CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese application JP 2019-036038, filed on Feb. 28, 2019 and Japanese application JP 2019-062863, filed on Mar. 28, 2019. These Japanese applications are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an active matrix substrate, a liquid crystal display device, and an in-cell touch panel.

A display device such as a liquid crystal display device or an organic electro luminescence (EL) display device includes a thin film transistor substrate (hereinafter referred to as the “TFT substrate”) provided with a thin film transistor (TFT).

In particular, in an active-matrix-drive display device, an active matrix substrate where a TFT is provided for each pixel in an image display region is used as the TFT substrate. For example, the active-matrix-drive liquid crystal display device is provided with a TFT substrate being an active matrix substrate, a counter substrate facing the TFT substrate, and a liquid crystal layer disposed between the TFT substrate and the counter substrate.

In the image display region of the TFT substrate, other than the TFT, a gate line and a data line are provided as signal lines. Further, a gate driver that supplies a gate signal to the gate line and a source driver that supplies a video signal to the data line are mounted on the TFT substrate.

Examples of a method for mounting the gate driver and the source driver include a chip on film (COF) method in which a tape carrier package (TCP) having the gate driver and source driver mounted on a flexible wiring board is connected to the frame region of the TFT substrate, and a chip on glass (COG) method in which the gate driver and the source driver are directly mounted on the TFT substrate. For this reason, the frame region of the TFT substrate is provided with a gate terminal electrically connected to the gate driver and a source terminal connected to the source driver. The gate terminal connected to the gate driver is electrically connected to a gate line provided in the image display region. Similarly, the source terminal connected to the source driver is electrically connected to a data line provided in the image display region.

In recent years, in-cell liquid crystal display devices (in-cell touch panels) having a touch function as well as a display function have been developed. In the image display region of the in-cell touch panel, a touch line for detecting a touch position is provided as a signal line in addition to the gate line and the data line. For this reason, a touch terminal electrically connected to the touch line is also provided in the terminal portion of the frame region in the TFT substrate of the in-cell touch panel.

The terminals provided in the terminal portion of the frame region each have a metal layer electrically connected to a signal line provided in the image display region. The metal layer is made of a metal material such as copper. Further, the terminals have exposed portions that are exposed to the outside so as to be electrically connected to the driver. In this case, when the metal layer is exposed, the metal layer deteriorates. Thus, for protecting the metal layer, there has been proposed a technique in which an indium tin oxide (ITO) film being the same layer as the pixel electrode is used and the metal layer is covered with the ITO film (e.g., International Publication No. 2017/213180).

SUMMARY

However, there is a problem with the above technique in that simply covering the metal layer of the terminal with the ITO film cannot sufficiently protect the metal layer, and the metal layer corrodes.

Also, there is a problem with the in-cell touch panel in that it is difficult to facilitate the connection of a plurality of touch lines to the terminal portion without expanding the frame region.

A first object of the present disclosure provides an active matrix substrate and a liquid crystal display device that can inhibit corrosion of a metal layer of a terminal electrically connected to a signal line in an image display region.

A second object of the present disclosure provides an in-cell touch panel that can easily connect a plurality of touch lines to a terminal portion without expanding a frame region.

To solve the first object of the present disclosure, an active matrix substrate according to a first present disclosure has an image display region made up of a plurality of pixels, and a frame region surrounding the image display region. The active matrix substrate includes: a pixel electrode provided in each of the plurality of pixels; a common electrode facing one or more of the pixel electrodes; a signal line provided in the image display region; and a terminal provided in the frame region and electrically connected to the signal line. The terminal includes a metal layer, a first contact layer located closer to one side in a lamination direction than the metal layer, and electrically connected to the metal layer, a first interlayer insulating layer located closer to the one side in the lamination direction than the first contact layer, and a second contact layer located closer to the one side in the lamination direction than the first interlayer insulating layer, and electrically connected to the first contact layer through a first through-hole formed in the first interlayer insulating layer. The first contact layer is made of a transparent metal oxide or a semiconductor material doped with impurities.

A liquid crystal display device according to a present disclosure includes the active matrix substrate according to the first present disclosure.

In the liquid crystal display device according to the present disclosure, an end of the first touch relay wiring and an end of the second touch relay wiring may be located below the terminal portion, the end of the first touch relay wiring and the first touch terminal electrode may be connected through a first contact hole, and the end of the second touch relay wiring and the second touch terminal electrode may be connected through a second contact hole.

In the liquid crystal display device according to the present disclosure, the number of the first contact holes and the number of the second contact holes may be more than one.

In the liquid crystal display device according to the present disclosure, the first touch terminal electrode and the second touch terminal electrode may be formed in the same layer as the pixel electrodes.

In the liquid crystal display device according to the present disclosure, the end of the first touch relay wiring and the first touch terminal electrode may be connected via a first relay electrode formed in the first contact hole, the end of the second touch relay wiring and the second touch terminal electrode may be connected through a second relay electrode formed in the second contact hole, and the first relay electrode and the second relay electrode may be formed in the same layer as the common electrode in a layer below the pixel electrode.

In the liquid crystal display device according to the present disclosure, the terminal portion may further include a plurality of source terminal electrodes electrically connected to the plurality of data lines, each of the plurality of source terminal electrodes may be electrically connected to each of the plurality of data lines via source relay wiring, and the source relay wiring may be formed in a different layer from the data line.

To solve the second object of the present disclosure, an in-cell touch panel according to a second present disclosure has an image display region and a frame region, the image display region being made up of a plurality of pixels arranged in a first direction and a second direction orthogonal to the first direction, the frame region surrounding the image display region, the in-cell touch panel comprising: a transistor and a pixel electrode provided in each of the plurality of pixels; a plurality of common electrodes arranged in each of the first direction and the second direction, each facing one or more of the pixel electrodes, and provided separately from each other; a plurality of gate lines that extend along the first direction and each supply a gate signal to the transistor in each of the plurality of pixels; a plurality of data lines that extend along the second direction and each supply a data signal to the transistor in each of the plurality of pixels; a plurality of touch lines that extend along the second direction and are each connected to a corresponding common electrode; and a terminal portion provided in the frame region and including a plurality of touch terminal electrodes electrically connected to the plurality of touch lines, wherein the plurality of touch lines include a first touch line and a second touch line, the plurality of touch terminal electrodes include a first touch terminal electrode electrically connected to the first touch line via first touch relay wiring, and a second touch terminal electrode electrically connected to the second touch line via second touch relay wiring, the first touch relay wiring has a first relay wiring portion formed in a different layer from the first touch line and the first touch terminal electrode, and the second touch relay wiring includes a first relay wiring portion formed in a different layer from the second touch line and the second touch terminal electrode and formed in a different layer from the first relay wiring portion of the first touch relay wiring.

