JP2001033756A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a simple matrix type LCD(Liquid Crystal Display) driven rapidly by multi-division drive and responsible to high contrast and a high frame frequency. SOLUTION: In the liquid crystal display device of the simple matrix type, four-division driven first-fourth scanning line groups 22-25 and first, second, third and fourth signal line groups 26a, 26b, 27b, 27a divided to four parts corresponding to respective scanning line groups 22-25 are provided, and input wiring 28 to the second, third signal line groups 26b, 27b excepting the first signal line group 26a and the fourth signal line group 27a closest to the signal side drivers 26, 27 are formed between respective signal lines of the first signal group 26a and the fourth signal line group 27a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple matrix type liquid crystal display device capable of driving a large liquid crystal panel at a high speed and preventing a decrease in contrast due to a high frame frequency accompanying a large screen of the liquid crystal panel.

[0002]

2. Description of the Related Art A liquid crystal panel 1 of a conventional liquid crystal display (Liquid Crystal Display: LCD) for single scan.
2 is shown in FIG. In the figure, reference numeral 1 denotes a first transparent substrate made of glass or the like having a plurality of scanning lines 2a formed on a main surface thereof, and a second transparent substrate made of glass or the like having a plurality of signal lines 3a formed on a main surface thereof. With the scanning line 2a and the signal line 3a
And a liquid crystal panel of a simple matrix type LCD in which liquid crystal layers such as nematic liquid crystal are bonded to each other with the liquid crystal layers facing each other and orthogonal to each other.
Y480) and the signal line 3a (X1 to X640)
(Indium Tin Oxide). Also,
Reference numeral 2 denotes a scanning line driving circuit (hereinafter, referred to as a scanning side driver) which sequentially inputs a predetermined scanning line driving signal (scanning pulse) to the scanning line 2a (from the upper side in the figure). Signal line drive signal (signal line pulse)
(Hereinafter referred to as a signal side driver).

In FIG. 1, an FRM signal is a frame signal that defines the start timing of one drawing period and the start timing of scanning of the first scanning line 2a. Do. The LOAD signal is a control signal obtained by dividing the FRM signal by the number of scanning lines 2a or more, and is supplied to both the scanning driver 2 and the signal driver 3. Then, in the scanning driver 2, the LOAD signal functions as a scanning clock that defines the input timing of the scanning pulse at its falling edge,
It serves as a shift clock for sequentially shifting the input of the scanning pulse to the next scanning line 2a. On the other hand, in the signal side driver 3, the LOAD signal functions as a clock for outputting the display data taken into the shift register in the signal side driver 3 to the signal line 3a. The CP signal is a dot clock signal, and defines the timing at which display data is captured at the falling edge and stored in a shift register in the signal-side driver 3. D7 to D0 are display data composed of 8 bits per set.

LCD for single scan as shown in FIG.
Then, since the scanning lines 2a are driven line-sequentially, as the number increases, if the scanning pulse width remains unchanged, the frame frequency decreases and flicker (screen flickering) easily occurs. The pulse width is reduced, and the duty of the scanning pulse is reduced. As a result, the liquid crystal molecules are not sufficiently driven and the contrast is reduced.
As a solution to such a problem, as shown in FIG. 3, the screen is divided into upper and lower parts by dividing the signal line into upper and lower parts at the center, and the scanning driver 12 for the upper screen and the scanning for the lower screen are divided. Side driver 14, upper screen signal side driver 13,
Signal side driver 15 for lower screen, scanning line 12 for upper screen
a, upper screen signal line 13a, lower screen scanning line 14
a, a two-split drive method (dual scan drive method) in which a signal line 15a for a lower screen is provided and two upper and lower screens are simultaneously driven.

In this dual scan driving method, it is not necessary to reduce the scanning pulse width. If the number of scanning lines is the same, the duty can be doubled and the contrast can be improved to about twice as compared with the single scan driving method. Even if the number increases, the duty can be maintained or increased, so that the liquid crystal molecules can be sufficiently driven and the contrast can be improved.

In recent years, there has been an increasing demand for larger screens and higher definition of liquid crystal panels, and further increase in the number of scanning lines is expected. In this case, a reduction in contrast and a reduction in response speed are inevitable. Therefore, there is a limit in the dual scan driving method.

In order to solve such a problem, there is provided a first transparent substrate in which a large number of transparent conductive films and transparent insulating layers are laminated to form a multilayer, and a counter electrode provided on the first transparent substrate via a liquid crystal. An LCD which has a second transparent substrate and takes out a plurality of electrodes of liquid crystal pixels in an arbitrary portion of the first transparent substrate from the same outlet to divide a signal line into four parts and perform high-speed driving has been proposed. (Conventional Example 1: JP-A-6-13
No. 8476).

[0008]

However, in the LCD of the prior art 1 described above, for example, two signal electrodes are taken out from the same outlet, and the signal electrode (a electrode) for the upper screen is taken out.
A signal electrode (b-electrode) for the lower screen is formed under the lower screen, and the b-electrode is extended to the lower screen (see FIGS. 1 and 2 of Conventional Example 1). It is multilayered. Further, since the light transmittance is different between the a electrode portion and the b electrode portion, a dummy transparent conductive film is formed below the b electrode to adjust this. Therefore, in the configuration of Conventional Example 1, there is a problem that the light transmittance is extremely reduced as the number of screen divisions is increased, and the manufacturing process is complicated due to the multilayer structure.

Accordingly, the present invention has been completed in view of the above circumstances, and has as its object to drive a screen into two or more divisions while maintaining a high luminance and a high contrast with little decrease in light transmittance. Therefore, a large-sized, high-definition liquid crystal panel can be driven at high speed, and the manufacturing process is not complicated, so that it can be manufactured efficiently at low cost.

[0010]

A liquid crystal display device according to the present invention comprises: a first transparent substrate having a plurality of scanning lines formed on a main surface thereof;
In a simple matrix type liquid crystal display device in which a plurality of signal lines are formed on a main surface and a second transparent substrate is joined via a liquid crystal layer in a state where scanning lines and signal lines are opposed and orthogonal to each other, Signal lines other than the first signal line group closest to the signal line driving circuit, having a plurality of divided scanning line groups and a plurality of divided signal line groups corresponding to the respective scanning line groups. The input wiring to the group is formed between each signal line of the first signal line group.

According to the present invention, it is not necessary to adopt a multi-layer structure in which input wirings are stacked on signal lines, so that light transmittance does not decrease even when multi-segment driving is performed, and good contrast and the like can be maintained. It has the function and effect.

In the present invention, preferably, the sheet resistance of the input wiring is 10 Ω / □ or less. This allows
No difference occurs in the voltage level of the signal line pulse input to each signal line group, and display unevenness due to the luminance difference does not substantially occur.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The LCD of the present invention will be described below. FIG. 1 shows a basic configuration of a liquid crystal panel for four-division simultaneous driving according to the present invention. In the figure, 21 is a liquid crystal panel,
22 is a first scanning line group (Y1 to Y120) at the top of the screen
A first scanning side driver that scans 22a, 23 is a second scanning line group (Y121 to Y240) 23a at the upper center of the screen
, A third scanning side driver for scanning a third scanning line group (Y241 to Y360) 24a at the lower center of the screen, and a fourth scanning line 25 at the bottom of the screen. The fourth scanning side driver scans the group (Y361 to Y480) 25a. 26 is a first scanning line group 22a
The first signal line group (XU1, XU3, XU5,
... XU1279) 26a and 2nd scanning-line group 23a
Signal line group (XU2, XU4, XU6,
.. XU1280) 26b and a signal driver for the upper screen, and 27 is a fourth signal line group (XL1, XL3, XL5,... XL) corresponding to the fourth scanning line group 25a.
1279) 27a and a third signal line group (XL2, XL4, XL6,... XL) corresponding to the third scanning line group 24a.
1280) 27b is a signal side driver for the lower screen.

The four-division simultaneous driving is performed as follows. Regarding the first signal line group 26a and the second signal line group 26b on the upper side of the screen, the signal side driver 26 supplies UD7 of display data to the XU1 electrode and UD to the XU2 electrode.
6, UD5 is output to the XU3 electrode, UD1 is output to the XU1279 electrode, and UD0 is output to the XU1280 electrode. Regarding the fourth signal line group 27a and the third signal line group 27b on the lower side of the screen, XL1
LD7 of display data for electrode, LD for electrode XL2
6, LD5 for the XL3 electrode, LD1 for the XL1279 electrode, and LD0 for the XL1280 electrode. By performing the four-division simultaneous driving as described above, high-speed driving can be performed, and a high frame frequency can be handled. In addition, even with simple calculation, the duty of the scanning pulse can be set to four times (1/120) of the single scan (1/480) and twice of the duty of the dual scan (1/240).
As a result, the contrast is improved.

In this embodiment, four-division simultaneous driving has been described. However, similarly, 2n-division simultaneous driving (n is an integer of 1 or more) may be used, and driving may be performed in multiple divisions. In FIG. 1, the third scanning line group 24a, the third signal line group 27b, and the like can be omitted to perform three-division simultaneous driving. Similarly, the present invention is applied to (2n + 1) -division simultaneous driving. You may. The FRM signal, LOAD signal, C
The P signal, the UD7 to UD0 signals, and the LD7 to LD0 signals are basically the same as those in FIG. 2, but one of the first to fourth scanning line groups 22a to 25a is selected by the LOAD signal. And first to fourth signal line groups 26a, 26
Display data is input to b, 27b, and 27a.

In the present invention, the sheet resistance (surface resistivity) of the signal line is generally 30 Ω / □ or less. Such a signal line is made of a transparent conductive material such as ITO. Also,
The line width of the signal line is different between color and monochrome.
1, VGA (vide
o graphycs array; 640 signal lines x 480 scanning lines
Color) (640 x 3 signal lines)
= 1920 lines) and the screen size is 7.7 inches, about 72
μm or less, about 100 μm or less for color display with a screen size of 10.4 inches, monochrome display (640 signal lines)
In this case, it is preferable that the screen size is about 240 μm or less when the screen size is 7.7 inches, and that the screen size is about 340 μm or less when the screen size is 10.4 inches in monochrome display.

Further, the thickness of the signal line is 0.1 to 0.5 μm.
When m is less than 0.1 μm, the sheet resistance increases, and when it exceeds 0.5 μm, the thickness of the signal line becomes non-uniform and the deposition time becomes longer.

In the present invention, in the case of FIG. 1, four signal line groups 26a, 26b, 27b, and 27a corresponding to the respective scanning line groups 22a, 23a, 24a, and 25a are provided. , 27, the input wiring 28 to a signal line group other than the first signal line group 26a and the fourth signal line group 27a is connected to each of the first signal line group 26a and the fourth signal line group 27a. It is formed between signal lines. This eliminates the necessity of adopting a multilayer structure in which the input wiring 28 is stacked on the signal line as in the related art, so that even if multi-division driving is performed, a decrease in light transmittance can be suppressed and the light transmittance can be maintained. Reference numeral 29 denotes a black matrix which covers the input wiring 28 with a line width equal to or larger than the line width of the input wiring 28 so as not to affect display. The input wiring 28 is connected to the first signal line group 26a.
The fourth signal line group 27a and the fourth signal line group 27a do not need to be parallel in the same plane, and the formation surface may be slightly different (one layer to several layers). For example, the first signal line group 26a (the fourth The formation surface may be different by the thickness of the signal line group 27a).

Further, the line width of the input wiring 28 is preferably 20 μm or less, and if it exceeds 20 μm, the pixel density decreases and the image becomes coarse. Further, the thickness of the input wiring 28 is preferably 0.1 to 0.5 μm. If the thickness is less than 0.1 μm, the sheet resistance increases.
The thickness of the film becomes non-uniform, and the film forming time becomes longer.
The sheet resistance of the input wiring 28 is preferably 10Ω / □ or less, and if it exceeds 10Ω / □, the sheet resistance of the second signal line group 26b is lower than that of the first signal line group 26a due to the electric resistance of the input wiring 28, for example. , The voltage level of the signal line pulse decreases, the luminance of the second signal line group 26b decreases, and display unevenness easily occurs. As the material of the input wiring 28, ITO, Cu, Al, Ag, Au, Cr
And the like.

In the above embodiment, as shown in FIG. 1, the number of signal line drive circuit blocks is two, ie, the upper screen signal driver 26 and the lower screen signal driver 27. The number of line groups is four. Thus, it is basically preferable to apply the present invention when the number of signal line drive circuit blocks is smaller than the number of signal line groups. That is, if the number of signal line groups is larger than the number of signal line drive circuit blocks,
This is because a plurality of signal line groups are input from one signal line drive circuit block. When the number of signal line drive circuit blocks and the number of signal line groups are the same, the configuration of the present invention may be applied.

The LCD of the present invention comprises a first transparent substrate made of glass or the like having a plurality of scanning lines formed on a main surface thereof, and a second transparent substrate made of glass or the like having a plurality of signal lines formed on a main surface thereof. Are connected through a liquid crystal layer such as a nematic liquid crystal in a state where scanning lines and signal lines are opposed to and orthogonal to each other, and a STN (SuperTwi
sted Nematic) LCD, TN (Twisted Nematic)
LCD, ferroelectric liquid crystal LCD, antiferroelectric liquid crystal L
Simple matrix type L such as CD and phase change liquid crystal type LCD
If it is a CD, it can be applied.

Thus, according to the present invention, it is not necessary to adopt a multilayer structure in which the input wiring is laminated on the signal line as in the prior art.
This has the effect that contrast and the like can be maintained well.

It should be noted that the present invention is not limited to the above embodiment, and various changes may be made without departing from the scope of the present invention.

[0024]

Embodiments of the present invention will be described below.

EXAMPLE An LCD having the liquid crystal panel 21 of FIG. 1 was constructed as follows. VGA ｛Number of signal lines 64
0 × 3 (RGB) lines × 480 scanning lines} type, color display, screen size 7.7 inches, sheet resistance of signal lines 30Ω / □, signal line width 62 μm, signal line thickness 0 .15 μm, the sheet resistance of the input wiring 28 is 30Ω /
□, when the width of the input wiring 28 is 15 μm, the thickness of the input wiring 28 is 0.15 μm, the frame frequency is 100 Hz, and the duty of the scanning pulse is 120, the pixel density is 6
9.5%, the difference between the light transmittance in white display and the light transmittance in black display was about 4.9%, and the contrast was about 60, showing excellent characteristics.

On the other hand, as a comparative example, a dual scan type as shown in FIG. 3, which was manufactured in the same manner as in this embodiment except that the duty of the scanning pulse was set to 1/240, was also used. The difference between the light transmittance and the light transmittance for black display was about 3.8%, and the contrast was about 20.

[0027]

According to the present invention, there are provided a plurality of scanning line groups which are divided and driven, and a plurality of signal line groups which are divided corresponding to the respective scanning line groups. By forming the input wiring to the signal line group other than the one signal line group between the signal lines of the first signal line group, it is possible to prevent a decrease in light transmittance even when performing multi-segment driving, and to improve contrast and the like. Has the function and effect of being able to favorably maintain the characteristics described above. In addition, a large-screen liquid crystal panel with an increased number of scanning lines can be driven at high speed by multi-segment driving, and has an excellent effect that it can support a high contrast and a high frame frequency.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a basic configuration of a liquid crystal panel for four-division driving according to the present invention.

FIG. 2 is a block diagram showing a basic configuration of a conventional liquid crystal panel for single scan driving.

FIG. 3 is a block diagram illustrating a basic configuration of a conventional liquid crystal panel for dual scan driving.

[Explanation of symbols]

 1: liquid crystal panel 2: scanning side driver 2a: scanning line 3: signal side driver 3a: signal line 21: liquid crystal panel 22 to 25: first to fourth scanning side driver 22a to 25a: first to fourth scanning Line group 26: upper screen signal side driver 26a, 26b: first and second signal line group 27: lower screen signal side driver 27a, 27b: fourth and third signal line group 28: input wiring 29: Black matrix

Continued on the front page F term (reference) 2H092 GA06 GA33 HA04 NA01 NA05 NA27 PA09 QA07 QA10 QA11 QA13 QA14 2H093 NA07 NA22 ND04 ND08 ND10 ND32 ND54 NE03 NE06 NF05 NF13 NF14 NF17 NF20 NH01

Claims (2)

[Claims] A first transparent substrate having a plurality of scanning lines formed on a main surface thereof and a second transparent substrate having a plurality of signal lines formed on a main surface thereof, wherein the scanning lines and the signal lines are opposed to each other; In a simple matrix type liquid crystal display device joined through a liquid crystal layer in an orthogonal state, a plurality of scanning line groups divided and driven,
A signal line group divided into a plurality corresponding to each scanning line group, and an input wiring to a signal line group other than the first signal line group closest to the signal line driving circuit is connected to a first signal line A liquid crystal display device formed between signal lines of a group. 2. The liquid crystal display device according to claim 1, wherein a sheet resistance of said input wiring is 10 Ω / □ or less.