Abstract:
A display device with touch panel includes a display panel having a display area in which pixels are arranged in a matrix form and displaying an image by outputting lights corresponding to gray levels with respect to each pixel, and a touch panel electrode as one electrode of a set of electrodes forming capacitance for sensing contact in an area superimposed on the display area, extending in one direction, including a plurality of linear transparent conducting materials arranged in parallel, and having a periodically changing line width.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese application JP2013-133226 filed on Jun. 25, 2013, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to a display device with touch panel. 
         [0004]    2. Description of the Related Art 
         [0005]    Touch panels as input devices provided on display screens of information communication terminals including computers have been widely used. 
         [0006]    The touch panels are input devices that allow processors to perform processing by recognizing coordinates on panels touched by users using fingers or the like. For the touch panels, a resistive-film system that detects changes in resistance of a touched part, an optical sensor system that detects changes in amounts of light of a part blocked by touch, a capacitance coupling system that detects changes in capacitance, etc. have been known. The capacitance coupling system has been widely used because of the higher transmittance of the panel without reduction in the display image quality, no contact with other electrodes and the higher durability, or the like. 
         [0007]    Recently, in response to requests for downsizing and thinning with respect to information communication terminals, thinner liquid crystal display devices with touch panel have been demanded. JP 2009-244958 A has disclosed a thinner liquid crystal display device with touch panel by using common electrodes of the liquid crystal display device as drive electrodes of the touch panel in the IPS (In-Plane Switching) liquid crystal display device in which both pixel electrodes and the common electrodes are provided on a TFT (Thin Film Transistor) substrate. 
       SUMMARY OF THE INVENTION 
       [0008]    In a capacitance touch panel of a display device with touch panel, a plurality of electrodes of a transparent conducting material such as ITO (Indium Tin Oxide) and extending in one direction in parallel on a display area for detection of a touch position are formed. The refractive index of light in the area with the electrodes formed therein is different from the refractive index in an area without the electrodes, and thus, the parts with the electrodes formed therein may be visually recognized as streaky patterns due to reflection of sunlight or the like, for example. 
         [0009]    The invention has been achieved in view of the above described situations, and an object of the invention is to provide a display device with touch panel for an observer hard to recognize electrode shapes even when outside light is reflected by a touch panel surface. 
         [0010]    A display device with touch panel of the invention is a display device with touch panel including a display panel having a display area in which pixels are arranged in a matrix form and displaying an image by outputting lights corresponding to gray levels with respect to each pixel, and a touch panel electrode as one electrode of a set of electrodes forming capacitance for sensing contact in an area superimposed on the display area, extending in one direction, including a plurality of linear transparent conducting materials arranged in parallel, and having a periodically changing line width. In the display device with touch panel of the invention, the line width periodically changes in a range from 10 to 30 μm. 
         [0011]    Further, in the display device with touch panel of the invention, a shape of the touch panel electrode may be a beaded shape in which a plurality of circular shapes are provided with shifts of distances less than diameters of the circular shapes in the one direction. 
         [0012]    Furthermore, in the display device with touch panel of the invention, an area in which the touch panel electrodes are arranged in parallel may have touch panel electrode areas in which the touch panel electrodes are arranged in parallel at equal intervals, and dummy electrode areas as areas spaced at larger intervals than the equal intervals between the electrode areas, extending in the one direction, and including dummy electrodes of a plurality of linear transparent conducting materials arranged in parallel, and the dummy electrodes may have the same shapes as those of the touch panel electrodes and are arranged in parallel at the equal intervals. 
         [0013]    Further, in the display device with touch panel of the invention, the dummy electrodes may be electrically floating or grounded. 
         [0014]    Furthermore, in the display device with touch panel of the invention, an arrangement pitch of the touch panel electrodes arranged in parallel may be from 30 to 50 μm. 
         [0015]    Further, in the display device with touch panel of the invention, the pixels may be provided in gaps between the touch panel electrodes so that lights of blue pixels may be output in a plan view. 
         [0016]    Furthermore, in the display device with touch panel of the invention, the touch panel electrodes may be drive electrodes to which drive pulse is applied and detection electrodes that form capacitance. 
         [0017]    Further, in the display device with touch panel of the invention, the display device may be a liquid crystal display device that controls an amount of transmission light by controlling alignment of a liquid crystal composition using an electric field formed between pixel electrodes and a common electrode, and the common electrode may be divided into a plurality of parts and at least part thereof may be an other electrode of the set of electrodes forming the capacitance for sensing contact. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  shows a liquid crystal display device with touch panel according to one embodiment of the invention. 
           [0019]      FIG. 2  is a block diagram showing a control configuration of a liquid crystal display panel with touch panel in  FIG. 1 . 
           [0020]      FIG. 3  shows an arrangement of electrodes controlled by a touch panel control unit in  FIG. 2 . 
           [0021]      FIG. 4  is a sectional view along IV-IV line in  FIG. 3 . 
           [0022]      FIG. 5  is an enlarged view of detection areas and dummy areas alternately arranged on a color filter board. 
           [0023]      FIG. 6  is a sectional view for explanation of a cause of generation of interference fringes (moire) in the display device with touch panel. 
           [0024]      FIG. 7  is an enlarged view of two detection lines and color filters that output lights through a gap between the lines. 
           [0025]      FIG. 8  is a sectional view for explanation of a cause of generation of streaky bright parts in the display device with touch panel. 
           [0026]      FIG. 9  is a plan view for explanation of the cause of generation of the streaky bright parts in the display device with touch panel. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    As below, embodiments of the invention will be explained with reference to the drawings. Note that, in the drawings, the same or equal elements have the same signs and the duplicated explanation will be omitted. 
         [0028]      FIG. 1  shows a liquid crystal display device with touch panel  100  according to an embodiment of the invention. As shown in the drawing, the liquid crystal display device with touch panel  100  includes a liquid crystal display panel with touch panel  200 , and an upper frame  101  and a lower frame  102  that secure to sandwich the liquid crystal display panel with touch panel  200 . 
         [0029]      FIG. 2  is a block diagram showing a control configuration of the liquid crystal display panel with touch panel  200  in  FIG. 1 . As shown in the drawing, the liquid crystal display panel with touch panel  200  is controlled by a display control unit  252  that controls a liquid crystal display function of performing screen display, a touch panel control unit  254  that controls a touch panel function of detecting a touch position on a screen, and a system control unit  256  that performs integrated control of the display control unit  252  and the touch panel control unit  254 . The liquid crystal display device with touch panel  100  also has the display control unit  252 , the touch panel control unit  254 , and the system control unit  256  to control. 
         [0030]      FIG. 3  shows an arrangement of electrodes controlled by the touch panel control unit  254  in  FIG. 2 . Common electrodes used for liquid crystal display include drive electrodes  213  having strip shapes extending along short sides of a display area, to which voltages are applied from the touch panel control unit  254 , and non-drive electrodes  215  as other electrodes than the drive electrodes  213 , having strip shapes extending along the short sides of the display area, and they are arranged to cover the display area. 
         [0031]    On the other hand, in another layer than the layer with the common electrodes arranged therein, a plurality of detection areas  230  arranged in parallel along the short sides of the display area, in which a plurality of detection lines  231  to be described later extending along long sides of the display area are provided, and dummy areas  240  provided between the respective detection areas  230 , in which dummy conductive lines  241  to be described later similar to the detection lines  231  are provided like the detection areas  230  are formed. Further, signals detected by the plurality of detection lines  231  are input to the touch panel control unit  254  with respect to each detection area  230 . The dummy conductive lines  241  within the dummy areas  240  may be electrically floating or grounded. When the lines are floating, the lines have functions as auxiliary capacitance at touch detection. Note that, in the drawing, for explanation, the number of detection areas  230  etc. are omitted, however, it is desirable that the pitch of the arrangement of the detection areas  230  is about 5 mm, the width of the detection areas  230  is about 700 μm, and the dummy areas  240  are arranged to fill the spaces between the detection areas  230 . 
         [0032]      FIG. 4  schematically shows a sectional view along IV-IV line of  FIG. 3 . As shown in the drawing, the liquid crystal display panel with touch panel  200  includes a TFT board  210  on which thin film transistors (TFTs) (not shown) are formed and circuits for controlling alignment of liquid crystal are formed with respect to each pixel, a color filter board  220  that outputs incident lights as lights having wavelengths of the respective RGB colors with respect to each pixel by color filters (not shown), and a liquid crystal layer  227  containing a liquid crystal composition sealed by a sealing agent  228  between the boards. 
         [0033]    Here, in the TFT board  210 , as shown in  FIG. 4 , the drive electrodes  213  and the non-drive electrodes  215  (see  FIG. 3 ), which are functioning as the common electrodes, and the pixel electrodes  212  in liquid crystal display are formed on a glass substrate  211 , and, in the color filter board  220 , the detection areas  230  and the dummy areas  240  are formed on a glass substrate  221 . 
         [0034]      FIG. 5  is an enlarged view of the detection areas  230  and the dummy areas  240  alternately arranged on the glass substrate  221  of the color filter board  220 . As shown in the drawing, the detection areas  230  and the dummy areas  240  include the plurality of detection lines  231  and the plurality of dummy conductive lines  241 , respectively. The respective detection lines  231  and dummy conductive lines  241  have beaded shapes in which a plurality of circular shapes are provided with shifts of distances less than their diameters, and thereby, the respective detection lines  231  and the respective dummy conductive lines  241  extend while periodically changing line widths. In the embodiment, the example in which the detection areas  230  each including the four detection lines  231  and the dummy areas  240  each including the four dummy conductive lines  241  are alternately arranged is shown, and intervals between the respective detection lines  231 , intervals between the respective dummy conductive lines  241 , and intervals between the detection areas  230  and the dummy areas  240  are equal. Note that the intervals between the respective detection lines  231 , the intervals between the respective dummy conductive lines  241 , and the intervals between the detection areas  230  and the dummy areas  240  may be arbitrarily determined, the intervals between the respective detection lines  231  and the intervals between the respective dummy conductive lines  241  may be different, and may be different from the intervals of the detection areas  230  and the dummy areas  240 . 
         [0035]    In the drawing, the shapes of the detection lines  231  and the dummy conductive lines  241  are the above described beaded shapes, however, may be shapes defined by curved lines, shapes defined by linear lines, or shapes using both of the lines as long as the shapes may have periodically changing line widths. 
         [0036]    The shapes have periodically changing line widths, and thereby, even when the outside light is reflected by the touch panel surface, visual recognition of the electrode shapes of the detection lines  231  and the dummy conductive lines  241  may be made harder. Particularly, the line widths are periodically changed in the range from 10 to 30 μm, and thereby, the shapes are not substantially visually sensed by the observer. Here, it is desirable that the pitch of the arrangement of the detection lines  231  or the dummy conductive lines  241  is from 30 to 50 μm. Further, with the shapes, for example, it is not necessary to provide an optical sheet having a function of homogenizing the reflection light of the outside light or the like. 
         [0037]      FIG. 6  is a sectional view for explanation of a cause of generation of interference fringes (moire) in the display device with touch panel. In  FIG. 6 , for explanation, the detection lines  231  and the dummy conductive lines  241  formed on the glass substrate  221  of the color filter board  220  and a color filter layer  224  in which R (red) G (green) B (blue) color filters formed at the TFT board  210  side of the glass substrate  221  are arranged are shown. As shown in the drawing, in bright lights output through the gaps between the detection lines  231  and the dummy conductive lines  241 , when the RGB lights periodically change while pluralities of them are respectively continuing, the difference between the period and the period of the RGB arrangement of the color filters is considered to be a cause of generation of interference fringes. 
         [0038]      FIG. 7  is an enlarged view of the two detection lines  231  and the color filters that output lights through the gap between the lines. As shown in the drawing, the line widths of the detection lines  231  and the dummy conductive lines  241  periodically change and there are parts in which the lights output from the gap between the two detection lines  231  are lights, not monochromatic, but in a plurality of colors of B-color and R-color, for example, and thereby, generation of interference fringes may be prevented. Further, by the periodic changes of the line widths, the periodicity causing interference fringes is changed, and thereby, the generation of interference fringes may be prevented. Furthermore, the generation of interference fringes may be prevented, and thereby, for example, it is not necessary to provide an optical sheet having a function of making recognition of interference fringes harder or the like. 
         [0039]    Note that the above described cause of interference fringes is just an example, and, even when there is another cause, the line widths of the detection lines  231  and the dummy conductive lines  241  are periodically changed, and thereby, in many cases where the periodicity causing interference fringes is hindered, the generation of interference fringes may be suppressed according to the embodiment. 
         [0040]      FIGS. 8 and 9  are respectively a sectional view and a plan view for explanation of a cause of generation of streaky bright parts in the display device with touch panel. In  FIG. 8 , like in  FIG. 6 , the detection lines  231  and the dummy conductive lines  241  and the color filter layer  224  in which RGB color filters are arranged are shown. As shown in the drawing, for example, at monochromatic emission of G-color light, there are lights L 1  visually sensed via the detection lines  231  and the dummy conductive lines  241  and lights L 2  passing through the gaps between the detection lines  231  and the dummy conductive lines  241 , and thereby, only the parts of the lights L 2  are bright and highly visible.  FIG. 9  shows the planar view of  FIG. 8 , and shows the cause of generation of streaky bright parts using shapes of detection lines of a display device with touch panel in related art. As shown in the drawing, at the monochromatic emission of G-color light, the G-color light from the gap  301  of the detection lines  231  is visually sensed particularly brightly, and recognized as a streaky brightness part compared to the other G-colors visually recognized via the detection lines  231  and the dummy conductive lines  241 . Regarding the visual defect, in the embodiment, as shown in  FIG. 7 , the line widths of the detection lines  231  and the dummy conductive lines  241  periodically change, and there are parts in which the lights output from the gaps between the detection lines  231  and the dummy conductive lines  241  are lights, not monochromatic, but in a plurality of colors of B-color and R-color, for example. Accordingly, generation of those streaky bright parts may be suppressed. Further, thereby, for example, it is not necessary to provide an optical sheet having a function of making recognition of streaky bright parts harder or the like. 
         [0041]    Note that, to suppress the generation of the streaky bright parts, in addition to the above described embodiment, the color of the pixels provided in the gaps between the detection lines  231  and the dummy conductive lines  241  may be set to a color with brightness relatively hard to be visually sensed. The color with brightness hard to be visually sensed is specifically B among RGB. The B-color pixels are provided in the gaps between the detection lines  231  and the dummy conductive lines  241  in the plan view, and thereby, the generation of the streaky bright parts may be further suppressed. 
         [0042]    Note that, in the embodiment, the shapes having periodically changing line widths are applied to the detection electrodes at the side closer to the observer&#39;s side, however, the shapes may be applied to electrodes formed at the farther sides from the observer&#39;s side or may be applied to either of the detection electrodes or the drive electrodes. 
         [0043]    Further, in the display device of the embodiment, the RGB pixels are provided, however, the display device may have pixels of different colors such as RGBW (white). 
         [0044]    Furthermore, in the embodiment, the touch panel containing display device combined with the IPS liquid crystal display device is shown, however, the embodiment may be applied to a separate touch panel device for attachment to a display surface of a display device such as a liquid crystal display device or an organic EL display device, or may be applied to another touch panel containing display device. 
         [0045]    While there have been described what are at present considered to be certain embodiments of the invention, it will be understood that various modifications may be made thereto, and it is intended that the appended claim cover all such modifications as fall within the true spirit and scope of the invention.