Liquid crystal display device

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to, for example, an active matrix type liquid crystal display panel and a liquid crystal display device including a data driver having a bus line for inputting an analog data signal such as a video signal to the liquid crystal display panel.

【0002】

[Conventional technology]

Conventionally, the liquid crystal display device described above is known to be configured as shown in FIG. This liquid crystal display device includes a liquid crystal display panel 31 and a data driver 30, and the data driver 30 includes a shift register circuit 1 and a plurality of shift register output bus lines 2 having one end connected to the shift register circuit 1. .. A thin film transistor 7 which is an analog switch is connected to the other end of each shift register output bus line 2.

【0003】

Each thin film transistor 7 is turned on and off between two terminals by control by an output signal from the shift register circuit 1. One of the R, G, B video signal input bus lines 3, 4, and 5 is connected to one of the two terminals via the analog switch input bus line 6, and a sampling capacitor is connected to the other terminal. 8 and the display bus line 10 of the liquid crystal display panel 31 are connected in parallel. The other end of the sampling capacitor 8 is connected to the common electrode 9. The thin film transistor 7 and the sampling capacitor 8 form a sample hold circuit.

【0004】

On the other hand, the liquid crystal display panel 31 includes the above-mentioned display bus line 10 and a display bus line 11 on the scanning side, which is wired so as to intersect the display bus line 10. A picture element electrode 14 is provided in the area surrounded by the display bus lines 10 and 11, and a thin film transistor 12 which is an analog switch is provided between the display bus lines 10 and 11 and the picture element electrode 14. , A storage capacity 13 is provided between the thin film transistor 12 and the common electrode 9.

【0005】

[Problems to be Solved by the Invention]

By the way, in the conventional liquid crystal display device, since the input bus lines 3, 4 and 5 are formed so as to be close to each other, the parasitic capacitance is formed between the input bus lines 3 and 4, 4 and 5, respectively. 16 and 16 occur. Further, a parasitic capacitance 19 is generated between the shift register output bus line 2 and the analog switch input bus line 6. Further, parasitic capacitances 21 and 22 are generated between the picture element electrodes 14 and the display bus line 10 which are close to each other, and between the same picture element electrodes 14 and the display bus line 11 on the scanning side, respectively.

【0006】

In addition, the wiring part where the shift register output bus line 2 and the input bus lines 3, 4, and 5 intersect, the wiring part where the input bus line 5 and the analog switch input bus line 6 intersect, and the display bus. In the wiring portion where the line 10 and the display bus line 11 on the scanning side intersect, a multilayer wiring is usually provided by providing an interlayer insulating film, but when the thickness of the interlayer insulating film is thin, the interlayer insulating film is usually provided. The above-mentioned intersecting wiring portions also have a non-negligible parasitic capacitance. Specifically, parasitic capacitances 17, 17, and 17 occur between the shift register output bus line 2 and the input bus lines 3, 4, and 5, respectively, and the input bus line 5 and the analog switch input bus line 6 A parasitic capacitance 18 is generated between the stray capacitances 18, and a parasitic capacitance 20 is further generated between the display bus line 10 and the display bus line 11 on the scanning side.

【0007】

Therefore, in the conventional liquid crystal display device, although the above-mentioned parasitic capacitance is generated, signals having different phases and amplitudes are input to the input bus line and the display bus line, thereby analog. There is a problem that crosstalk occurs in the data signal and the image quality on the liquid crystal display panel deteriorates.

【0008】

The present invention has been made to solve the problems of the prior art, and provides a liquid crystal display device capable of preventing the occurrence of parasitic capacitance, causing the occurrence of crosstalk and suppressing the deterioration of image quality of the liquid crystal display panel. The purpose is to do.

【0009】

[Means for solving problems]

The liquid crystal display device of the present invention includes an active matrix type liquid crystal display panel in which picture element electrodes are arranged in a matrix and a display bus line is formed in a display area including the picture element electrodes, and analog data. In a liquid crystal display device including a data driver having an input bus line for inputting a signal to the liquid crystal display panel, a part or all of the input bus line of the data driver and the display bus line of the liquid crystal display panel. On the other hand, a grounded shielded wiring is attached, thereby achieving the above object.

【0010】

The shield wiring is attached to the display bus line and the picture element electrode, has an interlayer insulating film sandwiched between the display bus line and the picture element electrode, and overlaps with each other at 1 μm or more and 10 μm or less. It may be formed as follows.

【0011】

Further, the thin film transistor group which is connected to the display bus line and the element electrode to provide a thin film transistor and constitutes a data driver for inputting analog data to the liquid crystal display panel, and the input bus line and the thin film transistor. Another thin film transistor may be provided by connecting to the display bus line, and each of the thin film transistor group constituting the thin film transistor and the data driver and the other thin film transistor may be formed by using polycrystalline Si.

【0012】

[Action]

In the present invention, a grounded shield wiring is attached to a part or all of the input bus line of the data driver and the display bus line of the liquid crystal display panel. Therefore, it is possible to eliminate the influence of parasitic capacitance and prevent the occurrence of crosstalk of analog data signals.

【0013】

Further, when the shield wiring was formed so that an interlayer insulating film was sandwiched between the display bus line and the picture element electrode and overlapped with each other at 1 μm or more and 10 μm or less, it was caused by distortion of the electric field distribution around the picture element electrode. Light leakage is prevented.

【0014】

Furthermore, when a data driver for inputting analog data to the liquid crystal display panel is integrally formed on the same substrate using polycrystalline Si, the control signal for operating the data driver, the output signal of the data driver, etc. Crosstalk occurs due to the influence, but by forming a shield wiring between the data driver and the analog data signal line, it is possible to eliminate the influence of parasitic capacitance and prevent the occurrence of crosstalk. Become.

【0015】

[Example]

Hereinafter, examples of the present invention will be specifically described.

【0016】

FIG. 1 is an equivalent circuit diagram showing a liquid crystal display device of this embodiment. This liquid crystal display device includes a liquid crystal display panel 31 and a data driver 30 formed on the same substrate. The data driver 30 includes a shift register circuit 1 and a plurality of data drivers 30 having one end connected to the shift register circuit 1. It includes a shift register output bus line 2 and a thin film 7 which is an analog switch connected to the other end of each shift register output bus line 2.

【0017】

Each thin film transistor 7 has a gate electrode formed on one side of a semiconductor layer made of polycrystalline Si, and a source electrode and a drain electrode formed on the other side. The shift register output bus line 2 is connected to the gate electrode, and the source electrode is connected to any one of R, G, B video signal input bus lines 3, 4, and 5 via the analog switch input bus line 6. The sampling capacitor 8 and the display bus line 10 of the liquid crystal display panel 31 are connected in parallel to the drain electrode. The thin film transistor 7 is turned on and off between the two terminals of the source electrode and the drain electrode by the control by the output signal from the shift register circuit 1.

【0018】

The other end of the sampling capacitor 8 is connected to the common electrode 9, and the thin film transistor 7 and the sampling capacitor 8 form a sample hold circuit.

【0019】

Shielded wirings 16a and 16b are formed between the input bus lines 3, 4 and 5 as shown in FIG. 2, and shielded wirings 16c and 16b are similarly formed outside the input bus lines 3 and 5. 16d is formed, and an insulating film 17a is formed so as to cover the shield wirings 16a, 16b, 16c, 16d and the input bus lines 3, 4, and 5. Further, as shown in FIG. 3, with respect to the analog switch input bus line 6, the shield wiring 16f is formed by sandwiching the upper and lower layers with the interlayer insulating films 17a and 17b over the entire length. Similarly, with respect to the shift register output bus line 2, the shield wiring 16e is formed so as to be sandwiched between interlayer insulating films (not shown above and below) over the entire length. The ends of the shield wirings 16a, 16b, 16c, 16d, 16f and 16e are grounded. The shield wirings 16f and 16e described above are always provided at the intersections with the input bus lines 3, 4 and 5, but can be omitted in other portions without any problem.

【0020】

On the other hand, the liquid crystal display panel 31 includes the above-mentioned display bus line 10 and a display bus line 11 on the scanning side, which is wired so as to intersect the display bus line 10. A picture element electrode 14 is provided in the area surrounded by the display bus lines 10 and 11, and a thin film transistor 12 which is an analog switch is provided by connecting the display bus lines 10 and 11 and the picture element electrode 14. .. The thin film transistor 12 has a structure in which a gate electrode is formed on one side and a source electrode and a drain electrode are formed on the other side of a semiconductor layer made of polycrystalline Si, and a display bus line 11 is connected to the gate electrode. A display bus line 10 is connected to the source electrode, and a picture element electrode 14 is connected to the drain electrode. A storage capacity 13 is provided between the thin film transistor 12 and the common electrode 9.

【0021】

With respect to the display bus line 10, shield wiring 16 g is formed by being sandwiched between interlayer insulating films (not shown above and below) over the entire length, and element electrodes 14 are formed in a matrix with respect to the display bus line 11 on the scan side. In the arranged display region portion, the shield wiring 16h is formed by being sandwiched between interlayer insulating films (not shown above and below). The ends of these shielded wires 16g and 16h are grounded. The shield wirings 16g and 16h described above are always provided at the portion where the display bus line 10 and the display bus line 11 on the scanning side intersect and the portion passing near the element electrode 14, but other There is no problem even if it is omitted in the part. However, in the portion passing near the picture element electrode 14, these shield wirings 16g and 16h have an interlayer insulating film sandwiched between the display bus lines 10 and 11 and the picture element electrode 14, and are 1 μm or more and 10 μm or less. It is formed so as to overlap with.

【0022】

Therefore, in the liquid crystal display device configured in this way, as described above, the shield wiring grounded with respect to the input bus lines 3, 4, 5, and the shift register output bus line 2 and the analog switch input bus line 6. Since 16a, 16b, 16c, and 16d are provided, even if analog data signals with different phases and amplitudes are input, the input bus lines 3, 4, and 5 and the shift register output bus line 2 and the analog switch are provided. No parasitic capacitance is formed between the input bus line 6 and cross talk does not occur.

【0023】

Further, since the shield wirings 16g and 16h are provided between the display bus lines 10 and 11 and the element electrode 14, no parasitic capacitance is generated in the vicinity of the display bus lines 10 and 11. It is possible to prevent the occurrence of crosstalk. In addition, since the shield wirings 16g and 16h are formed so as to overlap the display bus lines 10 and 11 and the element electrode 14 at a distance of 1 μm or more and 10 μm or less, due to distortion of the electric field distribution around the element electrode 14. The generated light leakage is prevented by the presence of shielded wiring 16g and 16h.

【0024】

Furthermore, when a data driver for inputting analog data to the liquid crystal display panel is integrally formed on the same substrate using polycrystalline Si, the control signal for operating the data driver, the output signal of the data driver, etc. Crosstalk occurs due to the influence, but by forming a shield wiring between the data driver and the analog data signal line, it is possible to eliminate the influence of parasitic capacitance and prevent the occurrence of crosstalk. Become.

【0025】

For the above reasons, in the case of the present invention, the occurrence of crosstalk can be prevented, so that a high-quality display can be obtained.

【0026】

[Effect of the invention]

As described above, in the case of the present invention, since the shield wiring is provided at a place where parasitic capacitance may occur, it is possible to prevent the occurrence of crosstalk between analog data signals, thereby improving the display quality. Can be made into something.

[Simple explanation of drawings]

[Figure 1]

The equivalent circuit diagram which shows the liquid crystal display device of this Example.

[Figure 2]

FIG. 5 is a cross-sectional view showing the vicinity of the input bus line of FIG.

[Fig. 3]

FIG. 5 is a cross-sectional view showing the vicinity of the input bus line (including the analog switch input bus line) of FIG.

[Fig. 4]

An equivalent circuit diagram showing a conventional liquid crystal display device.

[Explanation of symbols]

1 shift register circuit 2 shift register output bus line 3 R video signal input bus line 4G video signal input bus line 5 B video signal input bus line 6 Bass line for analog switch input 7 thin film transistor 8 sampling capacitor 9 Common electrode 10 Display bus line 11 Scan side display bus line 12 thin film transistor 13 Storage capacity 14 Fluorescent electrode 16a shielded wiring 16b shielded wiring 16c shielded wiring 16d shielded wiring 16f shielded wiring 16e shielded wiring