The present invention relates to a touch-panel-equipped display device.
JP-A-2015-122057 discloses a touch screen panel integrated display device that includes a panel that serves as both of a display and a touch screen. The panel includes an upper substrate provided with color filters, a lower substrate in which a plurality of pixels are formed, and a liquid crystal layer provided between the upper substrate and the lower substrate. Each pixel of the substrate is provided with a pixel electrode, and a transistor connected to the pixel electrode. Further, on the lower substrate, a plurality of electrodes are arranged so as to be opposed to the pixel electrodes, to be separated from the pixel electrodes. The plurality of electrodes function as common electrodes that form lateral electric fields (horizontal electric fields) between the same and the pixel electrodes in the display driving mode, and function as touch electrodes that form electrostatic capacitors between the same and a finger or the like in the touch driving mode. Each of the plurality of electrodes is connected to at least one signal line, approximately parallel with data lines, so that a touch driving signal or a common voltage signal is supplied thereto via the signal line.
In the case of JP-A-2015-122057, the liquid crystal layer is provided between the upper substrate to be touched by a user's finger, and the electrodes of the lower substrate that detect the touch. If a change occurring to the electrostatic capacitance when the upper substrate is touched is small, a change in the liquid crystal capacitance caused by an image displaying operation makes it difficult to detect the change in the electrostatic capacitance when the user's finger is touched with the upper substrate. Further, if the whole of panel is warped when the upper substrate is touched, the distances between the electrodes of the lower substrate and other elements change, which causes the capacitances at the electrodes to change. In this case, changes in the capacitances caused by the warp of the whole of panel make it difficult to detect the changes in the electrostatic capacitances when the upper substrate is touched.
It is an object of the present invention to provide a touch-panel-equipped display device in which the touch detection sensitivity can be improved.
A touch-panel-equipped display device in one embodiment of the present invention is a touch-panel-equipped display device that includes an active matrix substrate, a counter substrate provided so as to be opposed to the active matrix substrate, and a liquid crystal layer provided between the active matrix substrate and the counter substrate, and that has a touch surface on an active matrix substrate side. The active matrix substrate includes a plurality of pixel electrodes, a plurality of counter electrodes to detect a touch with respect to the touch surface and make capacitances between the same and the pixel electrodes, and a plurality of signal lines connected with the counter electrodes, on a liquid crystal layer side of the substrate. The counter substrate includes, on a surface thereof on a side opposite to the liquid crystal layer side, shield electrodes that are arranged so as to overlap with the counter electrodes when viewed in a plan view and have a reference potential. The pixel electrodes and the counter electrodes are arranged so as to overlap with each other when viewed in a plan view, and the counter electrodes are arranged at positions closer to the substrate than the pixel electrodes are.
With the present invention, the touch detection sensitivity can be improved.
A touch-panel-equipped display device in one embodiment of the present invention is a touch-panel-equipped display device that includes an active matrix substrate, a counter substrate provided so as to be opposed to the active matrix substrate, and a liquid crystal layer provided between the active matrix substrate and the counter substrate, and that has a touch surface on an active matrix substrate side. The active matrix substrate includes a plurality of pixel electrodes, a plurality of counter electrodes to detect a touch with respect to the touch surface and make capacitances between the same and the pixel electrodes, and a plurality of signal lines connected with the counter electrodes, on a liquid crystal layer side of the substrate. The counter substrate includes, on a surface thereof on a side opposite to the liquid crystal layer side, shield electrodes that are arranged so as to overlap with the counter electrodes when viewed in a plan view and have a reference potential. The pixel electrodes and the counter electrodes are arranged so as to overlap with each other when viewed in a plan view, and the counter electrodes are arranged at positions closer to the substrate than the pixel electrodes are (the first configuration).
According to the first configuration, the touch-panel-equipped display device has a touch surface on the active matrix substrate side, and there are provided a plurality of pixel electrodes, a plurality of counter electrodes, and a plurality of signal lines on the liquid crystal layer side of the active matrix substrate. The counter electrodes are used in an image displaying operation, detect a touch with respect to the touch surface, and are arranged at positions closer to the substrate than the pixel electrodes are. In other words, the liquid crystal layer is not provided between the touch surface and the counter electrodes. Accordingly, even if an image displaying operation causes a capacitance change to occur in the liquid crystal layer, the detection is not affected by the change in the liquid crystal capacitance, as compared with a case where the liquid crystal layer is between the touch surface and the counter electrodes. This therefore makes it possible to detect a small capacitance change when a touch is made. Further, on the surface on the liquid crystal layer side of the counter substrate, the shield electrodes having a reference potential are provided. For this reason, even if the touch-panel-equipped display device is warped when a user's finger or the like touches the device, a change in the electrostatic capacitances between the counter electrodes and the members provided on the back surface side of the counter substrate can be reduced, which therefore makes it possible to detect a capacitance change when the touch surface is touched.
The first configuration may be further characterized in that the active matrix substrate further includes a plurality of gate lines, and a plurality of data lines that intersect with the gate lines, on the liquid crystal layer side of the substrate; the counter electrodes are arranged so as to be arrayed in a gate line extending direction and a data line extending direction; and at least one data line is arranged between adjacent ones of the counter electrodes that are adjacent in the gate line extending direction when viewed in a plan view (the second configuration).
According to the second configuration, at least one data line is arranged between adjacent ones of the counter electrodes that are adjacent in the gate line extending direction. This makes it unlikely that external electric fields from the touch surface side would affect the liquid crystal layer, which results in that alignment defects in the liquid crystal layer can be reduced.
The first or second configuration may be further characterized in that the active matrix substrate further includes a plurality of gate lines, and a plurality of data lines that intersect with the gate lines, on the liquid crystal layer side of the substrate; the counter electrodes are arranged so as to be arrayed in a gate line extending direction and a data line extending direction; and at least one gate line is arranged between adjacent ones of the counter electrodes that are adjacent in the data line extending direction when viewed in a plan view (the third configuration).
According to the third configuration, at least one gate line is arranged between adjacent ones of the counter electrodes that are adjacent in the data line extending direction. This makes it unlikely that external electric fields from the touch surface side would affect the liquid crystal layer, which results in that alignment defects in the liquid crystal layer can be reduced.
Any one of the first to third configurations may be further characterized in that the signal lines and the pixel electrodes are arranged in different layers (the fourth configuration).
With the fourth configuration, alignment defects in the liquid crystal layer caused by electrostatic capacitances between the pixel electrodes and the signal lines can be reduced, as compared with a case where the pixel electrodes and the signal lines are arranged in the same layer.
Any one of the first to fourth configurations may be further characterized in that the active matrix substrate further includes: a first insulating film that is arranged between the counter electrodes and the pixel electrodes; a second insulating film that is arranged on a side opposite to the counter electrodes with respect to the pixel electrodes, and covers the pixel electrodes; and a transparent electrode that is arranged so as to overlap with the pixel electrodes with the second insulating film being interposed therebetween, and is electrically connected with the counter electrodes (the fifth configuration).
According to the fifth configuration, the pixel electrodes are arranged between the counter electrodes and the transparent electrode, with the first insulating film being interposed between the pixel electrodes and the counter electrodes, and the second insulating film being interposed between the pixel electrodes and the transparent electrode; and the transparent electrode is electrically connected with the counter electrodes. This makes it possible to increase pixel capacitances, thereby improving the display quality, as compared with a case where only the counter electrodes are provided.
Any one of the first to fifth configurations may be further characterized in that the active matrix substrate further includes a plurality of switching elements each of which includes a source electrode, a drain electrode, a semiconductor film, and a gate electrode; and the gate electrode is provided on the liquid crystal layer side with respect to the semiconductor film (the sixth configuration).
According to the sixth configuration, the gate electrodes of the switching elements are provided on the liquid crystal layer side with respect to the semiconductor films. In other words, the switching element has a top gate structure with respect to the substrate. This makes it unlikely that light from the back side of the touch-panel-equipped display device would enter the channel area of the switching element, which makes it unnecessary to additionally provide a light-shielding film.
Any one of the first to fifth configurations may be further characterized in that the active matrix substrate further includes a plurality of switching elements each of which includes a source electrode, a drain electrode, a semiconductor film, and a gate electrode, and the gate electrode is provided on the substrate side with respect to the semiconductor film (the seventh configuration).
According to the seventh configuration, the gate electrodes are provided on the substrate side with respect to the semiconductor film. This therefore makes it possible to block light from the substrate side that would enter the channel area of the switching element.
Any one of the first to seventh configurations may be further characterized in that the active matrix substrate further includes a light-shielding section between the pixel electrodes and the substrate (the eighth configuration).
With the eighth configuration, external light from the surface of the substrate on a side opposite to the liquid crystal layer can be blocked.
The eighth configuration may be further characterized in that the light-shielding section is arranged at a position that does not overlap with the pixel electrodes (the ninth configuration).
With the ninth configuration, the light-shielding section does not overlap with the pixel electrodes, whereby the aperture ratio of the pixels can be improved.
The following description 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 shown or schematically shown, or the illustration of a part of constituent members is omitted. Further, the dimension ratios of the constituent members shown in the drawings do not necessarily indicate the real dimension ratios.
The touch-panel-equipped display device 10 has a function of displaying an image and has a function of detecting a position (touch position) at which a finger of a user or the like touches on the displayed image, that is, on a surface on the polarizing plate 4A provided in the active matrix substrate 1 side.
Besides, this touch-panel-equipped display device 10 is a so-called in-cell type touch panel display device in which elements necessary for detecting a touch position are provided on the active matrix substrate 1. Further, in the touch-panel-equipped display device 10, the method for driving liquid crystal molecules included in the liquid crystal layer 3 is the horizontal electric field driving method. To realize the horizontal electric field driving method, pixel electrodes and counter electrodes (common electrodes) for forming electric fields are formed on the active matrix substrate 1.
In each pixel, a pixel electrode and a switching element are arranged. For forming the switching element, for example, a thin film transistor is used.
The active matrix substrate 1 includes a source driver 30 and a gate driver 40 in an area (frame area) outside the display area R. The source driver 30 is connected with each data line 22, and supplies voltage signals to the data lines 22 in accordance with image data, respectively. The gate driver 40 is connected with each gate line 21, and sequentially supplies a voltage signal to the gate lines 21 so as to scan the gate lines 21.
Further, the active matrix substrate 1 is further provided with a controller 50. The controller 50 performs a controlling operation for detecting a touch position.
The controller 50 and the counter electrodes 23 are connected by signal lines 24 extending in the Y axis direction. In other words, the same number of signal lines 24 as the number of the touch detection electrodes 23 are formed on the active matrix substrate 1.
The counter electrodes 23 in pairs with the pixel electrodes are used during the controlling operation for displaying an image, and are also used during the controlling operation for detecting a touch position.
Regarding the counter electrodes 23, parasitic capacitances occur between the same and adjacent ones of the counter electrodes 23, other elements, or the like when nothing is in contact with the touch surface. When a human finger or the like touches the display screen of the display device 10, capacitors occur between the same and the human finger or the like, and thereby electrostatic capacitances increase. During the control for touch position detection, the controller 50 supplies a touch driving signal for detecting a touch position, to the counter electrodes 23 through the signal lines 24, and receives a touch detection signal through the signal lines 24. By doing so, the controller 50 detects changes in the electrostatic capacitances at the positions of the counter electrodes 23, and detects a touch position. Further, a predetermined voltage signal is supplied to the signal line 24 by the controller 50 during the controlling operation for displaying an image, and supplies the predetermined voltage signal to the counter electrode 23. In other words, the signal line 24 functions as a line for transmission/reception of the touch driving signal and the touch detection signal, and the counter electrodes 23 function as a common electrode that makes a horizontal electric field between itself and the pixel electrodes.
The pixel electrodes 25 are provided in pixel areas defined by the gate lines 21 and the data lines 22. The gate electrode of the above-described TFT is connected to the gate line 21, and either of the source electrode and the drain electrode is connected with the data line 22, while the other is connected with the pixel electrode 25.
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The semiconductor film 70b is arranged so as to overlap with parts of the source electrode 70c and the drain electrode 70d. The semiconductor film 70b is, for example, an oxide semiconductor film, and may contain at least one metal element among In, Ga, and Zn. In the present embodiment, the semiconductor film 70b contains, for example, In—Ga—Zn—O-based semiconductor. Here, the In—Ga—Zn—O-based semiconductor is a ternary oxide of indium (In), gallium (Ga), and zinc (Zn), in which the ratio (composition ratio) of In, Ga, and Zn is not limited particularly, and examples of the ratio include In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, and In:Ga:Zn=1:1:2.
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Next, the following description describes a method for producing the active matrix substrate 1.
First, a black resist is applied over one of the surfaces of the glass substrate 100, and is patterned by photolithography. Through this step, a black matrix 60 is formed in the TFT area and the non-TFT area (see
Next, an inorganic insulating film 102 made of, for example, silicon nitride (SiNx) is formed so as to cover the black matrix 60 on the glass substrate 100 (see
Subsequently, for example, a film of titanium (Ti) and a film of copper (Cu) are formed sequentially on the inorganic insulating film 102, and photolithography and wet etching are carried out so as to pattern the laminate film of titanium (Ti) and copper (Cu). Through these steps, the source electrode 70c and the drain electrode 70d are formed on the inorganic insulating film 102 in the TFT area. Further, the data line 22 is formed on the inorganic insulating film 102 in the non-TFT area (see
Next, a semiconductor film containing, for example, In, Ga, Zn, and O is formed so as to cover the source electrode 70c and the drain electrode 70d in the TFT area, and photolithography and wet etching are carried out so as to pattern the semiconductor film. Through these steps, in the TFT area, the semiconductor film 70b is formed so as to overlap with parts of the source electrode 70c and the drain electrode 70d (see
Then, the gate insulating film 103 made of, for example, silicon oxide (SiOx) is formed so as to cover the source electrode 70c, the drain electrode 70d, and the semiconductor film 70b in the TFT area, and cover the data line 22 in the non-TFT area (see
Subsequently, a laminate metal film obtained by laminating, for example, titanium (Ti) and copper (Cu) sequentially is formed on the gate insulating film 103, and photolithography and wet etching are carried out so as to pattern the laminate metal film. Through these steps, in the TFT area, the gate electrode 70a is formed at a position that overlaps with the source electrode 70c, the drain electrode 70d, and the semiconductor film 70b (see
Next, an organic insulating film is formed so as to cover the gate electrode 70a and the gate insulating film 103 in the TFT area and the gate insulating film 103 in the non-TFT area. Then, the organic insulating film is patterned by photolithography. Through this step, the organic insulating film 104 is formed that has an opening 104a at a position that overlaps with the drain electrode 70d in the TFT area (see
Then, a transparent electrode film made of, for example, ITO is formed on the organic insulating film 104, and then, photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through this step, the counter electrode 23 is formed on the organic insulating film 104 in the TFT area and the non-TFT area (see
Next, the inorganic insulating film 105 made of, for example, silicon nitride (SiNx) is formed so as to cover the counter electrode 23 and the organic insulating film 104 in the TFT area and the counter electrode 23 in the non-TFT area (see
Then, a transparent electrode film made of, for example, ITO is formed on the inorganic insulating film 105, and then, photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through these steps, the pixel electrode 25 is formed on the inorganic insulating film 105 in the TFT area and the non-TFT area. The pixel electrode 25 is in contact with the drain electrode 70d in the TFT area, and includes slits 25a (see
Next, a metal film made of, for example, copper (Cu) is formed on the inorganic insulating film 105, and then, photolithography and wet etching are carried out so as to pattern the metal film. Through these steps, in the TFT area and the non-TFT area, the signal line 24 is formed at a position that does not overlap with the pixel electrode 25 (see
In the above-described embodiment, the counter electrodes 23 are on the glass substrate 100 side with respect to the pixel electrodes 25, and the liquid crystal layer 3 is not arranged between the touch surface and the counter electrodes 23. It is therefore unlikely that, during a touch detecting operation, the operation would be affected by changes in the liquid crystal capacitances, and a small change in the electrostatic capacitance when the touch surface is touched can be easily detected.
Further, shield electrodes are provided to reduce alignment defects caused in the liquid crystal layer 3 due to external electric fields in the horizontal electric field driving. In the above-described embodiment, shield electrodes 202 are provided on the backlight 5 side of the counter substrate 2, whereby alignment defects in the liquid crystal layer 3 caused by external electric fields from the counter substrate 2 side can be reduced. Further, in a case where the touch-panel-equipped display device 10 is of a thin type (for example, having a thickness of 0.3 to 0.6 mm), even if the touch-panel-equipped display device 10 is warped when a touch surface of the touch-panel-equipped display device 10 is touched, the shield electrodes 202 makes it unlikely that the electrostatic capacitances between the counter electrodes 23 and members provided on the back surface side of the touch-panel-equipped display device 10 (backlight and the like) would change, whereby decreases in the touch detection sensitivity can be reduced.
Further, in the above-described embodiment, the counter electrodes 23 are provided on the glass substrate 100 side with respect to the pixel electrodes 25, which allows the counter electrodes 23 to function as shield electrodes. This therefore makes it possible to improve the touch detection sensitivity, as compared with a case where the shield electrodes are provided on the side of the touch surface that a user's finger or the like touches in the glass substrate 100. In a case where the counter electrodes 23 are caused to function as shield electrodes in this way, it is preferable that the data lines 22 are arranged so that each overlaps with a space between adjacent ones of the counter electrodes 23 that are adjacent in the X-axis direction when viewed in a plan view in
Besides, each TFT 70 provided on the active matrix substrate 1 has such a top gate structure that the gate electrode 70a is arranged on the liquid crystal layer 3 side with respect to the semiconductor film 70b. This makes it unnecessary to additionally provide a light-shielding film for blocking light from the backlight 5 (see
In the active matrix substrate 1, the counter electrodes 23 and the pixel electrodes 25 are arranged so as to overlap with each other (see
The foregoing description of Embodiment 1 principally focuses on the TFT provided in the pixel, but the configuration of the gate driver 40 also include a plurality of TFTs. These TFT also may have a structure identical to that of the TFT 70 provided in the pixel.
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In the present embodiment, as compared with Embodiment 1, the inorganic insulating film 106 is needed additionally, and the signal line 24 is arranged in another layer different from the layer where the pixel electrode 25 is provided. More specifically, the signal line 24 is arranged in a layer closer to the glass substrate 100 than the pixel electrode 25 is. In addition to the effects achieved in Embodiment 1, this makes it possible to achieve the following effects: the electrostatic capacitances between the signal lines 24 and the pixel electrodes 25 are reduced as compared with Embodiment 1, and alignment disturbances in the liquid crystal layer 3 caused by electrostatic capacitances between the signal lines 24 and the pixel electrodes 25 can be reduced.
Incidentally, the production of the active matrix substrate 1A in the present embodiment is carried out as follows. After the steps shown in
Next, the inorganic insulating film 105 made of, for example, silicon nitride (SiNx) is formed on the organic insulating film 104 so as to cover the signal line 24 (see
Then, a transparent electrode film made of, for example, ITO is formed on the inorganic insulating film 105, and then, photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through these steps, the counter electrode 23 is formed on the inorganic insulating film 105 at a position that does not overlap with the signal line 24 (see
Subsequently, the inorganic insulating film 106 made of, for example, silicon nitride (SiNx) is formed on the inorganic insulating film 105 so as to cover the counter electrode 23 (see
Then, as is the case with Embodiment 1, the step shown in
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The inorganic insulating film 116 is made of, for example, silicon nitride (SiNx) or silicon dioxide (SiO2). The common electrode 231 is made of the same material as that of the counter electrode 23. The common electrode 231 is connected with the counter electrode 23, and when an image is displayed, the common electrode 231 has the same potential as that of the counter electrode 23, forming a capacitor between itself and the pixel electrode 251.
The present embodiment includes the counter electrodes 23 and the common electrodes 231 on the glass substrate 100 side and on the liquid crystal layer 3 side (see
Incidentally, the production of the active matrix substrate 1B in the present embodiment is carried out as follows. After the steps shown in
Next, a transparent electrode film made of, for example, ITO is formed on the organic insulating film 104, and photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through these steps, the counter electrode 23 is formed on the organic insulating film 104 at a position that does not overlap with the signal line 24 (see
Subsequently, the inorganic insulating film 105 made of, for example, silicon nitride (SiNx) is formed on the organic insulating film 104 so as to cover the signal line 24 and the counter electrode 23 (see
Then, a transparent electrode film made of, for example, ITO is formed on the inorganic insulating film 105, and then, photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through these steps, the pixel electrode 251 is formed at a position that overlaps with the counter electrode 23 (see
Next, the inorganic insulating film 116 made of, for example, silicon nitride (SiNx) is formed on the inorganic insulating film 105 so as to cover the pixel electrode 251 (see
Subsequently, a transparent electrode film made of, for example, ITO is formed on the inorganic insulating film 116, and then, photolithography and wet etching are carried out so as to pattern the transparent electrode film. Through these steps, the common electrode 231 is formed on the inorganic insulating film 116 at a position that does not overlap with the pixel electrode 251 (see
The foregoing description describes examples of the touch-panel-equipped display device according to the present invention, but the configuration of the touch-panel-equipped display device according to the present invention is not limited to the configurations of the above-described embodiments, but may have any one of a variety of modified configurations. The following description describes the modification examples.
In the above-described embodiments, the semiconductor film 70b is not limited to the oxide semiconductor film, but may be an amorphous silicon film.
The foregoing embodiments are described with reference to an example in which the touch-panel-equipped display device includes an active matrix substrate, a counter substrate, a liquid crystal layer, polarizing plates, and a backlight, but the touch-panel-equipped display device may include at least an active matrix substrate, a counter substrate, and a liquid crystal layer.
The foregoing embodiments are described with reference to an example in which the TFT has such a top gate structure that the gate electrode 70a is arranged on the liquid crystal layer 3 side with respect to the semiconductor film 70b; the TFT, however, may have such a bottom gate structure that the gate electrode 70a is provided on the glass substrate 100 side with respect to the semiconductor film 70b.
The foregoing embodiments are described with reference to an example in which the data lines 22 are arranged in such a manner that each of the same is arranged between adjacent ones of the counter electrodes 23 that are adjacent in the gate line 21 extending direction. The configuration, however, may be such that each gate line 21 is arranged between the counter electrodes 23 adjacent in the data line 22 extending direction. Or alternatively, the configuration may be such that at least one data line 22 is arranged between adjacent ones of the counter electrodes 23 that are adjacent in the gate line 21 extending direction, and additionally, at least one gate line 21 is arranged between adjacent ones of the counter electrodes 23 that are adjacent in the data line 22 extending direction.
Number | Date | Country | Kind |
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2016-162037 | Aug 2016 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2017/029732 | 8/21/2017 | WO | 00 |