JP2002182240A - LCD panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent flicker and image sticking in an active matrix type liquid crystal display panel using a liquid crystal having a low voltage holding ratio such as a GH liquid crystal, a polymer dispersed liquid crystal and a DSM liquid crystal. SOLUTION: GH liquid crystal, polymer dispersed liquid crystal and DS
In a liquid crystal display panel using a liquid crystal having a low voltage holding ratio, such as an M liquid crystal, an auxiliary capacitor having a capacitance value that is five times or more the capacitance of the liquid crystal cell is connected to the liquid crystal cell. For example, in the case of a reflective liquid crystal display panel, a lower electrode 11b and an upper electrode 16d of an auxiliary capacitor having an area of 50% or more of the reflective electrode 18a are arranged below the reflective electrode (pixel electrode) 18a.
In the case of a transmissive liquid crystal display panel, the pixel electrode, the lower electrode 11b, and the upper electrode 16d are all formed of a transparent conductive material such as ITO.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a GH (Guest Hos
t: Guest-host liquid crystal, polymer dispersion (Polymer Dis
persed) liquid crystal or DSM (Dynamic Scattering Mod)
e: dynamic scattering type) relates to a liquid crystal display panel using a liquid crystal having a low voltage holding ratio such as a liquid crystal.

[0002]

2. Description of the Related Art Liquid crystal display panels are advantageous in that they are thin and lightweight, can be driven at a low voltage, and consume little power, and are widely used in various electronic devices. In particular, T
An active matrix type liquid crystal display device in which an active element such as an FT (Thin Film Transistor) is provided for each pixel has a CRT (Cathod) in view of display quality.
e-Ray Tube) and is used as a computer display device.

A TN (Twisted Nematic) mode liquid crystal display device generally used as a display device of a computer has a structure in which liquid crystal is sealed between a pair of transparent substrates. Of two surfaces (opposing surfaces) of the substrates facing each other, a common electrode, a color filter, an alignment film, and the like are formed on one surface side, and a TFT,
A pixel electrode, an alignment film, and the like are formed. A polarizing plate is attached to a surface of the transparent substrate opposite to the opposite surface. On the back side of the liquid crystal display panel, a light source called a backlight is arranged. Hereinafter, the substrate on which the TFTs and the pixel electrodes are formed is called a TFT substrate, and the substrate on which the color filters are formed is called a CF substrate.

[0004] By the way, a liquid crystal display device having a backlight has an advantage that it is hardly affected by surrounding light and darkness and can always obtain a clear image. However, there is a disadvantage that it cannot withstand long-term use. Therefore, portable computers and PDAs (Personal Digital Assista
As a display device for an nt (portable information terminal), a reflective liquid crystal display panel that does not require a backlight has been attracting attention. In addition to a TN mode liquid crystal, a GH liquid crystal, a polymer dispersion type liquid crystal, or a DSM liquid crystal is used for the reflection type liquid crystal display panel because a polarizing plate is unnecessary and a bright display is possible.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed GH
Conventional liquid crystal display panels using liquid crystal, polymer dispersed liquid crystal, DSM liquid crystal or the like are considered to have the following problems. That is, the conventional active matrix type T
In an N-mode liquid crystal display panel, by providing an auxiliary capacitor about twice as large as a liquid crystal cell, a voltage drop during a period from the writing of a data signal to the writing of the next data signal, that is, one frame (16.7 ms) is reduced. are doing. However, the TN mode liquid crystal cell itself has a voltage holding ratio of about 90% in one frame period, whereas the GH liquid crystal, polymer dispersed liquid crystal or DSM liquid crystal cell has a voltage holding ratio of one frame period. Since it is as low as 50% or less, there is a problem that even if an auxiliary capacitance about twice as large as that of the liquid crystal cell is added, the amount of voltage drop in one frame period is large and flicker occurs. There is also a problem that image sticking occurs because the voltage holding ratio differs depending on the liquid crystal cell.

This tendency becomes more pronounced in a high-definition liquid crystal display panel in which the size of the pixel electrode is limited. For example, in a GH liquid crystal cell or a polymer dispersed liquid crystal cell in which the length of one side of a pixel electrode is about 50 μm, the voltage holding ratio of the liquid crystal cell itself in one frame period is 50% or less, and the capacitance value of the auxiliary capacitor is If it is twice as large as the liquid crystal cell, the voltage holding ratio in one frame period is about 83%. With such a voltage holding ratio, occurrence of flicker or burn-in cannot be avoided.

The present invention relates to an active matrix liquid crystal display panel using a liquid crystal having a low voltage holding ratio, such as a GH liquid crystal, a polymer dispersed liquid crystal, and a DSM liquid crystal, and provides a liquid crystal display panel capable of preventing flicker and image sticking. Aim.

[0008]

A liquid crystal display panel according to the present invention is an active matrix type liquid crystal display panel in which liquid crystal cells having a voltage holding ratio of 50% or less per frame (16.7 ms) are arranged in a matrix. The liquid crystal cell has a capacitance value that is five times or more the capacitance of the liquid crystal cell, and has an auxiliary capacitance connected to the liquid crystal cell.

In the present invention, an auxiliary capacitor having a capacitance value that is five times or more the capacitance of the liquid crystal cell is connected to the liquid crystal cell. GH liquid crystal, polymer dispersed liquid crystal or D having a voltage holding ratio of 50% or less for one frame (16.7 ms)
Even in a liquid crystal cell using an SM liquid crystal, the voltage holding ratio in one frame period can be made 90% or more by connecting an auxiliary capacitor having a capacitance value of five times or more the capacitance of the liquid crystal cell. it can. As a result, occurrence of flicker and image sticking can be prevented.

In the case of a transmissive liquid crystal display panel which is generally used at present, when the auxiliary capacitance is increased as described above, the aperture ratio is remarkably reduced, the image becomes dark, and the display quality is deteriorated. However, when a reflective liquid crystal display panel is formed by utilizing the characteristics of a GH liquid crystal, a polymer dispersed liquid crystal, or a DSM liquid crystal, an auxiliary capacitance electrode can be formed over a pixel electrode (reflective electrode). An auxiliary capacitor having a large capacitance value can be formed without lowering the quality. Also, even for a transmissive liquid crystal display panel,
By forming the electrode of the auxiliary capacitor with a transparent conductor such as ITO (indium-tin oxide), a decrease in aperture ratio can be avoided, and good display quality can be obtained.

It should be noted that JP-A-6-235938 and JP-A-7-13516 propose to increase the value of the auxiliary capacitance in order to prevent flicker, display unevenness and image sticking. Further, Japanese Unexamined Patent Publication No. Hei.
In No. 9, the capacitance value of the auxiliary capacitor is set to 5 to 1 of the capacitance of the liquid crystal cell.
It has been proposed to set it to 0 times. However,
Since all of the liquid crystal display devices described in these publications are transmissive, when the electrode size of the auxiliary capacitor is increased, the aperture ratio is reduced and the screen becomes dark. Therefore,
It is not practical to set the capacitance value of the auxiliary capacitor to five times or more the capacitance value of the liquid crystal cell in a liquid crystal cell in which the voltage holding ratio of a single liquid crystal cell generally used in the past is 90% or more.

On the other hand, in the present invention, a liquid crystal such as a GH liquid crystal, a polymer dispersed liquid crystal and a DSM liquid crystal which has a low voltage holding ratio but can form a liquid crystal display panel without using a polarizing plate is used. Therefore, even if the capacitance value of the auxiliary capacitance is set to five times or more the capacitance of the liquid crystal cell,
It is possible to realize a liquid crystal display panel that is bright and has excellent display quality.

Further, another liquid crystal display panel of the present invention comprises:
50% voltage holding ratio in frame (16.7 ms)
An active matrix type liquid crystal display panel in which the following liquid crystal cells are arranged in a matrix, wherein a plurality of gate bus lines to which a scanning signal is supplied, a plurality of data bus lines to which a data signal is supplied, and the gate A storage capacitor and a pixel electrode respectively formed in each pixel region surrounded by a bus line and the data bus line; a gate electrode connected to the gate bus line; a drain electrode connected to the data bus line; A first transistor having an electrode connected to the storage capacitor; a gate electrode connected to a source electrode of the first transistor; a drain electrode connected to a constant voltage source; and a source electrode connected to the pixel electrode. And a second transistor.

In the present invention, while the scan signal is being supplied to the gate electrode of the first transistor, the data signal supplied via the data bus line is stored in the auxiliary capacitance. Then, the voltage of the storage capacitor is supplied to the gate electrode of the second transistor, and a driving voltage is supplied to the liquid crystal cell via the second transistor. Thus, even in a liquid crystal cell having a low voltage holding ratio, a constant voltage is supplied through the second transistor, so that flicker and burn-in can be avoided, and good display quality can be obtained. Further, in the present invention, since the second transistor is connected between the storage capacitor and the liquid crystal cell, leakage of the charge stored in the storage capacitor is extremely small. Therefore, the capacitance value of the auxiliary capacitance can be reduced.

The liquid crystal display panel of the present invention can perform gradation display by performing field sequential driving.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a schematic sectional view of a liquid crystal display panel according to a first embodiment of the present invention, FIG. 2 is a plan view showing a TFT substrate of the liquid crystal display panel, and FIG. It is an equivalent circuit diagram of one pixel of a panel. FIG. 1 is the same as FIG.
2 shows a cross section at a position corresponding to line AA.

The liquid crystal display panel of the present embodiment has a TFT
TF on which a pixel electrode 20 and a pixel electrode (reflection electrode) 18a are formed
T substrate (glass substrate) 10, CF substrate (glass substrate) 3 on which color filter 32 and common electrode 33 are formed
0, and a liquid crystal 40 sealed between them. One pixel electrode 18a and the common electrode 33
A liquid crystal cell 22 shown in the equivalent circuit diagram of FIG. In the display area of the liquid crystal display panel, such liquid crystal cells 22 are arranged in a matrix in the horizontal and vertical directions.

In the liquid crystal display panel of the present embodiment, one field (1) of the liquid crystal cell 22 alone is used as the liquid crystal 40.
A liquid crystal having a voltage holding ratio of 50% or less for a period of 6.7 ms) is used. Specifically, GH liquid crystal, polymer dispersed liquid crystal,
A DSM liquid crystal or another liquid crystal having a specific resistivity of 10 ¹⁰ Ωcm or less is used. The TFT substrate is configured as follows. That is, a plurality of gate bus lines 11 extending in the horizontal direction in parallel with each other are formed on the glass substrate 10.
a and a plurality of data bus lines 16a which intersect these gate bus lines 11a at right angles with an insulating film interposed therebetween. Each rectangular area surrounded by the gate bus line 11a and the data bus line 16a is a pixel area. TFT for each pixel area
20; a reflective electrode (pixel electrode) 18a;
d is formed.

The TFT 20 uses a part of the gate bus line 11a as a gate electrode. On this gate electrode, a silicon film (not shown) is formed via an insulating film. The source electrode 16b and the drain electrode 16c of the TFT 20 are arranged with the gate bus line 11a interposed therebetween, and are electrically connected to both ends of the silicon film. The source electrode 16b has a contact hole 17
The drain electrode 16c is connected to the data bus line 16a, and is connected to the reflective electrode 18a and the storage capacitor 21 via the terminals a and 17b.

As shown in FIG. 2, the reflection electrode 18a is formed as large as possible by using a light-reflecting material such as aluminum as long as it does not overlap the gate bus line 11a and the data bus line 16a. The auxiliary capacitance 21 is provided for the lower electrode 1 disposed below the reflective electrode 18a.
1b, an upper electrode 16d, and an insulating film 12 made of silicon nitride disposed therebetween. In the present embodiment, the capacitance value of the auxiliary capacitance 21 is set to be at least five times the capacitance value (electrostatic capacitance) of the liquid crystal cell 22 including the reflective electrode 18a, the common electrode 33, and the liquid crystal 40. is necessary. In the present embodiment, the lower layer electrode 11b and the upper layer electrode 16d of the auxiliary capacitance 21 are formed to have substantially the same size, as shown in FIG. 1, only slightly smaller than the reflection electrode 18a. Value is secured. The lower electrode 11b of each pixel arranged in the horizontal direction is electrically connected to each other by an auxiliary capacitance bus line 11c. The auxiliary capacitor bus line 11c is supplied with a voltage having the same potential as that of the common electrode 33, for example.

On the other hand, the CF substrate is configured as follows. That is, one surface side of the glass substrate 30 (FIG. 1)
On the lower surface side, a black matrix 31 that shields the gate bus line 11a, the data bus line 16a, and the area where the TFT 20 is formed is formed. The black matrix 31 is formed of a metal film such as Cr (chromium) or a black resin. On the lower surface side of the glass substrate 30, one of red, green and blue is provided for each pixel.
A color filter 32 of a color is formed. Below these color filters 32, a common electrode 34 made of a transparent conductor such as ITO is formed.

FIG. 4 shows one frame period (16) when the liquid crystal cell 22 is used alone, when the liquid crystal cell 22 is connected and connected to a storage capacitor twice as large, and when the liquid crystal cell 22 is connected to a storage capacitor five times as large. 0.7 ms). FIG. FIG. 4 also shows the waveforms of the scanning signal supplied to the gate bus line 11a and the data signal supplied to the data bus line 16a. Here, V _ID indicates the amplitude of the data signal, and V _com indicates the voltage supplied to the common electrode 33.

GH liquid crystal, polymer dispersed liquid crystal or DSM
The liquid crystal cell 22 using a liquid crystal having a specific resistance of 10 ¹⁰ Ωcm or less such as a liquid crystal has a voltage holding ratio of about 50% or less during one frame (16.7 ms). If it is about twice as large as 22, the voltage drops to about 83% of the supply voltage (display signal) at the end of one frame, causing flicker and burn-in. However, when the capacitance value of the auxiliary capacitance 21 is five times or more the capacitance value of the liquid crystal cell 22 as in the present embodiment, the voltage holding ratio becomes 90% or more, and the occurrence of flicker and image sticking can be prevented.

In the present embodiment, the liquid crystal 40 has a relative dielectric constant of about 7, which is substantially the same as the dielectric constant of the dielectric film (silicon nitride) of the auxiliary capacitor 21. The thickness of the dielectric film of the auxiliary capacitance 21 is about 0.3 μm, which is about 1/15 of the thickness of the liquid crystal layer.
If the area of 6d is the same as the pixel electrode 18a, the capacitance including the auxiliary capacitance 21 is as follows. This is about 15 times that of the liquid crystal cell 22 alone. In order to realize a capacitance value five times or more as compared with the capacitance of the liquid crystal cell 22, the electrode 11
The area of b, 16d is about 50% with respect to the pixel electrode 18a.
This is necessary.

Further, since there is a capacitive coupling between the gate electrode (gate bus line 11a) of the TFT 20 and the source electrode 16b, a problem that the pixel voltage fluctuates due to the scanning signal supplied to the gate bus line 11a occurs. I do. When the size of one side of the pixel electrode 18a is about 50 μm or less, the capacitance value between the gate and the source becomes relatively large as compared with the capacitance value of the liquid crystal cell 22, so that the fluctuation of the pixel voltage becomes large. When the auxiliary capacitance 21 is set to be about five times or more the capacitance value of the liquid crystal cell 22, the fluctuation of the pixel voltage due to the gate voltage can be suppressed.

In the liquid crystal display panel of the present embodiment, the auxiliary capacitance 21 having a capacitance value which is five times or more the capacitance of the liquid crystal cell 22 is connected in parallel to the liquid crystal cell 22. Although the voltage holding ratio is 50% or less, the voltage holding ratio in one frame period becomes about 90% or more. As a result, display without flicker and image sticking becomes possible, and a liquid crystal display device using a GH liquid crystal, a polymer dispersed liquid crystal, or a DSM liquid crystal can be put to practical use.

FIGS. 5 to 7 are sectional views showing a method of manufacturing the liquid crystal display device of the present embodiment in the order of steps. In addition, FIG.
FIG. 7 shows a cross section taken along the line BB in FIG. First, a method for manufacturing a TFT substrate will be described. As shown in FIG. 5A, a metal film of Cr or the like is formed on a glass substrate 10 to a thickness of about 150 nm, and the metal film is patterned by photolithography to form a gate bus line 11a, an auxiliary capacitor, and the like. The lower electrode 11b and the auxiliary capacitance bus line 11c are formed.

Next, as shown in FIG. 5B, a silicon nitride (SiN) film is formed on the entire upper surface of the glass substrate 10 as an insulating film 12 serving as a gate insulating film of the TFT 20 and a dielectric film of the auxiliary capacitance 21. ) Is deposited to a thickness of about 300 nm, and the gate bus lines 11a,
The lower electrode 11b and the auxiliary capacitance bus line 11c are covered.
Note that the material of the insulating film 12 is not limited to silicon nitride, and the insulating film 12 may be formed of silicon oxide (SiO) or another insulating material.

Thereafter, a polysilicon film 13 serving as a channel layer of the TFT 20 and a silicon nitride film 14 serving as a channel protection film of the TFT 20 are sequentially formed on the insulating film 12. The thickness of the polysilicon film 13 is, for example, 15 to 50 nm.
And the thickness of the silicon nitride film 14 is about 50 to 200 nm.
And Although the channel layer of the TFT 20 is formed of polysilicon in the present embodiment, it may be formed of amorphous silicon. However, in the present embodiment, since the auxiliary capacitance 21 having a large capacitance value is connected to the liquid crystal cell 22, the channel layer of the TFT 20 is
It is preferable to form the polysilicon with a high carrier mobility. The polysilicon film can be formed by a so-called laser annealing method in which after an amorphous silicon film is formed by a CVD method, the amorphous silicon film is irradiated with a laser beam.

Next, as shown in FIG. 5C, the uppermost silicon nitride film 14 is patterned by photolithography to form a channel protective film 14a. next,
As shown in FIG. 6A, an n ⁺ -type silicon film 15 serving as an ohmic contact layer of the TFT 20 is formed to a thickness of about 30 nm on the entire upper surface of the glass substrate 10. Thereafter, Ti (titanium) / Al is formed on the n ⁺ silicon film 15.
(Aluminum) / Ti (titanium) are sequentially stacked to form a conductive film 16 having a three-layer structure of Ti, Al, and Ti.

Next, as shown in FIG.
Conductive film 16 and n ⁺Type silicon film 15
Patterning the data bus line 16a, TFT
20 source electrodes 16b and drain electrodes 16c,
Then, the upper electrode 16d of the auxiliary capacitance 21 is formed. Then figure
As shown in FIG. 6C, the entire upper surface of the glass substrate 10 is covered with nitrogen.
Protective film 17 made of silicon nitride having a thickness of about 100 to 600 nm
Formed to a thickness of The predetermined position of the protective film 17
Then, contact holes 17a and 17b are formed. In addition,
Forming a resin layer having undulations on the surface on the protective film 17
You may.

Next, as shown in FIG. 7A, an Al film 18 is formed on the entire upper surface of the glass substrate 10 to a thickness of about 70 nm. The Al film 18 is formed in the contact hole 17
Source electrode 16b and upper electrode 16 via a and 17b.
d is electrically connected. Then, the Al film 18 is patterned to form a reflective electrode (pixel electrode) 18a as shown in FIG. 7B. Thus, a TFT substrate is completed.

Next, a method of manufacturing a CF substrate will be described. First, a Cr film is formed on one surface (the lower surface in FIG. 1) of the glass substrate 30, and the Cr film is patterned by photolithography to form a black matrix 31. Then, after applying a red photosensitive resin, the red photosensitive resin is patterned to form a red color filter 32 in a red pixel region. Similarly, using a green photosensitive resin and a blue photosensitive resin, green and blue color filters 32 are formed in the green pixel region and the blue pixel region by a photolithography method.

Next, ITO is sputtered on the color filters 32 to form a common electrode 33. Thus, a CF substrate is completed. Next, a spacer (not shown) for maintaining a constant distance between the TFT substrate and the CF substrate is arranged, and the TFT substrate and the CF substrate are joined outside the display area. Then, after injecting the liquid crystal 40 between the TFT substrate and the CF substrate from the liquid crystal injection port, the liquid crystal injection port is sealed with a resin. Thus, the liquid crystal display panel of the present embodiment is completed.

According to the above-described manufacturing method, the lower electrode 11b of the auxiliary capacitance 21 is formed simultaneously with the gate bus line 11a, and the upper electrode 16 of the auxiliary capacitance 21 is formed simultaneously with the data bus line 16a, the source electrode 16b and the drain electrode 16c.
Since d is formed, an increase in the number of steps is avoided. In addition,
In this embodiment, the case where the present invention is applied to a reflective liquid crystal display panel has been described. However, the present invention can be applied to a transmissive liquid crystal display panel. In that case, the auxiliary capacity 21
Lower electrode 11b, upper electrode 16d and pixel electrode 1
8a is formed of a transparent conductor such as ITO.

(Second Embodiment) FIG. 8 shows a second embodiment of the present invention.
FIG. 9 is a plan view showing the liquid crystal display panel of the embodiment, and FIG. 9 is an equivalent circuit diagram of one pixel of the liquid crystal display panel.
In this embodiment, since the configuration of the CF substrate is basically the same as that of the first embodiment, illustration and description of the CF substrate are omitted. In FIG. 8, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the liquid crystal display panel of this embodiment, a TFT 41 for writing data, a TFT 42 for driving a liquid crystal cell, and an auxiliary capacitor 43 are provided for each pixel. In the liquid crystal display panel of the present embodiment, a constant voltage supply bus line 11d and an auxiliary capacitance bus line 11e are arranged in parallel with the gate bus line 11a. A constant voltage is supplied to the constant voltage supply bus line 11d.

The data writing TFT 41 uses a part of the gate bus line 11a as a gate electrode, the drain electrode 16b is connected to the data bus line 16a, and the source electrode 16c is connected to the upper layer electrode 16g of the storage capacitor 43. Further, the gate electrode 11g of the liquid crystal cell driving TFT 42 is connected to the upper electrode 16g of the auxiliary capacitance 43 via the contact hole 17c, and the drain electrode 16e.
Is connected to a constant voltage supply bus line 11d via a contact hole 17d, and the source electrode 16f is connected to a reflective electrode (pixel electrode) 18a constituting the liquid crystal cell 33 via a contact hole 17e. Auxiliary capacity 43
Is composed of an upper electrode 16g connected to the source electrode 16c of the TFT 41 and the gate electrode 11g of the TFT 42, a lower electrode 11f connected to the auxiliary capacitance bus line 11e, and a dielectric film formed therebetween. ing. The other end of the auxiliary capacitance is maintained at the same potential as the common electrode.

The constant voltage supply line 11d, the auxiliary capacitance bus line 11e, the lower electrode 11f of the auxiliary capacitance 43, and the TFT
The gate electrode 11g of 42 is formed in the same wiring layer (first wiring layer) as the gate bus line 11a. That is, the gate bus line 11a, the constant voltage supply line 11d, the auxiliary capacitance bus line 11e, and the auxiliary capacitance 43
Lower electrode 11f and gate electrode 11g of TFT 42
Are formed by patterning the same conductive film.

The source electrode 16b and the drain electrode 16c of the TFT 41, the upper layer electrode 16g of the auxiliary capacitance 43, and the source electrode 16f and the drain electrode 1 of the TFT 42
6e is the same wiring layer as the data bus line 16a (second wiring layer).
Wiring layer). By providing a thick resin layer on the protective film, it is possible to form the reflective electrode 18a also on the TFT 42 and the upper electrode 16g.

In this embodiment, the liquid crystal cell 44 is a TFT
The charge corresponding to the voltage of the auxiliary capacitance 43 connected to the gate electrode of the TFT 42 is connected to the TFT 4.
2 to the liquid crystal cell 44. Therefore, even if the voltage holding ratio of the liquid crystal cell 44 is low, occurrence of flicker and image sticking can be avoided. In the present embodiment, a TFT is provided between the storage capacitor 43 and the liquid crystal cell 44.
Since the connection is made, the leakage of the electric charge stored in the auxiliary capacitance 43 is extremely small. Therefore, the size of the auxiliary capacitance 43 can be reduced.

Note that the liquid crystal display panel of this embodiment is
Multi-gradation display is possible by dividing one frame into a plurality and performing so-called field sequential driving for controlling the ON time in one frame. (Supplementary Note 1) An active matrix liquid crystal display panel in which liquid crystal cells having a voltage holding ratio of 50% or less in one frame (16.7 ms) are arranged in a matrix, and the capacitance of the liquid crystal cells is five times or more. A liquid crystal display panel having a capacitance value and comprising an auxiliary capacitance connected to the liquid crystal cell.

(Supplementary Note 2) The liquid crystal display panel according to Supplementary Note 1, wherein a capacitance electrode forming the storage capacitor is arranged at a position overlapping with a pixel electrode forming the liquid crystal cell. (Supplementary note 3) The liquid crystal display panel according to supplementary note 2, wherein the capacitance electrode is formed of a transparent conductor. (Supplementary Note 4) The lower electrode of the auxiliary capacitance is formed on the same wiring layer as the gate electrode of the TFT, and the upper electrode of the auxiliary capacitance is formed on the same wiring layer as the source electrode and the drain electrode of the TFT. 3. The liquid crystal display panel according to claim 1.

(Supplementary Note 5) An active matrix liquid crystal display panel in which liquid crystal cells having a voltage holding ratio of 50% or less in one frame (16.7 ms) are arranged in a matrix, and a plurality of liquid crystal cells to which a scanning signal is supplied are provided. A gate bus line, a plurality of data bus lines to which data signals are supplied, an auxiliary capacitor and a pixel electrode formed in each pixel region surrounded by the gate bus line and the data bus line, and a gate electrode. Are connected to the gate bus line, a drain transistor is connected to the data bus line, and a source electrode is connected to the storage capacitor. A first transistor is connected to the gate electrode. A gate electrode is connected to a source electrode of the first transistor. And a second transistor having a drain electrode connected to the constant voltage source and a source electrode connected to the pixel electrode. The liquid crystal display panel, characterized in that.

(Supplementary note 6) The liquid crystal cell according to Supplementary note 1 or 5, wherein any one kind of liquid crystal selected from the group consisting of GH liquid crystal, polymer dispersed liquid crystal, and DSM liquid crystal is used. LCD panel. (Supplementary Note 7) The liquid crystal display panel according to Supplementary Note 1 or 5, wherein a liquid crystal having a specific resistance of 10 ¹⁰ Ωcm or less is used for the liquid crystal cell.

[0046]

As described above, according to the present invention, an auxiliary capacitor having a capacitance value five times or more the capacitance of the liquid crystal cell is connected to the liquid crystal cell. It is possible to prevent flicker and burn-in of a liquid crystal display panel using a liquid crystal having a low voltage holding ratio such as a liquid crystal or a DSM liquid crystal.

According to another aspect of the present invention, the first transistor connected between the data bus line and the storage capacitor, the gate electrode is connected to the storage capacitor, and the source electrode is connected to the pixel electrode. And a second transistor having a drain electrode connected to a constant voltage source, so that the GH liquid crystal,
It is possible to prevent flicker and image sticking of a liquid crystal display panel using a liquid crystal having a low voltage holding ratio such as a polymer dispersed liquid crystal or a DSM liquid crystal.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a TFT substrate of the liquid crystal display panel.

FIG. 3 is an equivalent circuit diagram of one pixel of the liquid crystal display panel.

FIG. 4 shows a case where a liquid crystal cell is used alone,
One frame period (1) when a double storage capacitor is connected and connected, and when a storage capacitor five times the storage capacitor is connected to a liquid crystal cell.
It is a figure which shows the voltage holding ratio of (6.7 ms).

FIG. 5 is a sectional view (part 1) illustrating the method for manufacturing the liquid crystal display of the present embodiment.

FIG. 6 is a sectional view (part 2) illustrating the method for manufacturing the liquid crystal display of the present embodiment.

FIG. 7 is a sectional view (part 3) illustrating the method for manufacturing the liquid crystal display of the present embodiment.

FIG. 8 is a plan view showing a liquid crystal display panel according to a second embodiment of the present invention.

FIG. 9 is an equivalent circuit diagram of one pixel of the liquid crystal display panel.

[Explanation of symbols]

 Reference Signs List 10: glass substrate (TFT substrate), 11a: gate bus line, 11b, 11f: lower electrode, 11c, 11e: auxiliary capacitance bus line, 11d: constant voltage supply bus line, 11g: gate electrode, 12: insulating film, 13 ... polysilicon film, 14 ... silicon nitride film, 14a ... channel protective film, 16a ... data bus line, 16b ... source electrode, 16c ... drain electrode, 16d, 16g ... upper layer electrode, 17a, 17b, 17c ... contact hole, 18 ... Al film 18a ... Reflection electrode (pixel electrode), 20,41,42 ... TFT, 21,43 ... Auxiliary capacitance, 22,44 ... Liquid crystal cell, 30 ... Glass substrate (CF substrate), 31 ... Black matrix, 32 ... Color filter, 33: Common electrode, 40: Liquid crystal.

Continued on the front page F term (reference) 2H092 JA26 JA35 JA44 JB07 JB33 JB42 JB52 JB57 JB63 JB69 KA04 KA05 KA12 KA18 KB13 KB24 MA07 MA30 NA01 PA08 QA08 QA15 5F110 BB02 CC07 DD02 EE04 FF02 FF03 GG03 GG03 GG03 GG03 NN03 NN12 NN14 NN16 NN24 NN46 NN72 NN73 PP03

Claims (5)

[Claims] 1. A voltage holding ratio in one frame is 50%.
An active matrix type liquid crystal display panel in which the following liquid crystal cells are arranged in a matrix, having a capacitance value of 5 times or more of the capacitance of the liquid crystal cell, and having an auxiliary capacitance connected to the liquid crystal cell. A liquid crystal display panel characterized by the above-mentioned. 2. The liquid crystal display panel according to claim 1, wherein a capacitance electrode forming the storage capacitor is arranged at a position overlapping with a pixel electrode forming the liquid crystal cell. 3. The liquid crystal display panel according to claim 2, wherein said capacitance electrode is formed of a transparent conductor. 4. A voltage holding ratio in one frame is 50%.
An active matrix type liquid crystal display panel in which the following liquid crystal cells are arranged in a matrix, comprising: a plurality of gate bus lines to which a scanning signal is supplied; a plurality of data bus lines to which a data signal is supplied; A storage capacitor and a pixel electrode respectively formed in each pixel region surrounded by a bus line and the data bus line; a gate electrode connected to the gate bus line; a drain electrode connected to the data bus line; A first transistor having an electrode connected to the storage capacitor; a gate electrode connected to a source electrode of the first transistor; a drain electrode connected to a constant voltage source; and a source electrode connected to the pixel electrode. A liquid crystal display panel comprising a second transistor. 5. A liquid crystal display device comprising: a guest-host liquid crystal;
5. The liquid crystal display panel according to claim 1, wherein any one kind of liquid crystal selected from the group consisting of a polymer dispersed liquid crystal and a dynamic scattering liquid crystal is used.