JP3449361B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a matrix type liquid crystal display device using thin film transistors, which prevents device breakdown due to abnormally high voltage due to static electricity or the like, and degrades performance and productivity. It is intended to improve the yield and the yield. 2. Description of the Related Art A liquid crystal display device is based on a glass substrate.
A conductive film and an insulating film are sequentially formed on the surface, and a pattern is formed using a photoresist as a mask. In the manufacturing process, charging due to static electricity or the like is likely to occur, and an abnormally high voltage (hereinafter referred to as a surge voltage). ), Which causes the destruction of the thin film transistor constituting the pixel and the damage of the wiring. Therefore, in the conventional liquid crystal display device, the video signal wiring group 3 and the scanning signal wiring group 5 are connected on the outer periphery of the liquid crystal display panel 1, as shown in FIG. As a result, even if a surge voltage due to static electricity or the like is generated in the liquid crystal display panel manufacturing process, the influence is not concentrated on a specific video signal wiring or scanning signal wiring, but is dispersed over the entire screen. 7, does not cause destructive damage to the liquid crystal cell 8, the storage capacitor 9, and the like. For example, if the charge of Q0 flows into only a specific scanning signal line from the outside due to static electricity, and the capacitance per line of the scanning signal line is Cg0, then the following equation is obtained: Vg1 = Q0 / Cg0 The voltage Vg1 is specified. Is applied to the scanning signal lines, but when the scanning signal line group is connected as described above,
The capacitance of the scanning signal wiring group is multiplied by the number of scanning signal wirings (N lines) of the capacitance per line (Cg0), and as follows: Vgall = Q0 / N × Cg0 = Vg1 / N Voltage Vgall Is applied. This is the N of the voltage Vg1.
This is one-half, and the applied voltage can be reduced and the element can be prevented from being destroyed. However, in the state where the video signal wiring and the scanning signal wiring are connected as in the above configuration, it is impossible to display an image. When the liquid crystal display panel is cut out from the substrate, the connection of the video signal wiring group and the scanning signal wiring group is cut off at the same time and separated into respective wirings. Therefore, in the subsequent steps, for example, the inspection step of the liquid crystal display panel and the mounting step of the external drive circuit, the problem of application of surge voltage due to static electricity or the like and the problem of element destruction cannot be solved. It is an object of the present invention to provide a surge protection circuit for preventing a liquid crystal display panel from being damaged by application of a surge voltage after a video signal wiring or a scanning signal wiring is separated. According to the present invention, there is provided a pixel region including a plurality of pixel electrodes, a scanning signal wiring group, a video signal wiring group, and one end provided with the scanning signal wiring. Or, a plurality of high resistance elements or a plurality of non-linear voltage / current elements connected to the video signal wiring, a common wiring to which the other end of the high resistance element or the non-linear voltage / current element is connected, the pixel electrode or the image a counter electrode that forms a capacitance between the signal wiring or the scanning signal lines, before
The point at which the common wiring and the counter electrode are connected is
The common line and the high-resistance element or the non-linear voltage / current element are arranged outside the pixel region and in a region inside the end of the scanning signal line group and the end of the video signal line group. it is to produce a liquid crystal display panel, a manufacturing method of a liquid crystal display device, characterized in that detach the points after mounting the external drive circuit to the liquid crystal panel. [0008] The common wiring is cut off from an electrode forming a capacitor between the pixel electrode and the video signal wiring or the scanning signal wiring after the external drive circuit mounting step. By using the means of the present invention, it is possible to reduce a surge voltage intruding from a video signal wiring or a scanning signal wiring, suppress the destruction of elements and wirings inside pixels, and improve the yield. Further, after the external drive circuit is mounted, the surge protection circuit can be cut off from the common wiring to reduce leakage current and power consumption. An embodiment of the present invention will be described below. FIG.
FIG. 1 shows a schematic diagram of a configuration of a liquid crystal display device according to an embodiment of the present invention. The same parts as in FIG. 3 of the conventional example are denoted by the same reference numerals. As shown in FIG. 1, the scanning signal wiring 6 connected to the gate electrode of the thin film transistor 7 in the pixel region 2,
The video signal wiring 4 connected to the source electrode of the thin film transistor 7
And a common line 11 connected to a counter electrode 10 forming a large capacitance between the pixel electrode 9 or the video signal line 4 or the scanning signal line 6 connected to the source electrode. These intersections, the surge protection circuit 14 which is connected to the drain electrode to each other of the TFT 12 connected to thin film transistors 13 and the source electrode and the gate electrode to the scanning signal No. wiring 6 run the source electrode and gate electrode connected to the common wiring 11 Is composed. These thin film transistors 12 and 13 are:
Since the source electrode and the gate electrode are shared, the diode has a diode voltage-current characteristic as shown in FIG. That is,
When the applied voltage is lower than the voltage Vb, the current rapidly increases, and exhibits a reverse characteristic in which the conductive state is established. Usually, this voltage Vb is higher than the drive signal voltage of the liquid crystal display device and is several tens of volts or more. Therefore, during normal pixel display, almost no current flows through the surge protection circuit 14 and the video signal wiring 4
And the scanning signal wiring 6 and the common wiring 11 are insulated, but when a surge voltage of several tens of volts or more is applied,
A current flows through the surge protection circuit 14, the video signal wiring 4 and the scanning signal wiring 6 and the common wiring 11 become conductive, the surge voltage is absorbed by the counter electrode 10, and no high voltage is applied to the elements inside the pixel. By the way, the surge voltage applied to the liquid crystal display panel during the manufacture of the liquid crystal display device does not directly enter after the external drive circuit mounting step. Further, if the surge protection circuit 14 is provided between the video signal wiring 4 and the scanning signal wiring 6 and the common wiring 11, a small amount of current flows. In particular, when the backlight is turned on, a rise in light or temperature causes an increase in the leak current of the surge protection circuit 14, which causes a fluctuation in the potential of the counter electrode and an increase in power consumption. Therefore, the surge protection circuit 14 is disconnected from the common wiring 11 at the point 15 after the external drive circuit mounting process or after module assembly in which no surge voltage is applied to the liquid crystal display panel, so that the current does not flow into the common wiring 11. In this embodiment, the thin film transistor constituting the surge protection circuit 14 has the same structure as the thin film transistor in the pixel, and has an advantage that it can be easily formed. A diode using a PN junction does not matter at all. This method of manufacturing a liquid crystal display device is more effective when the surge protection circuit 14 is formed of a high resistance element or a diode ring. As described above, the present invention suppresses the surge voltage applied to the liquid crystal display device, prevents damage to the thin film transistor, the capacitor, or the wiring in the pixel region, and improves the yield. I do. Further, since the reverse characteristics of the diode are used, unnecessary current does not flow, interference between the electrodes is suppressed, and power consumption is not increased. Further, by disconnecting the surge protection circuit from the common wiring, the influence of the leakage current can be completely eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a diagram of a diode voltage-current characteristic of the embodiment. FIG. Schematic diagram [Description of symbols] 1 Liquid crystal display panel 2 Pixel region 3 Video signal wiring group 4 Video signal wiring 5 Scanning signal wiring group 6 Scanning signal wiring 7 Thin film transistor 8 Liquid crystal cell 9 Pixel electrode 10 Counter electrode 11 Common wiring 12, 13 Thin film transistor (Common to source electrode and gate electrode) 14 Surge protection circuit 15 Common wiring disconnection point

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-296725 (JP, A) JP-A-2-242229 (JP, A) JP-A-63-106788 (JP, A) JP-A-5-205 333377 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/136

Claims (1)

(57) [Claim 1] A pixel region including a plurality of pixel electrodes, a scanning signal wiring group, a video signal wiring group, and one end connected to the scanning signal wiring or the video signal wiring. A plurality of high resistance elements or a plurality of nonlinear voltage / current elements, a common wiring to which the other end of the high resistance element or the non-linear voltage / current element is connected, the pixel electrode or the video signal wiring or the scanning signal wiring, A counter electrode forming a capacitor between the common wiring and the point where the common electrode and the counter electrode are connected;
The common wiring and the high-resistance element or the non-linear voltage / current element are provided outside the pixel region and in an area inside an end of the scanning signal wiring group and an end of the video signal wiring group. method of manufacturing a liquid crystal display device manufactured arranged liquid crystal display panel, and wherein said to detach the points after mounting the external drive circuit to the liquid crystal panel.