JPH021822A - Active matrix type liquid crystal display device - Google Patents

Abstract

PURPOSE:To decrease the number of lead-out lines to common bus lines and to prevent a fill factor from decreasing by providing the common bus line to every other area between two scanning bus lines and connecting the common bus lines to the drains of TFT on both sides in common. CONSTITUTION:A liquid crystal display panel consists of two glass substrates 10 and 20 where liquid crystal cells 1 are arranged, scanning bus lines 4, common bus lines 5, and one electrode 11 of a liquid crystal cell 1 are provided on the side of the glass substrate 10, and data bus lines 3 are provided on the side of the glass substrate 20. Here, the common bus lines 5 are provided to alternate areas between the scanning bus lines 4 and two scanning lines 4 to unite the common bus line of liquid crystal cells 1 for two lines. The drain of the TFT2 on both sides are connected to the common bus line 5 in common, so the number of lead-out lines of the common buses 5 is decreased and the fill factor is prevented from decreasing.

Description

[Detailed Description of the Invention] [Summary] Regarding a facing matrix type active matrix type liquid crystal display device, the purpose of this invention is to reduce the number of lines drawn out to the outside of the liquid crystal display panel and prevent a decrease in fill factor. A switching element, one electrode of the display element, scanning bus lines provided in parallel, and a common bus line provided in every other area between the two scanning bus lines are provided on the substrate. , the switching element is provided in a region between the scanning bus line and the common bus line, and its gate is connected to the scanning bus line, its source is connected to the electrode of the display element, and its drain is connected to the common bus line. A data bus line serving as the other electrode of the display element is formed on the other substrate to form an active matrix liquid crystal display device.

[Industrial application field]

The present invention relates to an improvement in a facing matrix active matrix liquid crystal display device.

2. Description of the Related Art In recent years, research and development have been actively conducted on autative matrix drive type flat displays that use liquid crystals as display elements. Since this active matrix drive type flat display can have a smaller depth than a cathode ray tube, it has also been commercialized as a display device for pocket televisions, laptop computers, and the like.

However, in conventional active matrix liquid crystal display devices, data bus lines for writing data to the liquid crystal and scanning bus lines for switching elements that control this writing are arranged in a matrix on a single substrate, intersecting each other. Therefore, the yield of liquid crystal display devices has been reduced due to short circuits at the cross portions between the two. Therefore, a switching element, one electrode of the liquid crystal, a scanning bus line, and a common bus line are provided on one substrate sandwiching the liquid crystal, and a data bus line, which becomes the other electrode of the liquid crystal, is formed on the other substrate. A facing matrix active matrix liquid crystal display device has been proposed (Japanese Patent Laid-Open No. 133478/1983).

However, in this facing matrix active matrix type liquid crystal display device, one scanning bus line and one common bus line are required for each line of liquid crystal, and the number of lines drawn out to the outside of the liquid crystal display panel increases. is desired.

[Conventional technology]

FIG. 7 shows the structure of a portion of a display panel of a conventional facing matrix active matrix liquid crystal display device. As shown in this figure, the conventional active matrix display device is constructed by sandwiching a display layer in which a liquid crystal cell 1 is arranged between two glass substrates 10 and 20. On one glass substrate +H10, thin film transistor 2 (hereinafter referred to as TFT2), which is a switching element, and each TFT2
The scanning bus line 4 connecting the gate I-G of the gate I-G, the external lead-out electrode 14 provided at the end thereof, one electrode 11 of the liquid crystal cell connected to the source S of the TFT 2, and each TFT
A common bus line 5 connecting the drain D of the FT 2 and an external lead-out electrode 15 provided at the end thereof are formed, and data bus lines 3 are arranged in the column direction on the other glass substrate 2o. It is formed as a common electrode.

FIG. 8 shows an equivalent circuit of the active matrix liquid crystal display device of FIG. Scan bus lines 4 and common bus lines 5 are provided alternately in the row direction (horizontal direction) in the display panel of an active matrix liquid crystal display device, whereas data bus lines 3 are provided in the column direction (vertical direction). is provided so as to intersect the scanning bus line 4 and the common bus line 5. and scan bus line 4
, one liquid crystal cell l is located in the area surrounded by the common bus line 5 and two data bus lines 3;
The gate G of the FET 2 is connected to the scanning bus line 4, the source S to one electrode of the liquid crystal cell 1, and the drain D to the common bus line 5. Further, the other electrode of the liquid crystal cell l is connected to the data bus line 3.

The active matrix liquid crystal display device configured as described above is driven as shown in FIG. 9, for example. That is,
Since the liquid crystal cell 1 deteriorates unless an AC voltage is applied,
The common bus line 5 is held at O■ as shown by the waveform A, and the voltage of the data bus line 3 is an alternating voltage centered on the potential of the common bus line 5, as shown by the waveform start.

The period of the alternating voltage on data bus line 3 is one vertical scanning time (16.7m5) of Rusk scan in TV video.
It is twice as much. The scanning bus line 4 is normally maintained at less than OV, as shown by the waveform C, and becomes high voltage only when the TPT 2 is turned on.

Generally, the time for turning on TFT2 is 60 μs.

Then, each time the TPT2 is turned on, the data on the data bus line 3 at that time is written into the liquid crystal cell 1 as shown by waveform 2.

[Problem to be solved by the invention]

However, in the conventional active matrix liquid crystal display device configured as described above, each row of liquid crystal cells 1 has one
Since each scanning bus line 4 and common bus line 5 are required, the number of lines drawn out to the outside of the liquid crystal display panel is twice that of the conventional matrix type. There is a problem that the area ratio) is decreasing.

An object of the present invention is to reduce the number of lines drawn out to the outside of a liquid crystal display panel to prevent a decrease in fill factor.

[Means to solve the problem]

The structure of an active matrix type liquid crystal display device of the present invention that achieves the above object is shown in FIG.

In the active matrix liquid crystal display device of the present invention, on one of the substrates 10 disposed facing each other, the TPT 2 and the scan bus line 4 provided in parallel, and one area between the two scan bus lines 4 are provided. Separate common bus line 5
and one electrode 11 of the liquid crystal cell 1 are provided.

The TFT 2 is provided in a region between the scanning bus line 4 and the common bus line 5, and its gate is connected to the scanning bus line 4, and its source is connected to the electrode 11 of the liquid crystal cell 1. The drain is connected to the common bus line 5. A data bus line 3 serving as the other electrode of the liquid crystal cell 1 is disposed on the other substrate 20.
is formed.

[For production]

According to the active matrix liquid crystal display device of the present invention, a common bus line 5 is provided in every other area between two scanning bus lines 4 on one of the opposing substrates. 5 has TP in the rows on both sides of it.
Since the drains of T2 are commonly connected, the number of external lines of the common bus line 5 is reduced.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 shows the structure of an embodiment of an active matrix liquid crystal display device according to the present invention, and the same members as those in the prior art are given the same reference numerals.

In FIG. 2, 100 is a liquid crystal display panel, and this liquid crystal display panel 100 is constructed by sandwiching a display layer on which a liquid crystal cell 1 is arranged between two glass substrates 10 and 20, as in the conventional case. A TPT (thin film transistor) 2, a scanning bus line 4, a common bus line 5, and one electrode 11 of the liquid crystal cell 1 are provided, and a glass substrate Fi20 is provided.
A data bus line 3 is provided on the side, and the configuration will be shown here using an equivalent circuit thereof.

The liquid crystal display panel 100 includes scanning bus lines 4 provided in parallel, common bus lines 5 provided in every other area between the two scanning bus lines 4, and data bus lines intersecting these. 3 are provided. The TPT 2 is provided in a region between the scanning bus line 4 and the common bus line 5, and its gate is connected to the scanning bus line 4, its source is connected to the electrode of the liquid crystal cell 1, and its drain is connected to the common bus line 4. 5.

A data bus line drive circuit 30, a scan bus line drive circuit 40, and a common bus line drive circuit 50 are provided outside the liquid crystal display panel 100. The data bus line drive circuit 30 is connected to each data bus line 3 in the liquid crystal display panel 100, and can drive each data bus line 3 independently. The scanning bus line driving circuit 40 is connected to each scanning bus line 4 in the liquid crystal display panel 100, and can drive each scanning bus line 4 independently. On the other hand, the common bus line 5 in this embodiment is connected to the common bus line drive circuit 50 after concentrating outside the liquid crystal display panel 100. Therefore, the potentials of the common bus lines 5 in this embodiment all change in the same way.

FIG. 3 shows an example of the arrangement of each member on one glass substrate 10 of the liquid crystal display panel 100. For the sake of explanation, in this example, the liquid crystal display panel 100 has four liquid crystal cells 1 per row. are arranged in four rows.

In the figure, 41.42.43.44 indicate scanning bus lines, and these scanning bus lines 41.42, 4
3° 44 are the electrodes G1 . G2. G3. Connected to G4.

Further, 1. Common bus lines 51.52 are provided between the scanning bus lines 41.42 and 43.44, and these common bus lines 51.52 are also connected to each other at the ends of the liquid crystal display panel 100. Connected to electrodes CI and C2. and between the scan bus line 41 and the common bus line 51, between the scan bus line 42 and the common bus line 51, between the scan bus line 43 and the common bus line 52, and between the scan bus line 44 and the common bus line 52.
Four TPTs 2 and four display electrodes 11 are provided between the two. The gates 1-G of the TPT2 are connected to the scanning bus lines 41, 42, 43.44 for each row, the source S is connected to the electrode 11 of the liquid crystal cell provided in each row, and the drain D is connected to the electrode 11 of the liquid crystal cell provided in each row. It is connected to a common bus line 51, 52, which is provided one at a time.

Next, an example of driving the active matrix liquid crystal display device of the present invention configured as shown in FIG. 2 will be explained with reference to FIG. 4.

In this embodiment, the common bus line 5 is condensed and connected to a common bus line drive circuit 50, and the waveform (
It is held at OV as shown in a).

Therefore, the drive waveform of this embodiment is almost the same as the drive waveform of the conventional device shown in FIG. That is, the voltage of the data bus line 3 is a waveform (as shown by bl, an alternating voltage of ±4■ with two periods of 16.7 ms centered around 0■), and the scan bus line 4 is normally a voltage of ±4■, as shown by the waveform (C). The voltage is less than 0.0V (for example, -10V), and the voltage may be set high (for example, +10V) only during 60 μs during which data on the data bus line 3 is written into the liquid crystal cell 1.

In this way, in the device shown in FIG. 2, the number of common bus lines 5 drawn out to the outside of the liquid crystal display panel 100 can be reduced. In the device of this embodiment, the off-bias of the TFT 2 (potential V, FF from the normal potential of the scanning bus line 4 to the common bus line 5) can be freely set by setting the voltage applied to the common bus line 5. .

FIG. 5 shows the configuration of another embodiment of the driving device for an active matrix type liquid crystal display device according to the present invention. The connection of the bus line to the drive circuit 40 is exactly the same as in the embodiment shown in FIG. The device shown in FIG. 5 differs from the device shown in FIG. 2 in the connection of the common bus line 5 of the liquid crystal display panel 100 to the drive circuit 50 of the common bus line. In the device shown in FIG. 2, the common bus lines 5 are condensed and connected to the common bus line drive circuit 50, but in this embodiment, the common bus lines 5 are each independently connected to the common bus line drive circuit 50. The common bus line 5 can be separately driven by a common bus line drive circuit 50. That is, the embodiment shown in FIG. 5 is an example in which the electrodes CI and C2 in FIG. 3 are each independently connected to the drive circuit 50 of the common bus line.

FIG. 6 shows drive waveforms for the device shown in FIG. In this embodiment, the voltage of the data bus line 3 is ±IV as shown by the waveform VD, and its period is the same as that of the conventional device. In this embodiment, since the common bus line 5 is taken out independently, the common bus line drive circuit 50 performs line sequential driving. To explain this using FIG. 3, a voltage (10V) shown by the waveform VGI is applied to the electrode G1 of the scanning bus line in the first row of the liquid crystal cell 1 from time t1 to t2, and A voltage (IOV) shown by a waveform Vli2 is applied to the line electrode G2 from time t2 to t3. The common bus line 5 of the liquid crystal cells 1 in the first and second rows is supplied with a voltage (-3V) shown by an open square from time tl to t3 to the electrode C1.
is applied to As a result, a data voltage V, -Vc=±4 (v) necessary for writing is applied to the liquid crystal cell 1.

From the subsequent time t3 to t5, the same voltage is applied to the liquid crystal cells 1 in the third and fourth rows in waveform VG3 and waveform VG.
The voltage is applied as shown at 4. The above is data bus line 3
This is the waveform for the positive frame period when the voltage of the data bus line 3 is a positive voltage, but during the negative frame period when the voltage of the data bus line 3 is negative, the voltage value of the common bus line 5 is positive as shown in FIG. voltage (+3V).

When the liquid crystal display panel 100 is driven by lowering the voltage of the data bus line 3 in this manner, crosstalk caused by parasitic capacitance is reduced.

〔Effect of the invention〕

As explained above, according to the active matrix liquid crystal display device of the present invention, the number of common bus lines for the two rows of liquid crystal cells of the liquid crystal display panel is reduced to one, so the number of lines drawn out to the outside of the liquid crystal display panel is reduced. This has the effect of preventing a decrease in fill factor.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an active matrix type liquid crystal display device of the present invention, and FIG. 2 is a diagram of the active matrix type liquid crystal display device of the present invention.
3 is a diagram showing the internal configuration of the display panel in FIG. 2, FIG. 4 is a waveform diagram showing an example of driving the device in FIG. 2, FIG. 5 is a diagram showing the configuration of another embodiment of the active matrix type liquid crystal display device of the present invention, FIG. 6 is a waveform diagram showing an example of driving the device of FIG. 5, and FIG. 7 is a diagram showing a conventional active matrix type liquid crystal display device. A perspective view showing the structure of a liquid crystal display device, FIG. 8 is an equivalent circuit diagram of FIG. 7,
FIG. 9 is a driving waveform diagram of the active matrix liquid crystal display device of FIG. 8. DESCRIPTION OF SYMBOLS 1...Liquid crystal cell, 2...Thin film transistor (TPT), 3...Data bus line, 4...Scanning bus line, 5...Common bus line, 11...One electrode of liquid crystal cell , 30... Data bus line drive circuit, 40... Scanning lot line drive circuit, 50... Common bus line drive circuit, 100... Liquid crystal display panel. Fig. 2 shows an example of the structure of a glass substrate. Fig. 2 is a driving waveform diagram of the device shown in Fig. 2. Fig. 4 is a diagram showing the structure of another embodiment of the present invention.

Claims (1)

[Claims] A switching element (two
), one electrode (11) of the display element (1), a scan bus line (4) provided in parallel, and a scan bus line (4) provided in every other area between the two scan bus lines (4). a common bus line (5), wherein the switching element (2) is connected to the scanning bus line (4);
) and the common bus line (5), and its gate is located between the scanning bus line (4) and the common bus line (5).
, the source is connected to the electrode (11) of the display element, the drain is connected to the common bus line, and the data serving as the other electrode of the display element (11) is disposed on the other substrate (20). An active matrix liquid crystal display device with a facing matrix configuration in which a bus line (3) is formed.