JP4951841B2 - LCD panel - Google Patents

Description

  The present invention relates to a liquid crystal panel used for a liquid crystal display device and the like, and in particular, in an active matrix type liquid crystal panel in which an active element is attached to each display element, the destruction of the active element due to static electricity during the manufacturing process is prevented. The present invention relates to a liquid crystal panel with a protection circuit.

  The liquid crystal panel of the liquid crystal display device includes a simple matrix type and an active matrix type, but due to high definition of the liquid crystal display device, the simple matrix type has a crosstalk. Since an image contrast is deteriorated, an active matrix type liquid crystal panel in which a switching element such as a thin film transistor or a thin film diode is provided for each pixel is frequently used to prevent this.

  In an active matrix type liquid crystal panel using a pixel in which an active element such as a thin film transistor or a thin film diode is attached to each display element, the active element is intruded from outside during the manufacturing process or due to static electricity generated in the liquid crystal panel. As a result, the scanning lines or video lines that are electrically independent generate a short circuit between each other.

  For example, in a process of processing a liquid crystal display panel, a TFT substrate is placed on an exposure stage and a predetermined processing operation such as exposure is performed. In the process of aligning the TFT substrate on the exposure stage, etc. Then, static electricity is generated by friction between the TFT substrate made of a glass substrate and the exposure stage. In addition, peeling electrification occurs when the TFT substrate is moved from the exposure stage by the conveying means after the exposure is completed. At this time, the charged static electricity increases and sparks, and electrostatic breakdown occurs that destroys the element formed on the substrate.

  Such electrostatic breakdown due to a short circuit between wirings may cause a line defect or a point defect on the display screen, which greatly affects the manufacturing yield of the liquid crystal display device. Therefore, as a measure to prevent electrostatic breakdown of the thin film transistor, an outer short ring that will be separated from each wiring later is provided on the outer periphery of the liquid crystal panel wiring, and each wiring is connected to the outer short ring to distribute static electricity to each wiring. In other words, a method of relaxing the voltage between the scanning line and the video line has been used.

  However, in the case of the outer short ring, it is cut off in the cutting process of the substrate, and after the outer short ring is cut off, the liquid crystal panel has nothing to prevent the electrostatic breakdown of the thin film transistor. Measures against static electricity after cutting the outer short ring became a problem. Therefore, as in the invention of Patent Document 1 shown in FIG. 5, an inner short ring E is provided so as to take measures against static electricity even after the outer short ring is cut, and each wiring is connected to the inner short ring E via a protection transistor. It has been proposed (see Patent Document 1).

  Further, as shown in FIG. 6, the scanning line and the video line are connected to the respective short-circuit wirings 160 and 170 via the respective antistatic circuits 120 and 130, and the scanning line and the video line are further short-circuited. In some cases, the scanning line short-circuit wiring 160 is connected to the bars 100 and 110, and the scanning voltage minimum voltage Vg1 is applied to the video line short-circuiting wiring 170 and the stable common voltage Vcom is applied to the video line short-circuiting wiring 170 (see Patent Document 2). ).

  However, according to the invention disclosed in Patent Document 1, each wiring connected to the ground wire is connected to the inner short ring via a protection transistor as a countermeasure against electrostatic breakdown. There is a problem in that power consumption increases because current flows between the wires.

In the case of the invention disclosed in Patent Document 2, each of the scanning line and the video line is doubly connected, the inside is connected to the short-circuit wiring via the antistatic circuit, and the outside is connected to the short bar. After disconnecting the outer short bar, there was a problem that the power consumption was large due to the leakage current.
Japanese Patent Laid-Open No. 63-10558 (page 2 to page 3, FIG. 1) Japanese Patent Laid-Open No. 10-303431 (pages 5-6, FIG. 7)

  In contrast, the present inventors formed an inner short ring to prevent electrostatic breakdown, connected the scanning line and the video line, and connected this to the common potential line formed on the array side of the array substrate. It was. The potential of the common potential line is the same as that applied to the counter electrode of the color filter substrate, and is connected to the counter electrode at the four corners of the substrate.

However, in this case, there is a problem that power consumption increases.
In other words, each wiring connected to the counter electrode remains connected to the inner short ring via the transistor as a countermeasure against electrostatic breakdown. However, if it remains connected to the common potential line, a current flows between the common potential line and each scanning line or video line, particularly the scanning line. This is because, as shown in the voltage waveform diagram during driving of the liquid crystal display device in FIG. 1, the voltage Voff is always applied to the scanning line even when it is not scanned, and the voltage Von is applied when scanned. This is because the potential difference between the common potential line and the voltage applied to the scanning line is large. Since the voltage applied to the scanning line is larger than the voltage applied to the video line, the current flowing between the scanning line and the common potential line is increased. Therefore, since the power consumption of the liquid crystal panel is increased, there is a demand for a liquid crystal panel with less power consumption.

  As a result of various studies to solve the above problems, the inventor of the present application bundled the scanning line and the video line to which the transistor for electrostatic breakdown countermeasures was connected with each short-circuit line, and then each short-circuit line. By connecting each wiring bundled together in the inner short ring via a transistor, it is possible to suppress the leakage current generated between each wiring and the inner short ring, thereby providing a liquid crystal panel with low power consumption. The present invention has been completed by paying attention to the fact that this is possible.

  That is, an object of the present invention is to provide a liquid crystal panel with low power consumption in a liquid crystal panel provided with a protection circuit against electrostatic breakdown, and to solve the above-mentioned problems. An active matrix type liquid crystal panel is related to a liquid crystal panel with a protection circuit that prevents the active element from being destroyed by static electricity during the manufacturing process, and is intended to provide a liquid crystal panel that is strong against electrostatic damage and consumes little power. Is.

  In order to solve the above problem, the invention according to claim 1 of the present application is a liquid crystal in which each pixel is configured by arranging a liquid crystal display element and a thin film transistor in each region surrounded by scanning lines and video lines arranged in a matrix. In the panel, a first electrostatic protection circuit is connected to each scanning line, the scanning lines are bundled with a short-circuit line, and the scanning line bundled with the short-circuit line and a common potential line are connected, It is characterized in that at least the scanning line and the common potential line among the scanning line and the common potential line bundled by a short circuit line are connected via a second electrostatic protection circuit.

  In the liquid crystal panel according to the present invention, the common potential line is provided on the array substrate, and the counter electrode of the color filter substrate is connected to any one of the four corners of the array substrate.

  In the liquid crystal panel of the invention according to the present invention, a first electrostatic protection circuit is connected to each of the video lines, and the video lines are bundled with a short-circuit line, and are shared with the video lines bundled with the short-circuit line. A potential line is connected, and at least between the scanning line and the common potential line among the video line and the common potential line bundled by the short-circuit line is connected via a second electrostatic protection circuit. It is connected.

  In the liquid crystal panel according to the present invention, it is preferable that the first and second electrostatic protection circuits are formed of diodes connected in parallel in which anodes and cathodes of two diodes are connected to each other.

  In the liquid crystal panel according to the present invention, the first and second electrostatic protection circuits are preferably parallel circuits in which two transistors whose gates and sources are short-circuited are connected in opposite directions. .

  In the liquid crystal panel of the invention according to the present invention, it is preferable that the second electrostatic protection circuit is composed of a non-linear resistance element.

  In the invention according to claim 7, which is the second embodiment of the present invention, each pixel is configured by arranging a liquid crystal display element and a thin film transistor in each region surrounded by scanning lines and video lines arranged in a matrix. In the liquid crystal panel, a first electrostatic protection circuit composed of two nonlinear resistance elements connected in parallel to each scanning line and each video line in the reverse direction is connected, and each scanning line and each video line are short-circuited. The scanning line and the video line that are bundled by the short-circuit line are connected to a common potential, and at least one of the scanning line or the video line and the common potential is parallel in the opposite direction. The connection is made through a second electrostatic protection circuit composed of two connected non-linear resistance elements.

  In the liquid crystal panel according to the present invention, the common potential line is provided on the array substrate, and the counter electrode of the color filter substrate is the second electrostatic protection circuit connected at one of the four corners of the array substrate. It is characterized by being.

  In the liquid crystal panel of the invention according to the present invention, the first and second electrostatic protection circuits are preferably formed of diodes connected in parallel in which anodes and cathodes of two diodes are connected to each other.

  In the liquid crystal panel according to the present invention, the first and second electrostatic protection circuits may be parallel circuits in which two transistors whose gates and sources are short-circuited are connected in opposite directions. preferable.

  According to the first or second or seventh aspect of the present invention, it is possible to provide a liquid crystal panel that has a simple configuration, is strong against electrostatic breakdown, and consumes less power.

  Further, according to the invention according to claim 3 or claim 8, it is possible to provide a liquid crystal panel that can be connected to a common potential with a simple configuration, is strong against electrostatic breakdown, and consumes less power. .

  Further, according to the inventions according to claims 4 to 6 or claims 9 to 10, since the electrostatic protection circuit can be formed in the same process as the manufacture of the thin film transistor, a liquid crystal panel which is strong against electrostatic breakdown and has low power consumption. The manufacturing process can be provided without any special changes.

  Hereinafter, a liquid crystal panel according to the present invention will be described in detail with reference to the accompanying drawings. That is, the above object of the present invention can be achieved by one aspect of the present invention having the following configuration.

  In the liquid crystal panel of an active matrix type liquid crystal display device, one of the two substrates made of glass or the like disposed opposite to each other with the liquid crystal layer interposed between them extends on the surface on the liquid crystal layer side of one substrate in the X direction. And a plurality of scanning lines arranged in the Y direction and a plurality of video lines insulated from the scanning lines and extending in the Y direction and arranged in the X direction.

  As shown in FIG. 2, in the liquid crystal panel 10, each region surrounded by the scanning lines 11 and the video lines 12 arranged in a matrix is a pixel region, and for example, a thin film transistor 13 is used as a switching element in the pixel region. Further, a thin film diode and a transparent pixel electrode 14 are formed to constitute a liquid crystal display element. In the figure, the gate electrode of the thin film transistor 13 which is a switching element is connected to the scanning line 11, the drain electrode is connected to the video line 12, and the source electrode is connected to the transparent pixel electrode 14, respectively. In such a configuration, when the scanning signal is supplied to the scanning line 11, the thin film transistor 13 is turned on, and the video signal from the video line 12 is supplied to the pixel electrode 14 through the turned on thin film transistor.

  In the liquid crystal panel 10 according to the present invention, the first electrostatic protection circuits 151 and 152 are connected to the scanning lines 11 and the video lines 12, and the scanning lines 11 and the video lines 12 are bundled together by the short-circuit lines 161 and 162, respectively. The scanning lines 11 and the video lines 12 bundled with the short-circuit lines 161 and 162 are connected to the common potential line (earth) 17. In addition, at least between the scanning line 11 and the common potential line 17 among the scanning line 11 or the video line 12 bundled with the short-circuit lines 161 and 162 and the common potential line 17, the second electrostatic protection circuit 181 is interposed. Connected.

  Here, the common potential line 17 is an electrode provided on the array substrate of the liquid crystal panel, and is connected to the counter electrode of the color filter substrate at any of the four corners of the array substrate. As a result, the second electrostatic protection line is provided. The circuits 181 and 182 are also connected.

  By the way, in the liquid crystal panel of the invention according to the present invention, the first electrostatic protection circuits 151 and 152 and the second electrostatic protection circuits 181 and 182 are each composed of a non-linear resistance element. A parallel circuit in which two diodes in which the anode and the cathode are connected in parallel or two transistors in which the gate and the source are short-circuited are connected in opposite directions is preferable.

  That is, as shown in FIG. 3, the first electrostatic protection circuits 151 and 152 and the second electrostatic protection circuits 181 and 182 have a non-linear current − in which two diodes 31 and 32 are arranged in parallel in opposite directions. It is composed of a non-linear resistance element having voltage characteristics. FIG. 4 shows a configuration in which two thin film transistors in which the gate and the source are short-circuited instead of the two diodes in FIG.

  In the electrostatic protection circuit of FIG. 4, this circuit comprises a first thin film transistor 41 and a second thin film transistor 42 whose sources and drains are connected to each other. The first thin film transistor 41 is connected to a first gate connected to the scanning line 11, a first source connected to the first gate and a second drain of the second thin film transistor 42, and a second source of the second thin film transistor 42. Including a first drain; The second thin film transistor has a second gate connected to the scanning line on the opposite side of the first gate, a second source connected to the second gate and the first drain of the first thin film transistor, and a first source of the first thin film transistor. A second drain formed.

  Since the first and second electrostatic protection circuits formed by such elements can be formed by the same manufacturing process as the thin film transistor 13 of the matrix array of the liquid crystal panel, it is not necessary to take a special manufacturing method.

  The first electrostatic protection circuits 151 and 152 and the second electrostatic protection circuits 181 and 182 are a parallel circuit of diodes connected in parallel in opposite directions in which anodes and cathodes of two diodes are connected to each other, Since it is a parallel circuit in which two transistors with their sources short-circuited are connected in opposite directions, even if a high voltage such as static electricity with different positive and negative polarities is applied, it turns on with either diode or positive bias Either the protection transistor or the protection transistor turned on with a negative bias is turned on, the high voltage is conducted to the ground, the thin film transistor as the active element is protected, and electrostatic breakdown can be prevented.

  Further, before the array test, each wiring is short-circuited by an outer short ring (not shown), so that it is protected from static electricity. After the array test, after the liquid crystal panel is separated from the outer short ring, the double electrostatic protection circuits 151, 152 and 181 and 182 connected to the short-circuit lines 161 and 162 and the common potential line 17 are used to Occurrence of fluctuations in the threshold voltage Vth and the like are prevented.

  On the other hand, the power consumption is such that the scanning line 11 and the video line 12 are connected to the common potential line 17 through the diodes and thin film transistors of the second electrostatic protection circuits 181 and 182 by bundling the wirings. As a result, current hardly flows between the bundle of wirings and the common potential line 17, thereby suppressing leakage current to the common potential line 17 and obtaining a liquid crystal panel with low power consumption.

  When only the scanning line 11 or the video line 12 is connected to the common potential line 17 via the second electrostatic protection circuit 181 or 182, the voltage applied to the scanning line compared to the voltage applied to the video line. Therefore, the current flowing between the scanning line and the common potential line is large, and the effect of reducing the power consumption is greater when the second electrostatic protection circuit 181 is connected to the scanning line 11. Therefore, in the present invention, it is necessary to connect at least the scanning line 11 to the common potential line 17 via the second electrostatic protection circuit 181.

  In the above description, the common potential is not limited to the common potential including the ground.

  The embodiments of the present invention have been described above with reference to the drawings. However, what has been described above exemplifies an example for embodying the technical idea of the present invention, and is not intended to specify the present invention in this embodiment, and does not depart from the gist thereof. Various changes can be made in the range, and the present invention can be equally applied to the modified examples.

It is a voltage waveform figure at the time of the drive of a liquid crystal display device. FIG. 2 is an explanatory diagram of an embodiment of a liquid crystal panel according to the present invention. 1 is a circuit diagram of an electrostatic protection circuit according to the present invention. It is a circuit diagram of the other electrostatic protection circuit which concerns on this invention. It is a top view of the conventional liquid crystal display device. It is a circuit block diagram of the other conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal panel 11 Scan line 12 Video line 13 Thin-film transistor 14 Transparent pixel electrode 151,152 1st electrostatic protection circuit 161,162 Short circuit line 17 Common electric potential line 181,182 2nd electrostatic protection circuit

Claims (1)

A plurality of scanning lines and a plurality of video lines are arranged in a matrix, the plurality of pixels by arranging a liquid crystal display device and a thin film transistor in each region surrounded by the respective each said plurality of video lines of the scanning lines In the liquid crystal panel that
A first electrostatic protection circuit is connected to one end of each of the plurality of scanning lines, and all of the plurality of scanning lines are respectively connected to one scanning line side short-circuit line via the first electrostatic protection circuit. ,
A first electrostatic protection circuit is connected to one end of each of the plurality of video lines, and all of the plurality of video lines are respectively connected to one video line side short-circuit line via the first electrostatic protection circuit. ,
The first static electricity protection circuit of the scanning line and the first static electricity protection circuit of the video line are arranged so that two thin film transistors whose gates and sources are short-circuited are connected to each other. It consists of a parallel circuit
Of the two thin film transistors, the gate of one thin film transistor is connected to each scanning line or each video line, and the gate of the other thin film transistor is connected to the short circuit line,
A common potential line connected to the counter electrode of the color filter substrate and one of the four corners of the array substrate is provided on the array substrate,
A second electrostatic protection circuit is connected to the scanning line side short circuit line, and the scanning line side short circuit line is connected to the common potential line via the second electrostatic protection circuit;
A second electrostatic protection circuit is connected to the video line short circuit line, and the video line short circuit line is connected to the common potential line via the second electrostatic protection circuit;
The second static electricity protection circuit of the scanning line side short-circuit line and the second static electricity protection circuit of the video line side short-circuit line include two thin film transistors in which a gate and a source are short-circuited with each other as a source and a drain. Is composed of parallel circuits arranged so as to connect,
Of the two thin film transistors, the gate of one thin film transistor is connected to the scanning line side short-circuit line or the video line side short-circuit line, and the gate of the other thin film transistor is connected to the common potential line. LCD panel.

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