Pixel structure with multilayered common electrodes and touch panel thereof

A pixel structure includes a scan line, a data line, a switching element, a planarization layer, a first common electrode, a common line, a first insulating layer, a pixel electrode, a second insulating layer, and a second common electrode. The switching element includes a source and a drain. The common line is located on the planarization layer and directly connected with the first common electrode. The planarization layer is located on the scan line, the data line, and the switching element. The pixel electrode is electrically connected with the drain through a first contact hole, wherein the first contact hole penetrates through the planarization layer and the first insulating layer. The second common electrode is electrically connected with the first common electrode through a second contact hole, wherein the second contact hole penetrates through the first insulating layer and the second insulating layer. A touch panel is also provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan application Ser. No. 107111128, filed on Mar. 30, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

1. Field of the Invention

This disclosure is related to a pixel structure and a touch panel, especially related to a pixel structure including a first common electrode and a second common electrode as well as a touch panel comprising the pixel structures.

2. Description of Related Art

With the advancement of technology, the power consumption of liquid crystal display (LCD) panels has been widely discussed. The research results show that when the operation frequency of the LCD panel is down-converted, the lower frequency of the signal output can achieve energy-saving effects.

However, when the liquid crystal display panel is operated at a low frequency (for example, less than 60 Hz), it is easy to cause a drop in the frame's brightness, which can be recognized by human eyes, because of the leakage of the pixel structures. When charging is performed on the next frame, the brightness will be increased significantly to generate the flicker problem. Therefore, there is an urgent need to have a solution that can solve the problems above.

SUMMARY

According to one embodiment of this invention, a pixel structure is provided to improve the flicker problem of an LCD panel operated at a low frequency.

According to another embodiment of this invention, a touch panel is provided to improve the flicker problem of an LCD panel operated at a low frequency.

In at least one embodiment of this invention, a pixel structure is provided. The pixel structure comprises a scan line, a data line, a switching element, a planarization layer, a first common electrode, a common line, a first insulating layer, a pixel electrode, a second insulating layer, and a second common electrode. The switching element is electrically connected to the scan line and the data line. The switching element includes a source and a drain. The planarization layer is located on the scan line, the data line, and the switching element. The first common electrode is located on the planarization layer. The common line is located on the planarization layer and directly connected with the first common electrode. The pixel electrode is located on the first insulating layer. The pixel electrode is electrically connected with the drain through a first contact hole. The first contact hole penetrates through the planarization layer and the first insulating layer. The second insulation layer is located on the pixel electrode. The second common electrode is located on the second insulation layer. The second common electrode is electrically connected with the first common electrode through a second contact hole. The second contact hole penetrates through the first insulating layer and the second insulating layer.

In at least one embodiment of this invention, a touch panel is provided. The touch panel comprises a first pixel structure and a second pixel structure. Each of the first and the second pixel structures comprises a scan line, a data line, a switching element, a planarization layer, a first common electrode, a common line, a first insulating layer, a pixel electrode, a second insulating layer, and a second common electrode. The switching element is electrically connected to the scan line and the data line. The switching element includes a source and a drain. The planarization layer is located on the scan line, the data line, and the switching element. The first common electrode is located on the planarization layer. The common line is located on the planarization layer and directly connected with the first common electrode. The pixel electrode is located on the first insulating layer. The pixel electrode is electrically connected with the drain through a first contact hole. The first contact hole penetrates through the planarization layer and the first insulating layer. The second insulation layer is located on the pixel electrode. The second common electrode is located on the second insulation layer. The second common electrode is electrically connected with the first common electrode through a second contact hole. The second contact hole penetrates through the first insulating layer and the second insulating layer. The common line of the first pixel electrode and the common line of the second pixel electrode are separated from each other.

One aspect of this invention is to improve the flicker problem of an LCD panel operated at a low frequency.

Another aspect of this invention is to increase the aperture ratio of a pixel structure.

To make the above features and advantages of the present invention more obvious and easy to understand, the following embodiments will be described in detail with the accompanying drawings as follows.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1Ais a schematic top view of a pixel structure and its surrounding components in accordance with an embodiment of the present invention.FIG. 1Bis a schematic cross-sectional view of a pixel structure according to the section line AA′ofFIG. 1A.FIG. 1Cis a schematic cross-sectional view of a pixel structure according to the section line BB′ ofFIG. 1A.

Please refer toFIGS. 1A to 1C. The pixel structure10comprises a scan line SL, a data line DL, a switching element T, a planarization layer140, a first common electrode CE1, a common line CL, a first insulating layer150, a pixel electrode PE, a second insulating layer160, and a second common electrode CE2. In this embodiment, the pixel structure10further comprises a substrate100, a light shielding layer SM, a buffer layer110, a gate insulating layer120, and an interlayer dielectric layer130, but the invention is not limited thereto. InFIG. 1A, three first common electrodes CE1′ and three pixel electrodes PE′ are also depicted. The first common electrode CE1′ and the pixel electrode PE′ are components of other pixel structures adjacent to the pixel structure10. The buffer layer110is located on the substrate100. The material of the buffer layer110is an insulating material, for example.

The switching element T has a source S, a drain D, a gate G, and a channel CH. The channel CH is located on the buffer layer110. The gate G overlaps the channel CH, and a gate insulating layer120is sandwiched between the gate G and the channel CH. The gate G is electrically connected to the scan line SL. The material of the gate G is a conductive material. For example, the material of the gate G may be copper (Cu), molybdenum (Mo), titanium (Ti), aluminum (Al), a tungsten, tungsten (W), silver (Ag), gold (Au), alloys of the above metals, or any combinations thereof. The gate G may be a single-layer structure or a multi-layer structure. In this embodiment, the switching element T is a double-gate switching element. That is, the switching element T comprises two gates G, whereby the leakage current can be reduced. However, the present invention is not limited thereto. According to other embodiments, the switching element T may also be a single-gate switching element.

The interlayer dielectric layer130covers the gate insulating layer120and the gate G at the same time. That is, the gate G is located between the interlayer dielectric layer130and the gate insulating layer120.

The drain D and the source S are on the interlayer dielectric layer130. The through hole Vd is located in the interlayer dielectric layer130and the gate insulating layer120, and the through hole Vs is located in the interlayer dielectric layer130and the gate insulating layer120. The drain D is electrically connected to the channel CH through the through hole Vd, and the source S is electrically connected to the channel CH through the through hole Vs. The source S is electrically connected to the data line DL. The drain electrode D is electrically connected to the pixel electrode PE. In some embodiments, other elements (not shown) are also included between the switch element T and the pixel electrode PE, but the invention is not limited thereto. In the present embodiment, the switching element T is described by taking the top gate type thin film transistor (TFT) as an example, but the present invention is not limited thereto. According to other embodiments, the above-mentioned switching element T may also be a bottom gate type TFT.

In the present embodiment, a light shielding layer SM is sandwiched between the switching element T and the substrate100. The light shielding layer SM is used to prevent the light from being irradiated on the channel CH of the switching element T and affecting the normal operation of the charge carrier in the switching element T, thereby preventing the leakage current from being generated. The material of the light-shielding layer SM may be selected from a material having a light-shielding effect, such as a metal, a metal compound (eg, silver halide), a resin, or other suitable materials.

The scan line SL and the data line DL intersect, and an interlayer dielectric layer130is sandwiched between the scan line SL and the data line DL. In this embodiment, it is assumed that the extending direction of the scan line SL is not parallel to the extending direction of the data line DL. A metal material is generally used for the scan line SL and the data line DL, but the present invention is not limited thereto. In other embodiments, the scan lines SL and the data lines DL may also use other conductive materials, such as a metal nitride, a metal oxide, a metal oxynitride, or other suitable conductive materials) or a stacked layer of a metal with other conductive materials.

The planarization layer140is located on the scan line SL, the data line DL, and the switching element T. The material of the planarization layer140comprises an inorganic material, an organic material, other suitable materials, or any combinations thereof. The inorganic material may be silicon oxide, silicon nitride, silicon oxynitride, other suitable materials, or a stacked layer of at least two materials above, for example. The organic material may be a polyester (PET), poly olefins, polyacryls, polycarbonates, polyalkylene oxides, polyphenylenes, polyethers, polyketones, polyalcohols, polyaldehydes, other suitable materials, or any combinations thereof.

The first common electrode CE1is located on the planarization layer140. The first common electrode CE1contacts a corner N1of the connecting portion CP. The first common electrodes CE1′ of other pixel structures around the pixel structure10contacts other corners of the connecting portion CP. The connecting portion CP overlaps a part of the data line DL. The connecting portion CP is, for example, integrally formed with the first common electrode CE1. For example, the connecting portion CP and the first common electrode CE1are patterned from the same film layer. A corner of the connecting portion CP contacts the first common electrode CE1.

The common line CL is located on the planarization layer140, and the first insulating layer150is located on the first common electrode CE1and the common line CL. The common line CL is directly connected with the first common electrode CE1. For example, the common line CL is in direct contact with the first common electrode CE1. After the common line CL is formed on the planarization layer140, the first common electrode CE1is formed on the common line CL and is in direct contact with the common line CE1. After that, a first insulating layer150is formed. The first insulating layer150covers the first common electrode CE1and the common line CL. In this embodiment, since the common line CL and the first common electrode CE1are not electrically connected by, for example, a contact bump or another through holes, the aperture ratio of the pixel structure10can be improved and the process yield of the picture structure can be improved. The common line CL is electrically connected to the connecting portion CP through the first common electrode CE1. The line width of the common line CL is W, and the width of the portion of the common line CL covered by the first common electrode CE1is W1, where 0<W1<W. The first common electrode CE1is, for example, covering a sidewall and a portion of the upper surface of the common line CL. In the present embodiment, at least one of the common line CL and the first common electrode CE1overlaps the data line DL. For example, the common line CL and the first common electrode CE1overlap with the data line DL, but the invention is not limited thereto.

The pixel electrode PE is located on the first insulating layer150. The first insulating layer150is sandwiched between the pixel electrode PE and the first common electrode CE1. The first contact hole V1penetrates the planarization layer140and the first insulating layer150. The pixel electrode PE is electrically connected to the drain D through the first contact hole V1. In the present embodiment, the pixel electrode PE and the data line DL are separated by the first common electrode CE1, so that the parasitic capacitance between the pixel electrode PE and the data line DL can be reduced to improve the flicker problem of the display device when the pixel structure is operated at low frequency.

The second insulating layer160is on the pixel electrode PE and the first insulating layer150.

The second common electrode CE2is located on the second insulating layer160. A second insulating layer160is sandwiched between the second common electrode CE2and the pixel electrode PE. The second contact hole V2penetrates the first insulating layer150and the second insulating layer160. The second common electrode CE2is electrically connected to the connecting portion CP through the second contact hole V2, and is electrically connected to the first common electrode CE1through the connecting portion CP. In this embodiment, the second common electrode CE2and the second contact hole V2are all overlapped with the data line DL, thereby reducing the influence of the second contact hole V2on the aperture ratio of the pixel structure10, but the present invention is not limited thereto. In this embodiment, the second common electrode CE2does not overlap with the first contact hole V1and through hole Vd, but the invention is not limited thereto. The second common electrode CE2has a plurality of slits H, and the slits H overlap the pixel electrode PE and the first common electrode CE1. In this embodiment, the second common electrode CE2and the first common electrode CE1respectively disposed above and below the pixel electrode PE enable the pixel structure10to have a larger effective area and further have larger storage capacitance, so that the flicker problem of the display device can be improved when the pixel structures operate at low frequencies. For example, supposing that the pixel structure10of the present embodiment is operated at a low frequency of 15 Hz and when Nth frame is displayed, the speed and amplitude of the decrease in brightness of the frame can be controlled to be smaller because of having a sufficiently large storage capacitance. When the next frame, that is, the N+1 th frame is displayed, the pixel structures are charged for display, the difference in brightness between the N+1th frame and the Nth frame is less noticeable, thereby reducing or eliminating the flicker phenomenon felt by human eyes.

In at least one embodiment of the present invention, the parasitic capacitance on the pixel electrode can be reduced and the storage capacitance can be increased, thereby improving the problem of the flicker of the display device when the pixel structure is operated at a low frequency.

FIG. 2Ais a top view of some components of a touch panel according to an embodiment of the invention.FIG. 2Bis a schematic top view of some components of a touch panel according to an embodiment of the present invention. It must be explained here that the embodiments ofFIGS. 2A and 2Bfollow the reference numerals and partial components of the embodiment ofFIGS. 1A to 1C, wherein the same or similar reference numerals are used to denote the same or similar components, and the descriptions of the same technical content are omitted. The omitted descriptions will not be repeated in the following embodiments, and may refer to the foregoing embodiment.

Please refer toFIG. 2AandFIG. 2B. For convenience of description,FIG. 2Aillustrates a first common electrode CE1, a second common electrode CE2, a connecting portion CP, a common line CL1, and a common line CL2in the pixel structures P1to P8, and other components are omitted.FIG. 2Billustrates the scan lines SL, the data lines DL, the pixel electrodes PE, and the second common electrode CE2of the pixel structures P1-P8, and the other components are omitted.

Please refer toFIG. 2AandFIG. 2B. The touch panel of this embodiment at least comprises a pixel structure P7and a pixel structure P1. In some embodiments, the touch panel further includes pixel structures P2-P6and P8. The plurality of scan lines SL and the plurality of data lines DL are interlaced with each other, and the structure of the pixel structures P1-P8is similar to the pixel structure10in the embodiment ofFIGS. 1A-1C.

The first common electrodes CE1of the pixel structures P1-P6are electrically connected to each other through connecting portions CP. The first common electrodes CE1of the pixel structures P7-P8are electrically connected to each other through the connecting portion CP. Referring toFIGS. 1A, 2A and 2Bat the same time, the connecting portion CP has corners N1, N2, N3, and N4. The corners N1, N2, N3, and N4of the connecting portion CP are respectively connected to the first common electrodes CE1of four adjacent pixel structures. In this embodiment, the two corners N2and N1of the connecting portion CP are respectively connected to the first common electrode CE1of the pixel structure P1and the first common electrode CE1of the pixel structure P4of the same column, and the other two corners N3and N4are respectively connected the first common electrode CE1of the pixel structure P2and the first common electrode CE1of the pixel structure P5of the other column. In this embodiment, a plurality of connecting portions CP are provided. A single connecting portion CP corresponds to four adjacent pixel structures and is electrically connected to the four adjacent pixel structures through the four corners N1, N2, N3, and N4of the connection portion CP, respectively, but the invention is not limited thereto. In the present embodiment, a single first common electrode CE1corresponds to four connecting portions CP. For example, a single first common electrode CE1is in contact with corners of four connecting portions CP, but not limited thereto. In this embodiment, the connecting portions CP are respectively overlapped with the intersections of the scanning lines SL and the data lines DL, but is not limited thereto.

In the present embodiment, each of the pixel structures P1and P4comprises the common line CL1, and each of the pixel structures P7and P8comprises the common line CL2. In this embodiment, each of the pixel structures P2, P3, P5, and P6does not comprise common line. Each of the pixel structures P2, P3, P5, and P6is electrically connected to the common line CL1through the first common electrode CE1of the pixel structure P1or the pixel structure P4, but the present invention is not limited thereto. In some embodiments, each of the pixel structures P2, P3, P5, and P6comprises common line CL1. The first common electrode CE1of each of the pixel structures P7and P8is electrically connected to the common line CL2.

In the present embodiment, the common line CL2of the pixel structure P7and the common line CL1of the pixel structure P1are separated from each other.

In the present embodiment, the pixel structure P4is adjacent to the pixel structure P1. The common line CL1of the pixel structure P4is directly connected to the common line CL1of the pixel structure P1.

In the present embodiment, since the common line CL1and the common line CL2are separated from each other, the first common electrodes CE1and/or the second common electrodes CE2of the pixel structures P1to P6and the first electrodes CE1and/or the second common electrodes CE2of the pixel structures P7to P8can be used as touch electrodes. In this embodiment, the common line CL1and/or the common line CL2can be made of a conductive material that is not easily deteriorated by heat, such as aluminum, titanium, molybdenum, magnesium, neodymium, silver, other suitable materials, or a combination of at least two of the above. In addition, the common line CL1and/or the common line CL2may be made of a low-reflective metal (eg, a blackened metal layer) to enhance optical performance. In various embodiments, a material of each of the first common electrode CE1, the second common electrode CE2, the connecting portion CP, and the pixel electrode PE is exemplified by a transparent conductive material such as indium tin oxide or indium zinc oxide. An LCD panel comprises the touch panel of at least one embodiment disclosed above, an opposite substrate and a liquid crystal layer. The liquid crystal layer is disposed between the touch panel and opposite substrate.

In at least one embodiment of the present invention, the parasitic capacitance can be reduced and the storage capacitance can be increased, thereby improving the problem of the screen flicker when the touch panel operates at low frequencies. The touch panel is provided to improve the flicker problem of the LCD panel operated at a low frequency.

In summary, in the pixel structure and the touch panel of the present invention, the first common electrode is in direct contact with the common line, the pixel electrode and the data line are separated by the first common electrode, and the second common electrode and the pixel electrode are structures of different layers. Therefore, the parasitic capacitance can be reduced and the storage capacitance can be increased, thereby improving the pixel structure and the flicker problem when the touch panel is operated at low frequencies.

Although the present invention has been disclosed by way of example above, it is not intended to limit the present invention. Any person of ordinary skill in the art can make some changes and changes without departing from the spirit and scope of the present invention. In the case of retouching, the scope of protection of the present invention shall be subject to the definition of the appended patent scope.