The present invention relates to a liquid crystal display device equipped with in-cell touch panel functionality.
Conventionally, display devices equipped with touch panels have been put to widespread use. In recent years, display devices equipped with in-cell touch panels (touch panels embedded in display panels) have been introduced (hereinafter, such a display device will also be referred to simply as “display device”) for the purpose of reducing thickness and weight, improving viewability, reducing the number of components for costs reduction, and the like (see, for example, Patent Literature 1).
As illustrated in
A CF layer 318, which includes light shielding parts 316 (BM) and a plurality of colored layers 317 (CF) provided between adjacent light shielding parts 316, is provided between an insulating substrate 311 and a counter electrode 319 (common electrode) which are included in the CF substrate 302. Between the CF layer 318 and the insulating substrate 311, first electrode layers 312 and second electrode layers 314 are provided to as sensor electrodes (location determining electrodes). Between the first electrode layers 312 and the second electrode layers 314, an insulating layer 313 is provided.
As illustrated in
According to the display device 300, a touch location of a finger or a pen for an input operation (detection target) is determined by detecting a change in capacitance when the detection target touches a display screen (capacitive method). This allows a touch location to be determined with a simple configuration.
Patent Literature 1
According to the display device 300, (i) the second electrode layers 314 and the counter electrode 319 are in close proximity to each other and (ii) the counter electrode 319 is provided as one solid electrode all over the display panel. This causes a large amount of parasitic capacitance to be formed between the second electrode layers 314 and the counter electrode 319, and therefore causes a driving load of the sensor electrodes to be large. Hence, it is not possible to obtain a sufficient S/N ratio (signal-to-noise ratio), and therefore a problem of reduction in detection performance occurs.
The present invention has been made in view of the problem, and it is an object of the present invention to configure a liquid crystal display device equipped with in-cell touch panel functionality to increase location determining performance by reducing a driving load on sensor electrodes (location determining electrodes).
In order to attain the object, a liquid crystal display device of the present invention is a liquid crystal display device equipped with touch panel functionality in which specified coordinates of a detection target are determined by a change in capacitance, said liquid crystal display device including: an active matrix substrate; a counter substrate; an liquid crystal layer sandwiched between the active matrix substrate and the counter substrate; pixel electrodes and a counter electrode configured to cause a voltage to be applied across the liquid crystal layer; drive electrodes and detection electrodes configured to determine the specified coordinates; drive electrode-specific auxiliary wires electrically connected to the drive electrodes; and detection electrode-specific auxiliary wires electrically connected to the detection electrodes, a plurality of domains being formed in each of pixels, and the drive electrode-specific auxiliary wires and/or the detection electrode-specific auxiliary wires being provided so as to overlap boundaries of the plurality of domains when the liquid crystal display device is viewed two-dimensionally.
With the configuration, it is possible to reduce, by providing the drive electrode-specific auxiliary wires and the detection electrode-specific auxiliary wires, wire resistance of the detection electrodes and the drive electrodes which serve as sensor electrodes (location determining electrodes). This allows for a reduction in driving load of the sensor electrodes, and therefore restricts a reduction in S/N ratio. Therefore, it is possible to increase location determining performance of a touch panel in comparison with the conventional configuration (see
The liquid crystal display device is preferably configured such that the drive electrode-specific auxiliary wires and the detection electrode-specific auxiliary wires are narrower in line width than dark lines that occur on the boundaries of the plurality of domains.
The liquid crystal display device can be configured such that: the drive electrode-specific auxiliary wires and the detection electrode-specific auxiliary wires are provided so as to be orthogonal to each other when the liquid crystal display device is viewed two-dimensionally; and either one of the drive electrode-specific auxiliary wires and the detection electrode-specific auxiliary wires is provided at regular intervals for every N (N is an integer that is not less than 1 and not more than the number of colors of which a color filter is made up) pixels whereas the other one of the drive electrode-specific auxiliary wires and the detection electrode-specific auxiliary wires is provided at regular intervals for every pixel.
The liquid crystal display device is preferably configured such that the pixel electrodes and/or the counter electrode are/is provided with slits configured to control alignment of liquid crystal molecules of the liquid crystal layer.
Hence, it is possible to easily realize a multi-domain configuration.
The liquid crystal display device can be configured such that the slits are arranged in a radial pattern extending from a center part of each of the pixels toward end parts of said each of the pixels.
The liquid crystal display device can be configured such that the slits are arranged in at least two differing directions.
The liquid crystal display device can be configured such that the pixel electrodes and the counter electrode (i) are each formed in a comb-like form and (ii) each include a plurality of comb-like electrodes; and the plurality of comb-like electrodes of the pixel electrodes and the plurality of comb-like electrodes of the counter electrode mesh with each other.
The liquid crystal display device of the present invention is thus configured such that the counter electrode is provided with slits for controlling alignment of liquid crystal molecules of the liquid crystal layer. This allows a liquid crystal display device equipped with in-cell touch panel functionality to increase location determining performance by reducing a driving load on sensor electrodes (location determining electrodes).
The following description will discuss an embodiment of a liquid crystal display device of the present invention, which is equipped with in-cell touch panel functionality (hereinafter referred to simply as “liquid crystal display device”).
The liquid crystal panel 2 is an active matrix display panel in which a liquid crystal layer 6 is sandwiched between a pair of substrates (an active matrix substrate 4 (TFT substrate) and a counter substrate 5 (color filter (CF) substrate)). According to the liquid crystal panel 2, (i) the counter substrate 5 faces an observer (detection target) and (ii) the backlight 3 is provided to face a back surface of the active matrix substrate 4.
The active matrix substrate 4 includes a glass substrate 41, and includes, on the glass substrate 41, (i) various signal lines such as scan signal lines and data signal lines (not illustrated), (ii) transistors (TFTs) (not illustrated), (iii) an insulating film 42, (iv) pixel electrodes 43 corresponding to respective pixels provided in a matrix, and (v) a polarizing plate 44. The active matrix substrate 4 can have a well-known configuration.
The counter substrate 5 has a configuration for realizing image display functionality and a configuration for realizing touch panel functionality. An example of a specific configuration of the liquid crystal display device will be discussed below.
A liquid crystal display device in accordance with Example 1 is configured as illustrated in
The counter substrate 5 includes (i) a glass substrate 11, (ii) a plurality of detection electrodes 12 and a plurality of drive electrodes 13 serving as location determining electrodes (sensor electrodes), (iii) detection electrode-specific auxiliary wires 12a, (iv) drive electrode-specific auxiliary wires 13a, (v) a first insulating film 14, (vi) a second insulating film 15, (vii) a black matrix (not illustrated), (viii) a color filter layer (not illustrated), (ix) a counter electrode 16, and (x) a polarizing plate 17.
When the liquid crystal panel 2 is viewed two-dimensionally as illustrated in
The detection electrodes 12 and the drive electrodes 13 are transparent, and are each made of, for example, a transparent conductive material such as an oxide. Examples of the transparent conductive material encompass ITO (indium tin oxide), IZO (indium zinc oxide), zinc oxide, and tin oxide. Alternatively, the detection electrodes 12 and the drive electrodes 13 can each be transparent as a result of being a thin electrode. Examples of the thin electrode encompass (i) a metal thin-film electrode such as graphene and (ii) a thin-film carbon electrode.
The detection electrodes 12 and the drive electrodes 13 allow the capacitive-method touch panel functionality to be realized. An operating principle of a capacitive method-based touch panel will be described below with reference to
In
In (a) of
In so doing, when a fingertip 94 touches a front surface of the cover glass 93 as illustrated in (c) of
A capacitive-based location determining method is not limited to the above method, but can be a well-known method. That is, it is possible to employ a mutual capacitive method-based touch panel or a self-capacitive method-based touch panel.
Note that the liquid crystal panel 2 is of a multi-domain RTN mode in which optical alignment process or the like provides tilt angles to liquid crystal molecules 6a in the vicinity of the pixel electrodes 43 and the counter electrode 16 so that a plurality of domains are formed. In the example shown in
The detection electrodes-specified auxiliary wires 12a are electrically connected to detection electrodes 12 while the drive electrodes-specified auxiliary wires 13a are electrically connected to drive electrodes 12.
When the liquid crystal panel 2 is viewed two-dimensionally, the detection electrodes-specified auxiliary wires 12a and the drive electrodes-specified auxiliary wires 13a are provided so as to overlap dark lines 6c that occur at domain boundaries 6b (see
Although
As illustrated
Since the auxiliary wires 12a and 13a are thus provided, it is possible to reduce wire resistance of the detection electrodes 12 and the drive electrodes 13. This allows for a reduction in a driving load on sensor electrodes (the detection electrodes 12 and the drive electrodes 13), and therefore restricts a reduction in S/N ratio. Therefore, it is possible to increase location determining performance of a touch panel in comparison with the conventional configuration (see
According to the liquid crystal panel 2 of Example 2, pixel electrodes 43 are each provided with a plurality of slits 43s for controlling alignment of liquid crystal molecules 6a of a liquid crystal layer 6 (see
According to the configuration of Example 2, an alignment direction is controlled by the slits 43s which are provided in four differing directions. This, when a voltage is applied, causes the liquid crystal molecules 6a to be aligned in a radial pattern, so that four domains are formed in each of the pixels. Therefore, the liquid crystal display device 1 of Example 2 produces an advantageous effect identical to that produced by the liquid crystal display device 1 of Example 1.
According to the liquid crystal panel 2 of Example 3, as illustrated in
The detection electrode-specific auxiliary wires 12a are formed so as to overlap dark lines 6c that occur on respective domain boundaries 6b formed linearly in the row direction. The drive electrode-specific auxiliary wires 13a are formed so as to overlap dark lines 6c that occur on domain boundaries 6b formed in a V-shape. Therefore, the liquid crystal display device 1 of Example 3 produces an advantageous effect similar to that produced by the liquid crystal display device 1 of Example 1.
Note that although
According to the liquid crystal panel 2 of Example 4, as illustrated in
Detection electrode-specific auxiliary wires 12a are provided so as to overlap dark lines 6c that occur on domain boundaries 6b formed linearly in the row direction. Therefore, the liquid crystal display device 1 of Example 4 produces an advantageous effect similar to that produced by the liquid crystal display device 1 of Example 1.
Note that the liquid crystal panel 2 of Example 4 employing the IPS mode does not require the counter electrode 16 on a counter substrate 5. Therefore, according to
Note also that since the number of domains is normally two in an IPS mode, there occurs only one dark line 6c on one domain boundary 6b. Therefore,
According to the liquid crystal panel 2 of Example 5, slits 43s are provided in a V-shape on pixel electrodes 43 as illustrated in
As is the case of an IPS mode, an FFS mode also realizes a multi-domain configuration by designing the slits 43s of the pixel electrodes 43 to be angled by several degrees. In so doing, auxiliary wires 12a and 13a are provided so as to overlap dark lines 6c that occur on domain boundaries 6b which differ in angle from each other. Therefore, the liquid crystal display device 1 of Example 5 produces an advantageous effect similar to that produced by the liquid crystal display device 1 of Example 1.
Note that according to the liquid crystal panel 2 of Example 5 employing an FFS mode, a counter electrode 16 is provided on an active matrix substrate 4. Therefore, as is the case of an IPS mode, there is no need to provide the counter electrode 16 on a counter substrate 5. Therefore, according to
Note also that since the number of domains is normally two in an FFS mode as with an IPS mode, there occurs only one dark line 6c on one domain boundary 6b. Therefore,
The present invention is not limited to the description of the embodiments, but can be altered in many ways by a person skilled in the art within the scope of the claims. An embodiment derived from a proper combination of technical means disclosed in different embodiments is also encompassed in the technical scope of the present invention.
A liquid crystal display device of the present invention equipped with touch panel functionality is suitable for various mobile devices, large displays, and the like.
1 Liquid crystal display device
2 Liquid crystal panel
3 Backlight
4 Active matrix substrate
5 Counter substrate
6 Liquid crystal layer
6
a Liquid crystal molecule
6
b Domain boundary
6
c Dark line
11 Glass substrate
12 Detection electrode (location determining electrode)
12
a Detection electrode-specific auxiliary wire
13 Drive electrode (location determining electrode)
13
a Drive electrode-specific auxiliary wire
14 First insulating film
15 Second insulating film
16 Counter electrode
16
a Comb-like electrode
16
s Slit
17 Polarizing plate
41 Glass substrate
42 Insulating film
43 Pixel electrode
43
a Comb-like electrode
43
s Slit
44 Polarizing plate
Number | Date | Country | Kind |
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2012-177579 | Aug 2012 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/071330 | 8/7/2013 | WO | 00 |