device, slits are provided in the touch detection electrodes so that the touch detection electrodes become unnoticeable to human eye. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: JP-A-2014-130537 
       
    
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     If, however, the array pattern of subpixels that compose a plurality of display pixels arranged in matrix, and the pattern of the slits in the touch detection electrodes interfere with each other, moire occurs, whereby the display quality of the display device decreases. 
     It is an object of the present invention to provide a touch sensor-equipped display device in which interference between the array pattern of sub pixels that compose display pixels and the pattern of slits in the detection electrodes is suppressed. 
     Means to Solve the Problem 
     A touch sensor-equipped display device in one embodiment of the present invention includes: a display panel including a first substrate, a second substrate opposed to the first substrate, and a display function layer interposed between the first substrate and the second substrate, the display function layer including a plurality of display pixels arranged in matrix; a touch drive electrode that is provided between the first substrate and the second substrate and extends in a first direction; and a touch detection electrode that is provided on a surface of the first substrate on a side opposite to the touch drive electrode, and extends in a second direction that intersects with the first direction at a right angle. In the touch sensor-equipped display device, a plurality of slits each of which is repeatedly bent in a zigzag shape while extending in the second direction are provided in the touch detection electrode so as to be arrayed in the first direction; an arrangement interval “a” for the slits adjacent in the first direction satisfies relationship given as: 
         a=b ×(0.725+ n )×√3÷(2×cos θ)
 
     where “b” represents an arrangement interval for the display pixels adjacent in the first direction, “θ” represents an angle of the slits with respect to the second direction as a reference direction, and “n” represents an integer equal to or greater than 0; and a turnback width of the slits in the zigzag shape is set to (a distance between centers of subpixels adjacent in the first direction among subpixels composing one display pixel)×{a natural number equal to or greater than (the number of colors of the subpixels+1)}. 
     Effect of the Invention 
     With the present invention, the occurrence of moire caused by the interference between the array pattern of subpixels and the pattern of the slits in the touch detection electrode can be suppressed, whereby the display quality of the display device can be improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a cross-sectional configuration of a touch sensor-equipped display device in one embodiment. 
         FIG. 2  is a plan view illustrating the touch sensor-equipped display device in one embodiment. 
         FIG. 3  is a schematic cross-sectional view of a liquid crystal panel with a touch sensor function. 
         FIG. 4  is an enlarged plan view illustrating a plan-view configuration in a display section of an array substrate that composes the liquid crystal panel with a touch sensor function. 
         FIG. 5  is an enlarged plan view illustrating a plan-view configuration in a display section of a CF substrate that composes the liquid crystal panel with a touch sensor function. 
         FIG. 6  is a plan view illustrating an arrangement configuration of touch drive electrodes and touch detection electrodes. 
         FIG. 7  is a diagram for explaining a shape of a slit provided in touch detection electrodes. 
         FIG. 8  illustrates one exemplary arrangement of color filters. 
         FIG. 9  is a diagram obtained by superposing the diagram of the touch detection electrode configuration illustrated in  FIG. 7  on the diagram of color filter arrangement illustrated in  FIG. 8 . 
         FIG. 10A  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 1.000 time the arrangement interval “b” for the display pixels. 
         FIG. 10B  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 1.225 times the arrangement interval “b” for the display pixels. 
         FIG. 10C  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 1.250 times the arrangement interval “b” for the display pixels. 
         FIG. 10D  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 1.500 times the arrangement interval “b” for the display pixels. 
         FIG. 10E  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 1.725 times the arrangement interval “b” for the display pixels. 
         FIG. 10F  is an enlarged view illustrating a part of the display screen when the entirety of the display screen is in a white color display state, in a case where the arrangement interval “a” for the slits is set to 2.000 times the arrangement interval “b” for the display pixels. 
         FIG. 11A  is an enlarged view illustrating a part of the display screen when a black-and-white vertical stripe display is performed, in a case where the arrangement interval “a” for the slits is set to 1.725 times the arrangement interval “b” for the display pixels. 
         FIG. 11B  is an enlarged view illustrating a part of the display screen when a black-and-white chessboard pattern display is performed, in a case where the arrangement interval “a” for the slits is set to 1.725 times the arrangement interval “b” for the display pixels. 
         FIG. 11C  is an enlarged view illustrating a part of the display screen when an RCSB chessboard pattern display is performed, in a case where the arrangement interval “a” for the slits is set to 1.725 times the arrangement interval “b” for the display pixels. 
         FIG. 12A  is a diagram for explaining a method for displaying a black-and-white vertical stripe display. 
         FIG. 12B  is a diagram for explaining a black-and-white chessboard pattern display. 
         FIG. 12C  is a diagram for explaining a black-and-white chessboard pattern display. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     A touch sensor-equipped display device in one embodiment of the present invention includes: a display panel including a first substrate, a second substrate opposed to the first substrate, arid a display function layer interposed between the first substrate and the second substrate, the display function layer including a plurality of display pixels arranged in matrix; a touch drive electrode that is provided between the first substrate and the second substrate and extends in a first direction; and a touch detection electrode that is provided on a surface of the first substrate on a side opposite to the touch drive electrode, and extends in a second direction that intersects with the first direction at a right angle. In the touch sensor-equipped display device, a plurality of slits each of which is repeatedly bent in a zigzag shape while extending in the second direction are provided in the touch detection electrode so as to be arrayed in the first direction; an arrangement interval “a” for the slits adjacent in the first direction satisfies relationship given as: 
         a=b ×(0.725+ n )×√3÷(2×cos θ)
 
     where “b” represents an arrangement interval for the display pixels adjacent in the first direction, “θ” represents an angle of the slits with respect to the second direction as a reference direction, and “n” represents an integer equal to or greater than 0; and a turnback width of the slits in the zigzag shape is set to (a distance between centers of subpixels adjacent in the first direction among subpixels composing one display pixel)×{a natural number equal to or greater than (the number of colors of the subpixels +1)} (the first configuration). 
     With the first configuration, the occurrence of moire caused by the interference between the array pattern of subpixels and the pattern of the slits in the touch detection electrode can be suppressed, whereby the display quality of the display device can be improved. 
     In the first configuration, the slits have a width of 20 μm or less (the second configuration). 
     With the second configuration, the occurrence of moire can be suppressed, whereby the display quality of the display device can be improved. 
     In the first or second configuration, the arrangement interval “a” for the slits is 175 μm or less (the third configuration). 
     With the third configuration, the occurrence of moire can be suppressed, whereby the display quality of the display device can be improved. 
     In any one of the first to third configurations, the angle θ for the slits is in a range of 25° to 45° (the fourth configuration). 
     With the fourth configuration, the occurrence of moire can be suppressed, whereby the display quality of the display device can be improved. 
     Embodiment 
     The following describes embodiments of the present invention in detail, while referring to the drawings. Identical or equivalent parts in the drawings are denoted by the same reference numerals, and the descriptions of the same are not repeated. To make the description easy to understand, in the drawings referred to hereinafter, the configurations are simply illustrated or schematically illustrated, or the illustration of part of constituent members is omitted. Further, the dimension ratios of the constituent members illustrated in the drawings do not necessarily indicate the real dimension ratios. 
       FIG. 1  illustrates a cross-sectional configuration of a touch sensor-equipped display device  10  in one embodiment.  FIG. 2  is a plan view illustrating the touch sensor-equipped display device  10  in one embodiment. The touch sensor-equipped display device  10  includes a liquid crystal panel  11  with a touch sensor function, a backlight device (lighting device)  13 , a bezel  14 , a case  15 , and a cover  16 . Regarding this touch sensor-equipped display device  10 , the side thereof on which the cover  16  is provided is the front side, and the side thereof on which the case  15  is provided is the rear side. 
     The liquid crystal panel  11  with a touch sensor function has a function of displaying an image, and a touch sensor function of detecting a touched position. More specifically, the liquid crystal panel  11  with a touch sensor function has a configuration that includes: a liquid crystal panel (display panel) that includes a pair of substrates and a display function layer provided between the substrates, the display function layer including a plurality of display pixels provided in matrix; touch drive electrodes provided between the pair of substrates of the liquid crystal panel; and touch detection electrodes provided on a front side of the substrate on the front side of the display panel. 
     The backlight device  13  is an external light source that emits light toward the liquid crystal panel  11  with a touch sensor function. 
     The cover  16  is arranged on an outer side of the liquid crystal panel  11  with a touch sensor function so as to protect the liquid crystal panel  11  with a touch sensor function. This cover  16  is made of a material that has excellent impact resistance, for example, tempered glass. The liquid crystal panel  11  with a touch sensor function, and the cover  16 , are bonded and integrated with each other with an approximately transparent adhesive (not shown) being interposed therebetween. 
     The bezel  14  holds the cover  16  and the liquid crystal panel  11  with a touch sensor function together, between the same and the backlight device  13 . The bezel  14  is attached to the case  15 , and the case  15  houses the backlight device  13 . 
       FIG. 3  is a schematic cross-sectional view of the liquid crystal panel  11  with a touch sensor function.  FIG. 4  is an enlarged plan view illustrating a plan-view configuration in a display section of an array substrate that composes the liquid crystal panel  11  with a touch sensor function.  FIG. 5  is an enlarged plan view illustrating a plan-view configuration in a display section of a CF substrate that composes the liquid crystal panel  11  with a touch sensor function. 
     The liquid crystal panel  11  with a touch sensor function includes a pair of substrates  11   a  and  11   b  that are transparent (that have excellent translucency), and a liquid crystal layer  11   c  interposed between the substrates  11   a  and  11   b , as illustrated in  FIG. 3 . The liquid crystal layer  11   c  contains liquid crystal molecules as a substance whose optical properties change in response to the application of an electric field. The substrates  11   a  and  11   b  are bonded with each other with a sealant (not shown) in a state in which a cell gap corresponding to the thickness of the liquid crystal layer  11   c  is maintained therebetween. 
     Each of the substrates  11   a  and  11   b  opposed to each other includes an approximately transparent glass substrate, and has such a configuration that a plurality of films are laminated on the glass substrate by a known photolithography method or the like. Among the substrates  11   a  and  11   b , the CF substrate (first substrate)  11   a  is on the front side, and the array substrate (second substrate)  11   b  is on the rear side (back side). 
     On the inner side surfaces of the substrates  11   a  and  11   b , alignment films  11   d  and  11   e  for aligning the liquid crystal molecules contained in the liquid crystal layer  11   c  are formed, respectively, as illustrated in  FIG. 3 . On the outer side surfaces of the substrates  11   a  and  11   b , polarizing plates  11   f  and  11   g  are laminated, respectively. 
     On the inner side surface of the array substrate  11   b  (the liquid crystal layer  11   c  side, the side opposed to the CF substrate  11   a ), a plurality of thin film transistors (TFTs)  17 , which are switching elements, and a plurality of pixel electrodes  18 , are provided in matrix, as illustrated in  FIGS. 3 and 4 . Gate lines  19  and source lines  20  forming a lattice pattern are arranged so as to enclose these TFTs  17  and pixel electrodes  18 . In other words, at intersections of the gate lines  19  and the source lines  20  forming the lattice pattern, the TFTs  17  and the pixel electrodes  18  are arranged in parallel, so as to be arranged in matrix. 
     The gate lines  19  and the source lines  20  are connected to the gate electrodes and the source electrodes of the TFTs  17 , respectively, and the pixel electrodes  18  are connected to the drain electrodes of the TFTs  17 . Further, each pixel electrode  18  is in a portrait oriented rectangular shape when viewed in a plan view, and is formed with a translucent conductive film made of a material having excellent translucency and conductivity, such as indium tin oxide (ITO) or zinc oxide (ZnO). 
     On the other hand, as illustrated in  FIGS. 3 and 5 , color filters  11   h  are provided in matrix on the CF substrate  11   a , in such a manner that the color portions in colors of red (R), green (G), blue (B) and the like overlap the pixel electrodes  18  on the array substrate  11   b  side when viewed in a plan view. Between the respective color portions that form the color filter  11   h,  a light-shielding layer (black matrix)  11   i  in a lattice pattern for preventing the color mixing is formed. The light-shielding layer  11   i  is arranged so as to overlap the above-described gate lines  19  and the source lines  20  when viewed in a plan view. Over an entire surface of the color filters  11   h  and the light-shielding layer  11   i,  a counter electrode  11   j  is provided, which is opposed to the pixel electrodes  18  on the array substrate  11   b  side. 
     In this liquid crystal panel  11  with a touch sensor function, as illustrated in  FIGS. 3 to 5 , one display pixel as a display unit is composed of a set of the color portions in the three colors of R (red), G (green), and B (blue) and the three pixel electrodes  18  opposed to the color portions, respectively. The display pixel is composed of a red color subpixel having a color portion of R, a green color subpixel having a color portion of G, and a blue color subpixel having a color portion of B. These subpixels of the respective colors are arranged side by side repeatedly in the row direction (X axis direction) on the plate surface of the liquid crystal panel  11 , thereby forming a pixel group, and a multiplicity of such pixel groups are arrayed in the column direction (Y axis direction). In other words, a plurality of the display pixels are arranged in matrix. In the present embodiment, the subpixels are arranged in a so-called stripe array. 
     The following describes the touch sensor function. The liquid crystal panel  11  with a touch sensor function includes touch drive electrodes  61  and touch detection electrodes  62  that compose the touch sensor. As illustrated in  FIG. 3 , the touch drive electrodes  61  are provided on the back side (the liquid crystal layer  11   c  side) of the CF substrate  11   a , and the touch detection electrodes  62  are provided on the front side of the CF substrate  11   a . More specifically, the touch drive electrodes  61  are provided between the CF substrate  11   a  on one hand and the color filters  11   h  and the light-shielding layer  11   i  on the other hand. Further, the touch detection electrodes  62  are provided between the CF substrate  11   a  and the polarizing plate  11   f.  This touch sensor is of the so-called projection type electrostatic capacitance method, and the detection method thereof is of the mutual capacitance type. 
       FIG. 6  is a plan view illustrating the arrangement configuration of the touch drive electrodes  61  and the touch detection electrodes  62 . A plurality of touch drive electrodes  61  extending in the X axis direction are provided so as to be arrayed in the Y axis direction at predetermined intervals. Further, a plurality of touch detection electrodes  62  extending in the Y axis direction are provided so as to be arrayed in the X axis direction at predetermined intervals. The touch drive electrodes  61  and the touch detection electrodes  62  are formed with translucent conductive films made of a material having excellent translucency and conductivity, such as indium tin oxide (ITO) or zinc oxide (ZnO). 
     The following simply explains a method for detecting a touched position. The touch drive electrodes  61  are sequentially scanned so that an input signal is input thereto, and output signals output from the touch detection electrodes  62  are detected. When any area of the surface of the touch sensor-equipped display device  10  is touched, the electrostatic capacitance between the touch drive electrode  61  and the touch detection electrode  62  at the touched position changes. Based on an output signal output from the touch detection electrode  62 , the position where the electrostatic capacitance has changed is detected, and the detected position is identified as the touched position. 
     Between the plurality of the touch detection electrodes  62  provided on the front side of the CF substrate  11   a , the dummy electrodes  63  are provided. In other words, in each space between adjacent ones of the plurality of touch detection electrodes  62  arrayed in the X axis direction at predetermined intervals, a plurality of dummy electrodes  63  extending in the Y axis direction are provided. 
     The dummy electrodes  63  are provided for the purpose of preventing the light transmission rate and the like from becoming different between the positions where the touch detection electrodes  62  are provided and the positions where they are not provided, on the front side of the CF substrate  11   a . The dummy electrodes  63 , therefore, are formed with conductive films made of the same material as that of the touch detection electrodes  62 , that is, a material having excellent translucency, such as ITO or ZnO. It should be noted that the dummy electrodes  63  are not connected with other lines or electrodes, and are in an electrically floating state. 
     The touch detection electrodes  62  and the dummy electrodes  63  have predetermined refractive indices, though they are transparent. In the touch detection electrodes  62  and the dummy electrodes  63 , therefore, a plurality of slits are provided so as to make the touch detection electrodes  62  and the dummy electrodes  63  unnoticeable when the touch sensor-equipped liquid crystal display device  10  is viewed. 
       FIG. 7  is a diagram for explaining the shape of slits provided in the touch detection electrodes  62 . It should be noted that slits in the identical shape are provided in the dummy electrodes  63 , though the illustration of the same is omitted. 
     The touch detection electrode  62  is composed of a plurality of electrode portions  621  formed with translucent conductive films, and a plurality of slits  622  provided between the plurality of electrode portions  621 . Each slit  622  is repeatedly bent in a zigzag shape, while extending in the Y axis direction as an entire slit. In other words, each slit  622  is composed of first direction linear portions  622   a  extending in a first direction, and second direction linear portions  622   b  extending in a second direction that is different from the first direction. Here, the first direction linear portions  622   a  and the second direction linear portions  622   b  have the same width in the X axis direction, and the same length in the Y axis direction. 
     In the present embodiment, an arrangement interval “a” for the slits  622  adjacent in the X axis direction in a plan view satisfies the relationship given as the following expression (1): 
         a=b ×(0.725+ n )×√3÷(2×cos θ)   (1)
 
     where “b” represents an arrangement interval for a plurality of the display pixels adjacent in the X axis direction in a plan view, “θ” represents an angle of the slit  622  with respect to the Y axis direction as a reference direction, and “n” represents an integer equal to or greater than 0 (n=0, 1, 2, . . . ). 
     Further, the turnback width “c” of the slit  622  in the zigzag shape is set to (the distance between the centers of the subpixels adjacent in the X axis direction among the plurality of subpixels composing one display pixel)×{a natural number equal to or greater than (the number of colors of the subpixels+1)}. The turnback width “c” of the slit  622  is a width of the first direction linear portion  622   a  (or the second direction linear portion  622   b ) in the X axis direction. For example, in a case where the subpixels correspond to the three colors of R (red), G (green), and B (blue), the turnback width “c” of the slit  622  is assumed to be {(the distance between the centers of the subpixels)×(a natural number equal to or greater than 4)}. In the present embodiment, the turnback width “c” of the slit  622  is set to {(the distance between the centers of the subpixels)×4}. 
     It is preferable that the width “d” of the slit  622  in the X axis direction is 20 μm or less. Further, it is preferable that the arrangement interval “a” of the slits  622  adjacent in the X axis direction is 175 μm or less. 
     The angle θ of the slit  622  is preferably 25° to 45°, and is set to 30° in the present embodiment. 
       FIG. 8  illustrates one exemplary arrangement of color filters  11   h.  Further,  FIG. 9  is a diagram obtained by superposing the diagram of a configuration of the touch detection electrode  62  illustrated in  FIG. 7 , on the diagram of color filter arrangement illustrated in  FIG. 8 .  FIG. 9  illustrates the arrangement interval “a” for the slits  622 , and the arrangement interval “b” for the display pixels as well. It should be noted that the arrangement interval “a” for the slits  622  is the arrangement interval in a case where n=1 and θ=30° in the expression (1), that is, 1.725 times the arrangement interval “b” for the display pixels. 
       FIGS. 10A to 10F  illustrate differences in appearance of the display screen when the arrangement interval “a” for the slits  622  is varied with respect to the arrangement interval “b” for the display pixels. Each of  FIGS. 10A to 10F  is an enlarged view illustrating a part of the display screen when white color display is performed in the entire display screen. In  FIGS. 10A to 10F , the arrangement interval “a” for the slits  622  is set to 1.000 time, 1.225 times, 1.250 times, 1.500 times, 1.725 times, and 2.000 times the arrangement interval “b” for the display pixels, respectively. 
     In the case where the arrangement interval “a” for the slits  622  is set to 1.000 time the arrangement interval “b” for the display pixels, wide horizontal lines are visible as moire, as illustrated in  FIG. 10A . In the case where the arrangement interval “a” for the slits  622  is set to 1.225 times or 1.250 times the arrangement interval “b” for the display pixels, thin diagonal lines are visible as moire, as illustrated in  FIG. 10B  or  FIG. 10C . In the case where the arrangement interval “a” for the slits  622  is set to 1.500 times or 2.000 times the arrangement interval “b” for the display pixels, wide horizontal lines are visible as moire, as illustrated in  FIG. 10D  or  FIG. 10F . 
     On the other hand, in the case where the arrangement interval “a” for the slits  622  is set to 1.725 times the arrangement interval “b” for the display pixels so as to satisfy the relationship given as the expression (1), clear moire is not seen as illustrated in  FIG. 10E . 
       FIG. 10E  illustrates the appearance of the display screen when the arrangement interval “a” for the slits  622  is set so as to satisfy the expression (1) and white color display is performed in the entire display screen. The following also describes the appearance of the display screen in a case where the arrangement interval “a” for the slits  622  is set so as to satisfy the following expression (1), and display other than the white color display is performed. 
       FIGS. 11A to 11C  are enlarged views illustrating a part of the display screen in cases where the arrangement interval “a” for the slits  622  is set so as to satisfy the expression (1) and displays illustrated in  FIGS. 17A to 17C  are performed. Here, also, the arrangement interval “a” for the slits  622  is set to the interval in the case where n=1 and θ=30° in the expression (1), that is, set to 1.725 times the arrangement interval “b” for the display pixels. 
       FIG. 11A  illustrates a display screen in a case where a black-and-white vertical stripe display is performed (corresponding to  FIG. 12A ),  FIG. 11B  illustrates a display screen in a case where a black-and-white chessboard pattern display is performed (corresponding to  FIG. 12B ), and  FIG. 11C  illustrates a display screen in a case where an RGB chessboard pattern display is performed (corresponding to  FIG. 12C ). In a case where the arrangement interval “a” for the slits  622  is set so as to satisfy the expression (1), clear moire is not seen, in any one of the case where the black-and-white vertical stripe display ( FIG. 11A ) is performed, the case where the black-and-white chessboard pattern display ( FIG. 11B ) is performed, and the case where the RGB chessboard pattern display ( FIG. 11C ) is performed, as is the case where white color display is performed in the entire display screen ( FIG. 10E ). 
     The present invention is not limited to the above-described embodiment. For example, the foregoing description refers to a liquid crystal panel as an exemplary display panel in which a display function layer including a plurality of display pixels arranged in matrix is provided between a pair of substrates, but the display panel may be another display panel such as an organic electroluminescence (EL) panel including organic EL elements. 
         a=b ×(0.725+ n )×√3÷(2×cos θ)
 
     In the foregoing description, the colors of the subpixels are three colors of R (red), G (green), and B (blue), but the colors may be four colors of R (red), G (green), B (blue), and Y (yellow), or alternatively, five or more colors. 
     The touch sensor-equipped display device in the present embodiment is used in various types of electronic devices such as mobile phones (including smartphones), notebook computers (including tablet-type notebook computers), portable information terminals (including electronic books and PDAs), digital photoframes, and portable game machines. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
           10  . . . touch sensor-equipped display device 
           11  . . . touch sensor-equipped liquid crystal panel 
           11   a  . . . CF substrate 
           11   b  . . . array substrate 
           61  . . . touch drive electrode 
           62  . . . touch detection electrode 
           622  . . . slit