Patent Application
20200201095
The present invention relates to a liquid crystal display device.
There has been a conventionally known a liquid crystal display device configured such that a TFT substrate is provided with a color filter and a counter substrate is provided with a black matrix (PTL 1 listed below). The color filter includes a plurality of colored portions placed in such a manner as to correspond to each separate pixel.
PTL 1: Japanese Unexamined Patent Application Publication No. 2014-41268
The foregoing configuration raises concern about a situation where of light traveling toward a liquid crystal layer through the TFT substrate, light having obliquely fallen on one of two adjacent colored portions travels toward a place in the liquid crystal layer that corresponds to the other colored portion. This raises concern about the occurrence of a mixture of colors of pixels, for example, due to the occurrence of a situation or the like where light having passed through a red colored portion is emitted from a pixel that corresponds to a green colored portion.
The present invention was made in view of the above circumstances. An object is to reduce a mixture of colors of pixels.
In order to solve the foregoing problems, a liquid crystal display device of the present invention includes: a pair of substrates placed opposite each other; a liquid crystal layer placed between the two substrates; a plurality of switching elements provided on a first one of the two substrates; a plurality of pixel electrodes provided on the first substrate, electrically connected to the plurality of switching elements, respectively, and placed closer to the liquid crystal layer than the plurality of switching elements; a common electrode, provided on the first substrate, at least a part of which overlaps the pixel electrodes via an insulating film; a color filter, provided on the first substrate, placed between the switching elements and the pixel electrodes, and placed in such a manner as to overlap each of the plurality of pixel electrodes, that includes a plurality of colored portions that exhibit different colors from one another; and a light-blocking conducting film provided on the first substrate, placed closer to the liquid crystal layer than the switching elements while having a light blocking effect, placed in such a manner as to overlap a boundary portion between two adjacent colored portions of the plurality of colored portions, and electrically connected to the common electrode.
In a case where light has fallen on a side of the color filter opposite to the liquid crystal layer, of light having obliquely fallen on one of the two adjacent colored portions, light traveling toward a place in the liquid crystal layer that corresponds to the other color portion can be blocked by the light-blocking conducting film, so that a mixture of colors of pixels can be reduced. Further, the light-blocking conducting film, which is electrically connected to the common electrode, can for example achieve a reduction in resistance of the common electrode and be used as a wire through which to transmit a signal to the common electrode.
Further, the light-blocking conducting film may be placed closer to the liquid crystal layer than the color filter. If the light-blocking conducting film is placed opposite the liquid crystal layer behind the color filter, a portion of light traveling toward the liquid crystal layer that has passed through an area near the light-blocking conducting film travels toward the colored portions. As a result, this raises concern about a situation where the light having passed through the area near the light-blocking conducting film passes through one of the colored portions first and then travels toward a place in the liquid crystal layer that corresponds to the other colored portion. On the other hand, according to the foregoing configuration, light having passed through the colored portions can be blocked by the light-blocking conducting film, so that a mixture of colors of pixels can be more surely reduced.
Further, the light-blocking conducting film may make surface contact with the common electrode. Bringing the light-blocking conducting film into surface contact with the common electrode can make a conducting portion thicker by the thickness of the light-blocking conducting film, thus making it possible to achieve a reduction in resistance.
Further, the common electrode may serve as a position detection electrode that forms an electrostatic capacitance with a position input body which performs a position input and that detects a position input performed by the position input body, and the light-blocking conducting film may be a wire that is capable of transmitting a signal to the position detection electrode. The light-blocking conducting film can be used as a wire for the position detection electrode.
Further, each of the switching elements may include a source electrode, the first substrate may be provided with a source line that is electrically connected to the source electrode, and the light-blocking conducting film may be placed in such a manner as to overlap the source line. This configuration can achieve higher efficiency in the use of light than a configuration in which the light-blocking conducting film and the source line are placed in such a manner as not to overlap each other.
Each of the switching elements may be a TFT including an oxide semiconductor. Since the oxide semiconductor is high in electron mobility, the switching element can be made smaller in size. This brings about an advantage in terms of an increase in definition and an increase in aperture ratio. Further, a reduction in leak current brings about an advantage in terms of a reduction in power consumption. Further, the oxide semiconductor may contain indium (In), gallium (Ga), zinc (Zn), and oxygen (O).
The present invention makes it possible to reduce a mixture of colors of pixels.
Embodiment 1 of the present invention is described with reference to
Further, the liquid crystal display device 10 includes a pair of front and back exterior members 15 and 16 assembled to each other to accommodate and retain the liquid crystal panel 11 and the backlight device 14. Of them, the front exterior member 15 has an opening 15A formed therein so that an image displayed in a display area AA of the liquid crystal panel 11 can be viewed from outside. The liquid crystal display device 10 according to the present embodiment is one that is used in various types of electronic apparatus (not illustrated) such as mobile phones (including smartphones and the like), laptop personal computers (including tablet laptop personal computers and the like), wearable terminals (including smartwatches and the like), portable information terminals (including electronic books, PDAs, and the like), portable game machines, and digital photo frames. For this purpose, the liquid crystal panel 11 of the liquid crystal display device 10 has a screen size of approximately several inches to several tens of inches, which is a size generally categorized as a small size or a small-to-medium size.
The liquid crystal panel 11 has the display area AA, which is capable of displaying an image, and a non-display area NAA placed on the periphery in such a manner as to surround the display area AA. The liquid crystal panel 11 has a vertically long square shape (rectangular shape) as a whole, with the driver 17 attached to one end of the liquid crystal panel 11 in a long-side direction (i.e. a right-left direction of
As shown in
As shown in
The gate conducting film 31 has electrical conductivity and a light blocking effect by being a single layer made of one type of metal material or a laminated film or alloy made of different types of metal material, and constitutes a gate electrode 31G of a TFT 43 provided on the array substrate 22 and a gate line (not illustrated). An appropriately usable example of the gate conducting film 31 is a film containing a metal such as copper (Cu), titanium (Ti), molybdenum (Mo), aluminum (Al), magnesium (Mg), cobalt (Co), chromium (Cr), or tungsten (W), an alloy thereof, or a metal nitride thereof. The gate insulating film 32 mainly keeps the gate conducting film 31 and the semiconductor film 33 insulated from each other. The semiconductor film 33 is constituted by a thin film made, for example, of an oxide semiconductor as a material, and constitutes a channel part (semiconductor part) in the TFT 43 that is connected to the source electrode 34S and the drain electrode 34D. A possible example of the oxide semiconductor of which the semiconductor film 33 is made is an oxide semiconductor (semiconductor based on In—Ga—Zn—O) containing In (indium), Ga (gallium), Zn (zinc), and O (oxygen). Since the oxide semiconductor is high in electron mobility, the TFT 43 can be made smaller in size. This brings about an advantage in terms of an increase in definition and an increase in aperture ratio. Further, a reduction in leak current brings about an advantage in terms of a reduction in power consumption. Alternatively, an amorphous silicon TFT or a polysilicon TFT may be applied as the TFT 43.
The source conducting film 34 has electrical conductivity and a light blocking effect by being a single layer made of one type of metal material or a laminated film or alloy made of different types of metal material, and constitutes a source line 34A (see
The color filter 50 is placed between the planarizing film 36 and the common electrode 40 and, by extension, between the TFT 43 and the pixel electrode 42. As shown in
An appropriately usable example of the light-blocking conducting film 38 is a film containing a metal such as copper (Cu), titanium (Ti), molybdenum (Mo), aluminum (Al), magnesium (Mg), cobalt (Co), chromium (Cr), or tungsten (W), an alloy thereof, or a metal nitride thereof. The light-blocking conducting film 38 has a light blocking effect and is placed closer to the liquid crystal layer 23 than the TFT 43. Further, the light-blocking conducting film 38 is placed closer to the liquid crystal layer 23 than the color filter 50 and, as shown in
The insulating film 41 is placed in such a manner as to cover the common electrode 40 and the light-blocking conducting film 38. The pixel electrode 42 is placed on top of the insulating film 41. The gate insulating film 32, the insulating film 35, and the insulating film 41 are inorganic insulating films made of an inorganic material such as silicon nitride (SiNx) or silicon oxide (SiO2), and have moisture-proof properties. A plurality of the pixel electrodes 42 are arranged in a matrix in the display area. Further, in the display area, a plurality of the TFTs 43, which serve as switching elements, are arranged in a matrix in correspondence with the pixel electrodes 42. The TFT 43 includes the gate electrode 31G, the semiconductor film 33, the source electrode 34S, and the drain electrode 34D. The pixel electrode 42 is placed closer to the liquid crystal layer 23 than the TFT 43 and is electrically connected to the drain electrode 34D via a contact hole CH1 formed in the insulating film 35.
The TFT 43 is provided at a place where a gate line (not illustrated) and the source line 34A cross each other, and is driven in accordance with various types of signal that are supplied to the gate line and the source line 34A, and the driving of the TFT 43 entails control of supply of a potential to the pixel electrode 42. The pixel electrode 42 has a plurality of slits 42A as indicated by chain double-dashed lines in
Next, effects of the present embodiment are described. In the present embodiment, light emitted from the backlight device 14 falls on a side of the color filter 50 opposite to the liquid crystal layer 23. In such a case, of light having obliquely fallen on one (in
Further, the light-blocking conducting film 38 is placed closer to the liquid crystal layer 23 than the color filter 50. If the light-blocking conducting film 38 is placed opposite the liquid crystal layer 23 behind the color filter 50 (see a light-blocking conducting film 38A indicated by a chain double-dashed lines in
Further, the light-blocking conducting film 38 is configured to make surface contact with the common electrode 40. Bringing the light-blocking conducting film 38 into surface contact with the common electrode 40 can make a conducting portion (the common electrode 40 and the light-blocking conducting film 38) thicker by the thickness of the light-blocking conducting film 38, thus making it possible to achieve a reduction in resistance. Further, the TFT 43, which serves as a switching element, includes the source electrode 34S. The array substrate 22 is provided with the source line 34A, which is electrically connected to the source electrode 34S. The light-blocking conducting film 38 is placed in such a manner as to overlap the source line 34A. This configuration can achieve higher efficiency in the use of light than a configuration in which the light-blocking conducting film 38 and the source line 34A are placed in such a manner as not to overlap each other (e.g. in such a manner as to be displaced from each other in the X-axis direction).
Next, Embodiment 2 of the present invention is described with reference to
Next, a more specific configuration of the array substrate 122 of the present embodiment is described with reference to the drawings.
The crystalline silicon TFT 110A has an active region composed mainly of crystalline silicon. The oxide semiconductor TFT 110B has an active region composed mainly of an oxide semiconductor. The term “active region” here refers to a region, included in a semiconductor layer serving as an active layer of a TFT, in which a channel is formed. The crystalline silicon TFT 110A has a crystalline silicon semiconductor film 113 (e.g. a low-temperature polysilicon film), an insulating film 114 covering the crystalline silicon semiconductor film 113, and a gate electrode 115A provided on top of the insulating film 114. A portion of the insulating film 114 located between the crystalline silicon semiconductor film 113 and the gate electrode 115A functions as a gate insulating film of the crystalline silicon TFT 110A. The crystalline silicon semiconductor film 113 has a region (active region) 113C in which a channel is formed and source and drain regions 113S and 113D located on both sides, respectively, of the active region. In this example, a portion of the crystalline silicon semiconductor film 113 that overlaps the gate electrode 115A via the insulating film 114 serves as the active region 113C. The crystalline silicon TFT 110A also has source and drain electrodes 118SA and 118DA connected to the source and drain regions 113S and 113D, respectively. The source electrode 118SA and the drain electrode 118DA are provided on top of an insulating film 116 covering the gate electrode 115A, and are connected to the crystalline silicon semiconductor film 113 via a contact hole formed in the insulating films 114 and 116.
The oxide semiconductor TFT 110B has a gate electrode 115B, an insulating film 116 covering a gate electrode 115B, and an oxide semiconductor film 117 disposed on top of the insulating film 116. The oxide semiconductor film 117 is formed on top of the insulating film 116. A portion of the insulating film 116 located between the gate electrode 115B and the oxide semiconductor film 117 functions as a gate insulating film of the oxide semiconductor TFT 110B. The oxide semiconductor film 117 has a region (active region 117C) in which a channel is formed and source contact and drain contact regions 117S and 117D located on both sides, respectively, of the active region. A portion of the oxide semiconductor film 117 that overlaps the gate electrode 115B via the insulating film 116 serves as the active region 117C. Further, the oxide semiconductor TFT 110B has source and drain electrodes 118SB and 118DB connected to the source contact and drain contact regions 117S and 117D, respectively.
The TFTs 110A and 110B are covered with an insulating film 119 and a planarizing film 120. In the oxide semiconductor TFT 110B, the gate electrode 115B, the source electrode 118SB, and the drain electrode 118DB are connected to a gate line (not illustrated), a source line 134A (see
The crystalline silicon TFT 110A has a top-gate structure in which the crystalline silicon semiconductor film 113 is disposed between the gate electrode 115A and the array substrate 122. Meanwhile, the oxide semiconductor TFT 110B (switching element) has a bottom-gate structure in which the gate electrode 115B is disposed between the oxide semiconductor film 117 and the array substrate 122. Employing such structures makes it possible to reduce the number of manufacturing steps and the cost of manufacturing in integrally forming two types of TFT 110A and 110B on top of the array substrate 122. The crystalline silicon TFT 110A and the oxide semiconductor TFT 110B are not limited to the aforementioned TFT structures. For example, these TFTs 110A and 110B may have the same TFT structure. Alternatively, the crystalline silicon TFT 110A may have a bottom-gate structure, and the oxide semiconductor TFT 110B may have a top-gate structure. Further, in the case of a bottom-gate structure, it may be of a channel-etch type or an etch-stop type as in the case of the crystalline silicon TFT 110A. Further, it may be of a bottom-contact type in which a source electrode and a drain electrode are located below a semiconductor layer.
The insulating film 116, which serves as the gate insulating film of the oxide semiconductor TFT 110B, is extended to a region in which the crystalline silicon TFT 110A is formed, and functions as an interlayer insulating film that covers the gate electrode 115A and crystalline silicon semiconductor film 113 of the crystalline silicon TFT 110A. The gate electrode 115A of the crystalline silicon TFT 110A and the gate electrode 115B of the oxide semiconductor TFT 110B may be formed from the same type of conducting film. Further, the source and drain electrodes 118SA and 118DA of the crystalline silicon TFT 110A and the source and drain electrodes 118SB and 118DB of the oxide semiconductor TFT 110B may be formed from the same type of conducting film. The formation from the same type of conducting film makes it possible to further reduce the number of steps.
In the present embodiment, the oxide semiconductor layer 117 contains, for example, a semiconductor based on In-Ga—Zn—O hereinafter referred to as “In-Ga—Zn—O semiconductor”). In this example, the In-Ga—Zn—O semiconductor is a ternary oxide of In (indium), Ga (gallium), and Zn (zinc) and, without a particular limitation on the proportions (composition ratios) of In, Ga, and Zn, contains, for example, In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, In:Ga:Zn=1:1:2, or the like. The semiconductor based on In-Ga—Zn—O may be amorphous or crystalline. A preferred example of a crystalline semiconductor based on In-Ga—Zn—O is a crystalline semiconductor based on In-Ga—Zn—O whose c axis is oriented substantially perpendicular to a layer plane. A crystal structure of such an In-Ga—Zn—O semiconductor is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2012-134475. The entire contents of Japanese Unexamined Patent Application Publication No. 2012-134475 are hereby incorporated by reference.
The oxide semiconductor layer 117 may contain another oxide semiconductor instead of the In-Ga—Zn—O semiconductor. For example, the oxide semiconductor layer 117 may contain a Zn—O semiconductor, an In—Zn—O semiconductor, a Zn—Ti—O semiconductor, a Cd—Ge—O semiconductor, a Cd—Pb—O semiconductor, a CdO (cadmium oxide), a Mg—Zn—O semiconductor, an In—Sn—Zn—O semiconductor (e.g. In2O3—SnO2—ZnO), an In—Ga—Sn—O semiconductor, or the like. In the present embodiment, the color filter 50 is placed on top of the planarizing film 120. A light-blocking conducting film 138 is placed closer to the liquid crystal layer (on the upper side of
Next, Embodiment 3 of the present invention is described with reference to
When a user of the liquid crystal display device moves his/her finger (position input body; not illustrated), which is a conductor, nearer to a surface (display surface) of the liquid crystal panel 211, electrostatic capacitances are formed between the finger and the touch electrodes 240A. As a result, an electrostatic capacitance that is detected by a touch electrode 240A located near the finger is different from that which is detected by a touch electrode 240A located away from the finger. This makes it possible to detect an input position on the basis of the difference. Moreover, the position detection electrodes 240A are constituted by the common electrode 240 provided on the array substrate 222. A light-blocking conducting film 238 is placed in such a manner as to overlap a boundary portion 51 between two adjacent colored portions (in
In a place in the insulating films 241 and 243 that overlaps the light-blocking conducting film 238, a contact hole CH4 is formed in such a manner as to pass through the insulating films 241 and 243. The common electrode 240 is connected to the light-blocking conducting film 238 via the contact hole CH2. As shown in
This makes it possible to use the light-blocking conducting film 238 as wires that are capable of transmitting signals to the position detection electrodes 240A. The source line 34A is connected to the driver 17, and the gate line 31A is connected, for example, to a gate driver 218 provided on the array substrate 222. The light-blocking conducting film 238 supplies the position detection electrodes 240A at different timings with a reference potential signal pertaining to the display function and a touch signal (position detection signal) pertaining to the touch function. This reference potential signal is transmitted to all of the light-blocking conducting films 238 at the same timing, and all of the position detection electrodes 240 are brought to a reference potential to function as the common electrode 240.
Next, Embodiment 4 of the present invention is described with reference to
In a place in the insulating film 243 that overlaps the light-blocking conducting film 238, a contact hole CH6 is formed in such a manner as to pass through the insulating film 243. The common electrode 240 is connected to the light-blocking conducting film 238 via the contact hole CH6. Further, the present embodiment differs from Embodiment 3 (see
Next, Embodiment 5 of the present invention is described with reference to
Embodiment 4 described above is configured such that as shown in
Alternatively, as shown in a modification of
The present invention is not limited to the embodiments described above with reference to the drawings. The following embodiments may be included in the technical scope of the present invention.
(1) The materials of each conducting film and each insulating film are not limited to the materials illustrated in the foregoing embodiments but may be changed as appropriate.
(2) Each of the foregoing embodiments may be configured such that the light-blocking conducting film is placed on a side of the color filter opposite to the liquid crystal layer and the light-blocking conducting film and the common electrode are connected to each other via a contact hole bored through the color filter. When Embodiments 3 and 4 are configured such that the light-blocking conducting film 238 is placed on a side of the color filter 50 opposite to the liquid crystal layer, the distance in the Z-axis direction between the light-blocking conducting film 238, which serves as a wire, and the common electrode 240, which is not connected to the light-blocking conducting film 238, is greater by the thickness of the color filter 50. This causes a smaller parasitic capacitance to be formed between the light-blocking conducting film 238 and the common electrode 240, bringing about improvement in position detection sensitivity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-114107 | Jun 2017 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2018/021180 | 6/1/2018 | WO | 00 |
