JPH0573000A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the large-sized liquid crystal display device of good picture quality as to an active matrix type liquid crystal display device which uses thin film transistors(TFT). CONSTITUTION:The liquid crystal display device has a data driver 3, plural data bus lines 5 connected to the data driver 3, a scanning driver 4, plural scanning bus lines 6 connected to the scanning driver 4, the thin film transistors(TFT) 7 provided at the intersections of the data bus lines 5 and scanning bus lines 6, and plural liquid crystal picture elements 8 which are controlled by the respective TFTs 7 and arranged in matrix. One end of a resistance R5 is connected to the output terminal of each data bus line 5 and an optional voltage is impressed to the other terminal of the resistance R5 to drive the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to an active matrix type liquid crystal display device using thin film transistors. In recent years, an active matrix type liquid crystal display device (TF) using a thin film transistor is used.
T-LCD) has been commercialized as a flat display with excellent image quality, and in the future, it is desired to provide a large-sized color liquid crystal display device having an image quality comparable to that of a CRT and a large display capacity.

[0002]

2. Description of the Related Art A liquid crystal display device controls the inclination of liquid crystal molecules (pixel liquid crystal) corresponding to each pixel in accordance with an applied voltage, changes the direction of the optical axis, and combines this with a polarizing plate to display light. Is configured to control the transmission amount of FIG. 5 is a diagram showing an example of optical characteristics of a conventional liquid crystal display device, and FIG. 6 is a diagram for explaining problems in the conventional liquid crystal display device.

FIG. 5 (a) shows the relationship between the liquid crystal applied voltage and the transmissivity when the polarizing plates are arranged in a cross arrangement. In this case, in order to perform full color display, a driving voltage given from the outside according to the display data, For example, control is performed between 2V and 5V.
At present, liquid crystal display devices are being widely used as flat displays, but they have the drawback of having a narrow field of view when compared with CRTs.

FIG. 5B shows the relationship between the applied voltage and the transmittance of the liquid crystal when the liquid crystal display panel is tilted as shown in FIG. 6A. By contrasting FIG. 5 (b) and FIG. 6 (a), θ = 90 ° is directly above the liquid crystal display panel 1 (front).
It corresponds to the case of seeing from the eye 2 and θ = 270 ° is the panel 1
When viewed from directly below (back side), and φ = 30
“°” corresponds to the case where the panel 1 is viewed at an angle of 30 ° from the vertical axis. Here, when the drive voltage is controlled between 2V and 5V, and when the panel is viewed from these angles, the image originally supposed to be displayed in black looks like it appears to float up in white, and gradation display should be performed. A phenomenon that an image is crushed in black occurs, and the image quality of a liquid crystal display panel is significantly deteriorated.

[0005]

FIG. 6 (b) shows a case where the liquid crystal display panel 1 is arranged in the vertical direction and seen by the eyes 21 and 22. Here, the angle φ is the upper end of the panel 1.
The panel 1 from a position (21) which is parallel to 11 by a distance h.
Angle when looking at the lower end 12 of the, or the lower end of the panel 1
The panel 1 from a position (22) that is parallel to 12 and is separated by a distance h.
The angle when the upper end 11 of the is viewed is shown.

As shown in FIG. 6 (c), for example, when the size of the liquid crystal display panel 1 becomes large such as 10 inches or more, even if the panel 1 is not tilted, the panel edge portion is inverted or black. Crushing occurs and the image quality deteriorates. That is, as shown in FIGS. 6 (b) and 6 (c), when the size of the liquid crystal display panel 1 is increased, when the eyes are aligned from the clear viewing distance of the distance h from the panel 1 to the upper end or the lower end,
This is because a viewing angle of angle φ is formed between the opposite end and the same situation as when the panel 1 is tilted and viewed. And
This angle φ increases as the size of the liquid crystal display panel 1 increases, and reversal and blackout at the edges of the panel become a problem.

Specifically, FIG. 6 (c) shows the relationship between the distance L between the upper and lower ends of the panel 1 and the angle φ, in which the distance h between the panel surface and the human eye is h = 30 cm and h = 40 cm. Since the angle where the reversal occurs is 20 ° to 25 °, a problem occurs in a liquid crystal display panel (liquid crystal display device) having a size of 10 inches or more with a screen aspect ratio of 3: 4. It will be.

In view of the problems of the above-mentioned conventional liquid crystal display device, it is an object of the present invention to provide a large-sized liquid crystal display device with good image quality.

[0009]

According to the present invention, a data driver 3; 31, 32, a plurality of data bus lines 5; 51, 52 connected to the data driver 3; 31, 32, and a scan driver. 4, a plurality of scan bus lines 6 connected to the scan driver 4, a plurality of thin film transistors 7 respectively provided at intersections of the data bus lines 5; 51, 52 and the scan bus line 6, A liquid crystal display device having a plurality of liquid crystal pixels 8 controlled by a thin film transistor 7 and arranged in a matrix, wherein resistors R ₅ ; R ₅₁ , R ₅₂ are provided at output terminals of the respective data bus lines 5; 51,52. There is provided a liquid crystal display device characterized in that one end of each of the resistors is connected and the other ends of the resistors R ₅ ; R ₅₁ and R ₅₂ are driven by applying an arbitrary voltage.

[0010]

According to the liquid crystal display device of the present invention, one end of each of the resistors R ₅ ; R ₅₁ , R ₅₂ is connected to the output terminal of each data bus line 5; 51,52, and these resistors R ₅ ; R ₅₁ , ₅₂ are connected. An arbitrary voltage is applied to the other end of R ₅₂ . Where the resistance
To the other ends of R ₅ ; R ₅₁ and R ₅₂ , a voltage that is inverted at a voltage level larger than the central voltage of the data voltage or the maximum amplitude of the data voltage is applied. Then, the data driver 3; 31, 32
The output voltage range is corrected to be wider or narrower depending on the voltage applied to the resistors R ₅ ; R ₅₁ and R ₅₂ . Then, the data voltage is divided by the resistors R ₅ ; R ₅₁ , R ₅₂ provided on the data bus lines 5; 51, 52, and a voltage change similar to the voltage waveforms shown in FIGS. 2 (a) to 2 (c) is generated. This will occur in the vertical direction, and the range of voltage applied to each liquid crystal cell will change in each cell (described in detail in Examples below).

As a result, as shown in FIG. 5 (b) described above, the range in which the brightness changes varies depending on the vertical viewing angle of the liquid crystal display panel, but the range in which the brightness changes is sufficient. It is possible to secure the voltage range in which the luminance change is obtained according to the viewing angle. As described above, according to the liquid crystal display device of the present invention, it is possible to obtain a good image quality even in a large-sized liquid crystal display panel without causing inversion or blackout at the edges.

[0012]

Embodiments of the liquid crystal display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a liquid crystal display device according to the present invention. In the figure, reference numeral 1 is a liquid crystal display panel, 3 is a data driver, 5 is a data bus line, 4 is a scan driver, 6 is a scan bus line, 7 is a thin film transistor, and 8 is a liquid crystal pixel.

The data driver 3 is provided on one side (upper side) of the liquid crystal display panel 1 and applies a data voltage to the source of each thin film transistor 7 via a plurality of data bus lines 5. The scan driver 4 selectively scans liquid crystal pixels 8 in which data is sequentially written via a scan bus line 6 connected to the gates of the thin film transistors 7.
The data from the data driver 3 is written to the thin film transistors 7 in one row connected to one scan bus line 6 selected by the scan driver 4.

Here, in the liquid crystal display device of this embodiment, a resistor R ₅ is provided at the output end of each data bus line _5.
The one end is connected, to the other end of the resistor R ₅ is adapted to any voltage via the terminal 5a is applied. Specifically,
The resistance R ₅ provided at the output end of the data bus line 5 has a value of, for example, about 1 kΩ and a value that does not become larger than the overall resistance value (3 kΩ to ₅ kΩ) of each data bus line 5.

FIG. 2 is a diagram showing output waveforms of the data driver in the liquid crystal display device of the present invention. First, Fig. 2 (a)
When the correction is performed so that the maximum amplitude of the output of the data driver 3 becomes about ± 15 V so as to have the waveform shown in, the resistance value of one data bus line 5 is 3 kΩ to 5 kΩ, for example.
Since it is kΩ, the voltage is divided together with the resistance value (1 KΩ) of the resistor R ₅ provided at the output end of the data bus line 5, and a voltage in the range of 10 V to 13 V from the center voltage is input to the data bus line 5. Will be done. Then, a voltage in the range of 10V to 13V from this center voltage is divided by the resistance of the data bus line of each liquid crystal cell, and a driving voltage (data voltage) in a wide voltage range is applied to the liquid crystal pixel 8 on the input side (upper). Is applied, and a driving voltage in a narrow voltage range is applied to the liquid crystal pixel 8 on the output end side (lower side). That is, the voltage changes similar to the voltage waveforms shown in FIGS. 2A to 2C occur in the vertical direction, and the range of the voltage applied to each liquid crystal cell changes in each cell. As a result, each liquid crystal pixel 8 can be driven in a data voltage range corresponding to the vertical viewing angle of the liquid crystal display panel 1, and a voltage range in which a sufficient luminance change can be obtained can be ensured according to the viewing angle.

Next, in the liquid crystal display device having the structure shown in FIG. 1 described above, a voltage that is inverted at a voltage level larger than the maximum amplitude of the data voltage is applied to the resistor R ₅ provided at the output end of the data bus line 5. Then, correction is performed so that the maximum amplitude of the output of the data driver 3 becomes ± 2V to 3V so that the waveform shown in FIG. As a result, contrary to the case described above, a driving voltage in a narrow voltage range is applied to the liquid crystal pixel 8 on the input side (upper side), and a liquid crystal pixel 8 on the output end side (lower side) has a wider voltage range. A drive voltage will be applied. As a result, each liquid crystal pixel 8 can be driven in a data voltage range corresponding to the vertical viewing angle of the liquid crystal display panel 1, and a voltage range in which a sufficient luminance change can be obtained can be secured according to the viewing angle.

In the above, in the liquid crystal display device shown in FIG. 1, the voltage applied to the resistor R ₅ provided at the output end of the data bus line 5 is changed for each data bus line, so that the line inversion drive can be supported. You can FIG. 3 is a diagram showing another embodiment of the liquid crystal display device according to the present invention. In the figure, reference numeral 1 is a liquid crystal display panel, 31, 32.
Is a data driver, 51 and 52 are data bus lines, 4 is a scan driver, 6 is a scan bus line, 7 is a thin film transistor, and 8 is a liquid crystal pixel.

The data drivers 31 and 32 are provided on both sides of the liquid crystal display panel 1, and each has a data bus line 51.
A data voltage is applied to the source of each thin-film transistor 7 via 52 and 52. The scan driver 4 includes a scan bus line 6 connected to the gate of each thin film transistor 7.
The liquid crystal pixels 8 into which data is sequentially written are selectively scanned via the data driver 31 and 32 for one row of thin film transistors 7 connected to one scan bus line 6 selected by the scan driver 4. The data of is written.

[0019] Here, in the liquid crystal display device of this embodiment, each end of the resistor R ₅₁ and R ₅₂ to the output end of the data bus lines 51 and 52 are connected, these resistors R ₅₁
And an arbitrary voltage is applied to the other end of R ₅₂ via terminals 51a and 52a. Specifically, the resistors R ₅₁ and R ₅₂ provided at the output ends of the data bus lines ₅₁ and ₅₂ are
For example, with a value of about 1 kΩ, each data bus line 51, 52
Of the total resistance value (3 kΩ to 5 kΩ).

In the embodiment shown in FIG. 3, the central voltage of the data voltage is applied to the resistor R ₅₁ provided on one of the data bus lines 51, so that the data has the waveform shown in FIG. 2 (a). Correction is performed so that the maximum amplitude of the output of the data driver 31 to which the bus line 51 is connected is about ± 15V. In addition, the resistor R ₅ provided on the other data bus line 52
₂ is applied with a voltage that inverts at a voltage level of about ± 15 V, which is larger than the maximum amplitude of the normal data voltage as shown in FIG. 4, so that the data bus has the waveform shown in FIG. 2 (c). Correction is performed so that the maximum amplitude of the output of the data driver 32 connected to the line 52 is about 2 to 3V. As a result, the range of the data voltage at the upper end or the lower end of the liquid crystal display panel 1 is widened and the range of the data voltage at the lower end or the upper end is narrowed, and the voltage according to the viewing angle is applied to each liquid crystal cell (pixel liquid crystal). 8) can be applied.

In the above embodiment, by changing the voltage waveforms shown in FIGS. 2 (a) to (c) and FIG. 4 from the outside, the optimum data voltage range can be set in accordance with the position where the liquid crystal display panel is viewed. It can be configured to set.

[0022]

As described above in detail, according to the liquid crystal display device of the present invention, a resistor is provided at the output end of each data bus,
By applying a voltage that is inverted at a voltage level larger than the center voltage of the data voltage or the maximum amplitude of the data voltage to the end of the resistor, a large-sized liquid crystal display device with good image quality can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a diagram showing an output waveform of a data driver in the liquid crystal display device of the present invention.

FIG. 3 is a diagram showing another embodiment of the liquid crystal display device of the present invention.

FIG. 4 is a diagram showing a voltage waveform applied to a resistance at an output end of a data bus in the liquid crystal display device of the present invention.

FIG. 5 is a diagram showing an example of optical characteristics of a conventional liquid crystal display device.

FIG. 6 is a diagram for explaining a problem in a conventional liquid crystal display device.

[Explanation of symbols]

 1 ... Liquid crystal display panel 2, 21, 22 ... Eyes 3, 31, 32 ... Data driver 4 ... Scan driver 5, 51, 52 ... Data bus line 6 ... Scan bus line 7 ... Thin film transistor 8 ... Liquid crystal pixel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masafumi Itozuka 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (8)

[Claims] 1. A data driver (3; 31, 32) and a plurality of data bus lines (5; 51, 5) connected to the data driver.
2), a scan driver (4), a plurality of scan bus lines (6) connected to the scan driver, and a plurality of thin film transistors (7) respectively provided at intersections of the data bus lines and the scan bus lines. ) And a plurality of liquid crystal pixels (8) controlled by the thin film transistors and arranged in a matrix, wherein the output terminals of the data bus lines (5; 51, 52) are respectively provided with resistors. A liquid crystal display device characterized in that one end of (R ₅ ; R ₅₁ , R ₅₂ ) is connected, and an arbitrary voltage is applied to the other end of the resistor for driving. 2. A plurality of data bus lines (5) are connected to a data driver (3) provided on one side of the liquid crystal display panel (1), and resistors provided at the output ends of the respective data bus lines are connected.
2. The liquid crystal display device according to claim 1, wherein (R ₅ ) is provided at a position facing the data driver, and the center voltage of the data voltage is applied to the resistance of each output terminal. 3. A plurality of data bus lines (5) are connected to a data driver (3) provided on one side of the liquid crystal display panel (1), and resistors provided at the output ends of the respective data bus lines.
(R ₅ ) is provided at a position facing the data driver, and a voltage that is inverted at a voltage level larger than the maximum amplitude of the data voltage is applied to the resistance of each output end. Liquid crystal display device. 4. The plurality of data bus lines (51, 52)
Are provided on both sides of the liquid crystal display panel (1).
The data drivers (31, 32) are alternately connected one by one or a plurality of lines, and the resistors (R ₅₁ , R ₅₂ ) provided at the output end of each data bus line are connected to the data bus line. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is provided at a position facing the data driver, and a voltage which is inverted at a voltage level larger than the maximum amplitude of the data voltage is applied to the resistance of each output terminal. 5. A resistor (R ₅₁ ) provided at an output end of a data bus line (51) connected to the first data driver (31)
Is applied to the central voltage of the data voltage, and the resistance (R ₅₂ ) provided at the output end of the data bus line (52) connected to the second data driver (32) is larger than the maximum amplitude of the data voltage. The liquid crystal display device according to claim 4, wherein a voltage inverted at a voltage level is applied. 6. A resistor (R ₅₁ ) provided at an output end of a data bus line (51) connected to the first data driver (31).
Voltage applied to the resistor provided at the output end of the data bus line (52) connected to the second data driver (32).
5. The liquid crystal display device according to claim 4, wherein the voltage applied to (R ₅₂ ) is opposite to that applied. 7. The polarity of the data voltage supplied to each of the data bus lines (5; 51,52) depends on each of the data bus lines (5; 51,52).
52) When a line inversion drive in which each line is inverted is applied, a voltage which is inverted for each line is applied to the resistors (R ₅ ; R ₅₁ , R ₅₂ ) at the output ends. The liquid crystal display device according to claim 1, wherein Resistance of the output end of the; (51, 52 5) wherein said data bus line; the voltage applied to the _{(R 5 R 51, R 5} 2), characterized in that so as to change from the outside The liquid crystal display device according to claim 1.