1. Field of the Invention
The present invention relates to a touch sensor integrated type display device, and more particularly, to a touch sensor integrated type display device capable of improving touch sensitivity while reducing the number of touch routing wires.
2. Discussion of the Related Art
In recent years, flat panel displays (hereinafter referred to as “display devices”), which are able to be manufactured as a large-sized display device at a low price and have high display quality (including capability of representing a motion picture, a resolution, brightness, a contrast ratio, a color representation capability, etc.), have been developed in accordance with the need for display devices capable of properly displaying the multimedia with the development of multimedia. Various input devices, such as a keyboard, a mouse, a track ball, a joystick, and a digitizer, have been used in the display devices to allow users to interface with the display devices.
However, when the user makes use of these input devices, the user's dissatisfaction increases because the user is required to learn how to use the input devices and the input devices occupy space, thereby having difficulty in increasing the perfection of products. Thus, a demand for a convenient and simple input device for the display device capable of reducing erroneous operations is increasing. In response to the increased demand, a touch sensor has been proposed to recognize information when the user inputs the information by directly touching the screen or approaching the screen with his or her hand or a pen while he or she watches the display device.
The touch sensor has a simple configuration capable of reducing the erroneous operations. The user can also perform an input action without using a separate input device and can quickly and easily manipulate a display device through the contents displayed on the screen. Thus, the touch sensor has been applied to various display devices.
The touch sensor used in display devices may be classified into an add-on type touch sensor, an on-cell type touch sensor, and an integrated type (or in-cell type) touch sensor depending on its structure. The add-on type touch sensor is configured such that the display device and a touch sensor module including the touch sensor are individually manufactured and then the touch sensor module is attached to an upper substrate of the display device. The on-cell type touch sensor is configured such that elements constituting the touch sensor are directly formed on the surface of an upper glass substrate of the display device. The in-cell type touch sensor is configured such that elements constituting the touch sensor are mounted inside the display device to thereby achieve thin profile of the display device and increase the durability of the display device.
Among the above touch sensors, because the in-cell type touch sensor may commonly use a common electrode of the display device as a touch electrode, a thickness of the display device is decreased as compared to the other touch sensors. Further, because the touch elements of the in-cell type touch sensor are formed inside the display device, the durability of the display device may increase. Hence, the in-cell type touch sensor has been widely used.
The in-cell type touch sensor can solve the problems generated in the add-on type touch sensor and the on-cell type touch sensor because of the advantages of the thin profile and the durability improvement. The in-cell type touch sensor may be divided into a light type touch sensor and a capacitive touch sensor depending on a method for sensing a touched portion. The capacitive touch sensor may be subdivided into a self capacitive touch sensor and a mutual capacitive touch sensor.
The self capacitive touch sensor forms a plurality of independent patterns in a touch area of a touch sensing panel and measures changes in a capacitance of each independent pattern, thereby deciding whether or not a touch operation is performed. The mutual capacitive touch sensor crosses X-axis electrode lines (for example, driving electrode lines) and Y-axis electrode lines (for example, sensing electrode lines) in a touch electrode formation area of a touch sensing panel to form a matrix, applies a driving pulse to the X-axis electrode lines, and senses changes in voltages generated in sensing nodes defined as crossings of the X-axis electrode lines and the Y-axis electrode lines through the Y-axis electrode lines, thereby deciding whether or not a touch operation is performed.
In the mutual capacitive touch sensor, a mutual capacitance generated in touch recognition of the mutual capacitive touch sensor is very small, but a parasitic capacitance between gate line and data lines constituting the display device is very large. Therefore, it is difficult to accurately recognize a touch position because of the parasitic capacitance.
Further, because a plurality of touch driving lines for a touch drive and a plurality of touch sensing lines for a touch sensing have to be formed on the common electrode for the multi-touch recognition of the mutual capacitive touch sensor, the mutual capacitive touch sensor requires a very complex line structure.
On the other hand, because the self capacitive touch sensor has a simpler line structure than the mutual capacitive touch sensor, touch accuracy may increase. Hence, the self capacitive touch sensor has been widely used, if necessary or desired.
A related art liquid crystal display (hereinafter referred to as “touch sensor integrated type display device”), in which a self capacitive touch sensor is embedded, is described below with reference to FIG. 1. FIG. 1 is a plane view of a related art touch sensor integrated type display device.
As shown in FIG. 1, the touch sensor integrated type display device includes an active area AA, in which touch electrodes are formed and data is displayed, and a bezel area BA positioned outside the active area AA. In the bezel area BA, various wires and a touch integrated circuit (IC) 10 are formed.
The active area AA includes a plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 divided in a first direction (for example, x-axis direction) and a second direction (for example, y-axis direction) crossing the first direction and a plurality of touch routing wires TW11-TW14, TW21-TW24, TW31-TW34, TW41-TW44, and TW51-TW54, which are respectively connected to the plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 and are arranged in parallel with one another in the second direction.
The plurality of touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54 inside the active area AA are formed by dividing a common electrode of the display device, and thus operate as common electrodes in a display drive for displaying data and operate as touch electrodes in a touch drive for recognizing a touch position.
The bezel area BA positioned outside the active area AA includes the touch IC 10 and various wires. In the display drive, a driving IC for the display device and the touch IC 10 drive gate lines (not shown) of the display device, supply display data to data lines (not shown), and supply a common voltage to the touch electrodes (or the common electrodes). In the touch drive, the touch IC 10 supplies a touch driving voltage to the touch electrodes and scans changes in a capacitance of each touch electrode before and after a touch operation, thereby determining a position of the touched touch electrode. The various wires include the touch routing wires TW11-TW14, TW21-TW24, TW31-TW34, TW41-TW44, and TW51-TW54 connected to the touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54, the gate lines connected to the touch IC 10, and the data lines.
The related art touch sensor integrated type display device respectively connects the touch routing wires TW11-TW14, TW21-TW24, TW31-TW34, TW41-TW44, and TW51-TW54 to the touch electrodes Tx11-Tx14, Tx21-Tx24, Tx31-Tx34, Tx41-Tx44, and Tx51-T54. Thus, because one touch routing wire has to be connected to each touch electrode, the number of touch routing wires increases as the size of the display device becomes larger. For example, when touch electrodes each having a pitch of 4.3 mm are disposed in a 15.6-inch display device, about 80 touch electrodes of one line in a horizontal direction and about 45 touch electrodes of one line in a vertical direction are required. As a result, the total number of touch electrodes is about 3600, and the 3600 touch electrodes are connected to the touch IC 10 through 3600 touch routing wires, respectively. Because the touch IC 10 includes a circuit for driving each touch electrode, the manufacturing cost of the display device increases as the size of the touch IC 10 becomes larger.
Furthermore, when the number of touch routing wires increases as the size of the display device becomes larger, a parasitic capacitance between the touch routing wires and the gate and data lines of the display device increases. Hence, the touch sensitivity is reduced.