JP3385530B2 - Liquid crystal display device and driving method thereof - Google Patents

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 a driving method thereof, and more particularly to an active matrix type liquid crystal display device and a driving method thereof.

[0002]

2. Description of the Related Art A conventional basic liquid crystal drive circuit is shown in FIG.
As shown in a block diagram in FIG. 1, a video signal 64 such as a video signal is transmitted via the control circuit 63 to the data driver 61.
And the scanning line drive circuit 62, and the liquid crystal display panel 6
It drives 0.

A conventional display method of a liquid crystal display device using such a drive circuit is a method of sequentially switching 60 screens at a frame frequency of 60 Hz as shown in FIG. That is, in the first frame, the first display screen 1
The second display screen 21 is driven in the first and second frames, the third display screen 31 is driven in the third frame, and the fourth display screen 41 is driven in the fourth frame.

Further, as shown in FIGS. 49 and 50, the polarity inversion method of each display cell is also a method of switching the polarity every other screen. For example, as shown in FIG. 49, the first
And the polarity pattern 1 of the third display screens 11 and 31
11 and 311 are the same, and the pattern thereof has a polarity opposite to that of the second and fourth display screens 210 and 410. Focusing on the polarity of the cell at the upper left of each pattern, the order is +-+-, which is the drive voltage Vd whose polarity is inverted with respect to the common potential Vc for each frame as shown in FIG. It is realized by applying to the data electrodes of the liquid crystal display panel.

[0005]

The conventional liquid crystal display device employs a system of sequentially switching screens as shown in FIG. 48. One screen is displayed for 1/60 second if the frame frequency is 60 Hz. Holding that screen.

If the next screen comes in here, the human eye recognizes both the previous screen and the previous screen, which causes the afterimage. This afterimage feeling cannot be eliminated no matter how much the response speed of the liquid crystal is improved.

Further, in the operation of the liquid crystal, the direction in which a voltage is applied is proportional to the reciprocal of the applied voltage value. Therefore, when every gradation exists on one screen like a natural image, the image is distorted. It has the drawback of becoming

Further, when a normally white (NW) type optical birefringence compensation (OCB) type liquid crystal display device is used in a conventional liquid crystal display device, when white screens are continuously displayed, the bend deformation collapses to cause a display. There was a drawback that the disturbance of

[0009]

According to the present invention, a liquid crystal display is provided.
In the driving method of the display device, data in each frame
The screen and the black screen are divided into two parts above and below each
Liquid crystal characterized by repeated display for each frame
A method for driving a display device can be obtained. This drive method smells
The black signal and the data signal within the writing time of one scanning line.
By selecting the rise time of each scan line individually,
Characterized by writing separate signals to the upper part of the surface and the lower part of the screen
To do.

[0010]

[0011]

[0012]

[0013]

Another feature is that a black signal is output when the polarity of the data changes to improve the time constant of the data wiring. Here, it is also characterized in that the rising signal of the scanning line for writing the data signal is overlapped with the black data portion to precharge the liquid crystal.

[0015]

[0016]

Further, the black display and the data display are repeated for every three data lines (R, G, B) of three colors, and in the next screen, the portions for displaying the data screen and the black screen are shifted by three lines. A liquid crystal display device and a method for driving the liquid crystal display device are also obtained.

Furthermore, in the liquid crystal display device and the method of driving the same, it is possible to perform black display and data display for every other pixel on a certain screen, and to invert the pixels of the data screen and the portion for displaying the black screen on the next screen. A characteristic liquid crystal display device and a driving method thereof can also be obtained.

In the method of driving the liquid crystal display device, the polarity of the liquid crystal is inverted every 2n (n = 1, 2, 3 ...) Frames, and the polarity is inverted every two data lines. And

In addition, a liquid crystal display device is also provided which has means for dividing a data screen and a black screen in each frame vertically into two or more parts and repeatedly displaying each for each frame. To be This liquid crystal display device is also characterized in that the scanning line driving circuit is divided into two or more parts and each of them is controlled. Further, this liquid crystal display device is characterized in that a data set circuit is provided after the latch circuit in the data driver to use a data driver capable of setting a black screen for an arbitrary time by inputting a SET pulse.

The above liquid crystal display device is characterized in that light is reflected and reused in a black display state.
In this liquid crystal display device, the polarizing plate used is λ / 4
It is characterized by being constituted by a retardation plate and a reflective layer of cholesteric liquid crystal.

Further, this liquid crystal display device is characterized in that a phase difference compensating plate or a brightness improving film for expanding the viewing angle is combined.

Furthermore, in these liquid crystal display devices, a liquid crystal display device is obtained in which the liquid crystal display mode to be combined is a normally white mode, and further, in this liquid crystal display device, the normally white mode is used. Mode liquid crystal cell is twist nematic liquid crystal cell, horizontal electric field type liquid crystal cell, vertical alignment type liquid crystal cell,
It is also characterized by being either an optical birefringence compensation type liquid crystal cell or an electrical birefringence compensation type liquid crystal cell.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, reference examples and embodiments of the present invention will be described in detail with reference to the drawings.

Reference Example 1 Reference Example 1 is characterized in that the display screen is repeated for each frame, that is, the data screen and the black screen, as shown in FIG. For example, the data screen 11 in the first frame, the black screen 22 in the second frame, the data screen 31 in the third frame, the fourth screen
In the frame, it is driven like a black screen 42.

Further, in the driving method, as shown in FIGS. 2 to 4, the polarity of the driving voltage Vd applied to the liquid crystal is inverted every two frames, that is, every two screens (data screen and black screen). By providing a frame memory on the side of the drive circuit module, display can be performed at a speed twice or more as high as a normal frame frequency (50 Hz to 80 Hz).

FIG. 6 shows a block diagram of the drive circuit of the first reference example . The difference from the conventional basic drive circuit (FIG. 51) is that the video signal 64 is fetched into the control circuit 63, the output thereof is controlled and supplied to the data driver 61 through the switching means 67. Details of the data driver 61 are shown in FIG. 7, and this driver has been used conventionally.

As shown in FIG. 6, the drive module of Reference Example 1 stores information for one screen in the frame memory 65,
The data is read out at about twice the speed and the write data screen is displayed on the liquid crystal panel 60. Next, the control circuit 63 writes all the data as black screen data on the liquid crystal panel to display a black screen. By repeating this operation, the data screen and the black screen can be alternately repeated.

However, this is a conventional frame frequency 60.
If it is performed at Hz, 30 data screens and 30 black screens are repeated, which may cause flicker.
Therefore, the flicker can be suppressed by providing the frame memory 65 in the module so that the frame frequency is doubled.

When frame polarity inversion, which is the polarity inversion of a normal liquid crystal panel, is used for the display system of Reference Example 1 , when the data screen is + polarity, all black screens are -polarity and the DC component is always in the negative polarity. It is applied to the liquid crystal (when the data screen is-, a DC component of + polarity is generated).

Therefore, as shown in FIG. 2, it is possible to cancel the DC component by arranging the data screen and the black screen as one set and reversing the polarity for each set.

In FIG. 2A, the polarity patterns 111 and 221 of the data frame 11 of the first frame and the black screen 22 of the second frame are the same, and the data screen 31 of the third frame and the black screen of the fourth frame are the same. The 42 polarity patterns 310 and 420 are in the opposite polarity to the first and second frames. In FIG. 2B, the first
The polar patterns 111 and 421 of the data screen 11 of the frame and the black screen 42 of the fourth frame are the same,
The polarity patterns 220 and 310 of the black screen 22 of the second frame and the data screen 31 of the third frame are opposite in polarity to those of the first and fourth frames.

Here, changes in drive voltage when attention is paid to the polarities of the patterns surrounded by thick lines on the upper left of FIGS. 2A and 2B are shown in correspondence with FIGS. 3 and 4, respectively. When the data screen is + with respect to the common potential Vc, the next black screen is +
Then, the DC component can be canceled in four screens by setting the polarities of the next data screen and the black screen to-.

This polarity is 4 as shown in FIGS. 3 and 4.
It suffices if each set of data screens and black screens in the screen has both positive and negative polarities. In this case, the polarity reversal is performed every two screens. However, if the polarity inversion is performed every 2n (n = 1, 2, 3 ...) Frames, the DC component is canceled at the time when the 4n screen is completed.
It is not limited to two-frame inversion.

By repeating the above-described display, the data screen is displayed intermittently (hereinafter referred to as impulse), and a moving image display equivalent to that of a CRT can be obtained.

Further, the response speed of the conventional liquid crystal is 1 / when the voltage is applied to the liquid crystal (0 V → XV) as shown in FIG.
(Proportional drive voltage) and voltage release direction (X
(V → 0V) hardly depends on the driving voltage. This corresponds to the following equations (1) and (2), which are basic equations for the liquid crystal response speed.

Τon (voltage application side) = (γ * d * d) / (εo * εa (V * V−Vc * Vc)) (1) τoff (voltage release side) = (γ * d * d) / (Π * π * K) (2) where γ: viscosity of liquid crystal d: gap of liquid crystal cell εo: vacuum permittivity εa: difference in permittivity of liquid crystal V: drive voltage Vc: threshold voltage of liquid crystal K: liquid crystal Therefore, when a moving image is displayed, a portion having a fast response speed and a portion having a slow response speed are mixed, and the image is perceived by human eyes as a distorted afterimage.

In Reference Example 1 , by inserting the black screen between the data screens, only the voltage open side of the above contents is used, the response speed is constant regardless of the screen, and the screen is stable and there is no afterimage feeling. can get. Therefore, in the present invention, it is possible to display a moving image without using the liquid crystal mode having a particularly fast response speed.

By carrying out the display method of Reference Example 1 , the following effects (a) to (f) can be obtained. (A) By performing the display of FIG. 1, a moving image display equivalent to that of a CRT can be obtained. (B) There is no limitation on the method of forming the auxiliary capacitance of the liquid crystal cell. (C) By eliminating the direct current component applied to the liquid crystal, a highly reliable liquid crystal display device can be obtained. (D) The same response speed can be obtained in any gradation display. (E) By performing the operation at double speed or more, it is possible to obtain a display in which flicker is inconspicuous. (F) It is possible to change the ratio of the data screen and the black screen.

Reference Example 2 Reference Example 2 will be described below.

As shown in FIG. 8 and FIG. 9 as a block diagram of the drive circuit module of Reference Example 2 of the present invention, a common electrode (COM electrode) (not shown) of the liquid crystal display panel 60 is shown.
In addition, the COM voltage generating circuit 66 controlled by the control circuit 63 applies a waveform as shown in FIGS.

FIG. 13 shows a circuit diagram of an active element combined with the second reference example . The display method in this reference example is for reference
Similar to the example 1, the data screen and the black screen are alternately displayed. In the reference example 1, the data written in the frame memory is written at about double speed, whereas in the reference example , as shown in FIG. 13, the auxiliary capacitance (hereinafter Csc) 93 is added to the gate wiring electrode 91. Is performed by using a gate storage type liquid crystal panel in which In the figure, 92 is a drain wiring, 90 is a liquid crystal cell, 95 is a gate-source parasitic capacitance Cgs, 96 is a common electrode, and 900 is
Indicates a TFT.

In this reference example , the driving is realized by any of the configurations shown in the driving circuit module block diagram of FIG. 8 or FIG. That is, the concept of the drive waveform applied to the common electrode of the liquid crystal display panel 60 is that the signal of the common electrode (hereinafter referred to as the COM electrode) is displayed outside the display section (the blanking section referred to as CRT) as shown in FIGS. ), The black screen is inserted between the data screens by swinging at the voltage V1 shown in the following equation (3).

V1 = ((CLC + Csc) / Csc) × Vcr (3) V1: Common electrode signal amplitude Vcr: Liquid crystal cell black signal amplitude CLC: Liquid crystal capacitance (during black display) Csc: Auxiliary capacitance (gate storage Swinging the COM electrode with the amplitude of V1 enables writing of charges in the liquid crystal cell capacitance CLC through Csc connected to the virtually grounded gate electrode.

FIG. 10 shows one frame (frame frequency 6
In case of 0Hz, about 16.7msec), the COM electrode is +,
This is the case of swinging in both negative polarities.

FIG. 11 shows the case where the polarity of the COM electrode is changed to the same polarity as the video signal polarity within the frame, and FIG. 12 shows the case where the polarity of the COM electrode is changed to the opposite polarity to the video signal polarity within each frame. .

This reference example cannot be applied to a common (COMMON) storage system in which a COM electrode is provided on the TFT substrate side and an auxiliary capacitance is formed between the pixel electrode and the pixel electrode through an insulating film.

In addition to the effect of the first reference example, the second reference example has the effect that a frame memory can be omitted as a liquid crystal display device as shown in FIG.

[0049] (Embodiment Example 1) Next, embodiment 1 of the present invention will be described.

FIG. 14 is an explanatory diagram of the first embodiment of the present invention, and FIG. 15 is a module block diagram of the first embodiment.
Block diagram of a data driver used in Embodiment 1 of FIG. 16 shows a driving timing diagram of Embodiment 1 of the FIGS. 17 to 20.

In the present embodiment, as shown in FIG. 14, the display screen in each frame is divided into upper and lower parts, and the data screen and the black screen are repeated with each of them as one unit. That is, in the n frame, if the upper half is the data screen nD and the lower half is the black screen nB, (n +
In the 1) frame, the upper half is the black screen (n + 1) B and the lower half is the data screen (n + 1) D (n is an integer). This can be realized by the drive circuit module block diagram shown in FIG.

This will be described with reference to the timing charts 17 and 18. Here, OE1 and OE2 in FIG. 15 are output enable, SP1 and SP2 are start pulses, and C
LK is a clock signal, and O1 and O2 are liquid crystal panels 60.
And second scanning line drive circuit 6 for driving the scanning lines of
21 and 622, and DO1 indicates the output of the data driver 611.

FIG. 15 is characterized in that the scanning line driving circuit is divided into two or more circuits and each circuit is controlled by the control circuit 631. Further, as a data driver 611, FIG.
6 uses a data driver as shown in the block diagram. This data driver ANDs each output after latching
When the circuit is connected and the SET pulse is low (hereinafter L), all outputs are set to L to output the black screen voltage, and when the SET pulse is high (hereinafter H), the data stored in the latch is output. It is a driver that outputs a data screen. This driver is used to realize the output waveform of DO1 in the timing explanatory diagrams of FIGS.

First, the operation will be described with reference to FIG. DO
The output of 1 is divided into a data signal portion and a black signal portion within one scanning line. The upper scanning line drive circuit 621 is controlled by OE1, SP1 and CLK so that only the data portion is written in the upper scanning line output O1, and the lower scanning line output O2 is written in OE2 so that the black signal portion is written. The lower scanning line drive circuit 622 is controlled by SP2 and CLK. At this time, the ratio of the data signal and the black signal portion is determined by the data driver 61.
It is possible only by changing the ratio of L and H of the SET pulse to 1. FIG. 17 shows a case where the black signal portion is short. In this case, SP2 input to the lower scanning line drive circuit 622.
A black signal of the same polarity can be written in the liquid crystal by activating every two CLKs.

By this method, even a black signal for a short time can be written in the liquid crystal, so that the time for the data signal portion can be lengthened.

In FIG. 18, a black signal is written in the upper part,
It is a diagram showing the timing of writing the data signal in the lower part.

In the above contents, the timing of outputting the black signal after the data signal with the same polarity of the data signal and the black signal is shown. Separately from this, the timing of raising the black signal before the data signal is shown in FIGS. 19 and 20.
In this case, since the polarity is the same as that of the data, the same effect as the precharge can be obtained.

Referring to FIG. 19, in this case, the upper scanning line drive circuit 621 operates to write a data signal in the liquid crystal, and the lower scanning line drive circuit 622 operates to write a black signal in the liquid crystal. . As described above, since the black signal and the data signal have the same polarity, the upper scanning line drive circuit 621
OE1 is controlled to write a part of the black signal in the liquid crystal. As a result, the liquid crystal is precharged to improve writing.

It is necessary to confirm that the time for performing this precharge does not affect the data display (excessive precharge may reduce the luminance in white display).

Further, as shown by the waveform of DO1 in FIG. 19, there is an advantage that the black signal is output when the polarity of the data changes and the time constant of the data wiring is improved because the data polarity changes. .

FIG. 20 is a diagram for explaining the operation timing of writing a black signal in the liquid crystal by the upper scanning line drive circuit 621 and writing a data signal by the lower scanning line drive circuit 622.
In this case, the scanning line signal output for writing the black signal has the same polarity every two scanning lines, and the content thereof is the same as that described with reference to FIGS. 17 and 18.

The present embodiment has the following effects as compared with the first embodiment.

(I) No frame memory is required.

(Ii) The double speed display can be realized in a pseudo manner.

(Iii) It can be realized without increasing the number of data drivers and scanning line driving circuits.

(Iv) The liquid crystal panel can be designed (especially the writing characteristic to the liquid crystal) by the same design as the conventional one.

[0067] (Embodiment Example 2) Next, Embodiment 2 of the present invention will be described.

FIG. 21 shows a display system explanatory diagram of the second embodiment of the present invention. FIG. 22 shows the polarity reversal method of the present embodiment.

In the present embodiment, on a certain display screen n, every other scanning line, for example, odd-numbered scanning lines are data display nD, even-numbered scanning lines are black display nB, and the next display screen (n + 1) is displayed. Then, odd-numbered scan lines are displayed in black (n + 1) B, and even-numbered scan lines are displayed in data (n
+1) D. By repeating this display, a moving image display equivalent to that of Reference Example 1 is obtained. Also in this embodiment, as shown in FIG. 22, by inverting the polarity for every 2n (n = 1, 2, 3 ...) Screen, the liquid crystal can be driven without applying a direct current. In the illustrated example, the polar patterns 131 and 241 of the display screens 13 and 24 in the first and second frames are the same, and the polar patterns 3 of the display screens 33 and 44 in the third and fourth frames are the same.
30 and 440 are inverted.

The present embodiment example has the following effects as compared with the reference example 1.

(I) Suitable for displaying interlaced signals such as NTSC.

(Ii) It is not necessary to have a frame memory.

(Iii) It can be realized without increasing the number of data drivers and scanning line driving circuits.

(Iv) The liquid crystal panel can be designed (especially the writing characteristic to the liquid crystal) by the same design as the conventional one.

[0075] The embodiment 3 of the present invention (Embodiment Example 3) will be described below.

FIG. 23 is an explanatory view of a display system according to the third embodiment of the present invention. FIG. 24 shows the polarity reversal method of the present embodiment.

In this embodiment, the data display nD and the black display nB are continuously arranged every three data lines on a certain display screen n, and the black display (on every third data line is displayed on the next display screen (n + 1)). The (n + 1) B and the data display (n + 1) D are continuously arranged. By repeating this display, a moving image display equivalent to that of Reference Example 1 is obtained.

In this embodiment, as shown in FIG. 24, the polarity is inverted every 2n (n = 1, 2, 3 ...) Screens and at the same time, the polarity is inverted every two data lines. There is a need. This makes the data line 1 as before.
If the polarity is reversed every other line, the polarity will be biased to either + or-when focusing on the scanning line direction, and the common electrode line or the gate line to which Csc is connected is biased in a biased direction. Will end up. Therefore, the voltage applied to the liquid crystal has asymmetry, which causes display defects such as flicker and crosstalk. Therefore, every two data lines cancel the DC component and 2n (n = 1, 2,
3 ...) The polarity can be inverted for each screen at the same time, and the liquid crystal can be driven without applying a direct current.

In the illustrated example, the polarity patterns 151 and 261 of the display screens 15 and 26 in the first and second frames are the same, and the polarity patterns 350 and 460 of the display screens 35 and 46 in the third and fourth frames are reversed. is doing.

The present embodiment example has the following effects as compared with the reference example 1.

(I) It is not necessary to have a frame memory.

(Ii) It can be realized without increasing the number of data drivers and scanning line driving circuits.

(Iii) The liquid crystal panel can be designed (especially the writing characteristic to the liquid crystal) by the same design as the conventional one.

[0084] (Embodiment Example 4 Embodiment) Next, embodiment 4 of the present invention will be described.

FIG. 25 is an explanatory view of a display system according to the fourth embodiment of the present invention. FIG. 26 shows the polarity reversal method of this embodiment.

In the present embodiment, in a certain display screen n, data display nD and black display nB are displayed every three data lines for odd-numbered scanning lines, and data display is performed for even-numbered scanning lines. A black display nB and a data display nD are displayed every three lines to give a so-called checkered pattern. On the next display screen (n + 1), the data display and black display of the previous screen are reversed and displayed. That is, black display (n + 1) B and data display (n +) are displayed for every third data line with respect to the odd-numbered scanning line.
1) D is displayed, and data display (n + 1) D and black display (n + 1) are displayed for every three data lines with respect to even-numbered scanning lines.
Display B and.

In the above example, the display is made different every three data lines, but this is because it is premised on the correspondence to the color data signals of three colors. If the display is made different for every other data line, it is possible to realize a checkerboard pattern display in which data display and black display are repeated for each pixel.

As described above, the same moving image display as that of the reference example 1 can be obtained by the display method of the fourth embodiment.

Further, also in the fourth embodiment, the embodiment is described.
As described in 3 , the 2n (n = 1,
(2, 3 ...) It is necessary to invert the polarity for each screen and at the same time invert the polarity for every two data lines. As a result, the liquid crystal can be driven without applying a direct current. In the illustrated example, the display screen 17 in the first and second frames
And 28 have the same polarity pattern 171 and 281 and the polarity patterns 370 and 480 of the display screens 37 and 48 in the third and fourth frames are inverted.

The present embodiment example has the following effects as compared with the reference example 1.

(I) It is not necessary to have a frame memory.

(Ii) It can be realized without increasing the number of data drivers and scanning line driving circuits.

(Iii) The liquid crystal panel can be designed (especially the writing characteristic to the liquid crystal) by the same design as the conventional one.

An example of an embodiment of the liquid crystal cell will be described below.

FIG. 27 is an explanatory diagram of the basic operation of the liquid crystal cell to which the driving method of the first to fourth embodiments is applied, and FIGS. 28 to 3
FIG. 7 shows a constitutional example of a liquid crystal cell combined with the present invention.

The basic operation of the liquid crystal cell combined with the present invention will be described with reference to FIG. Embodiment 1 of the present invention
The display methods up to 4 are aimed at obtaining a moving image display similar to that of a CRT, but since any of the embodiments is a method of inserting a black screen between data screens, the screen brightness may be reduced. The present method can be realized with a conventional liquid crystal cell configuration, but it is desirable to combine the liquid crystal cell of the present invention described below in order to compensate for this decrease in screen brightness.

Light incident on the liquid crystal cell becomes linearly polarized light 531 when passing through the first polarizing plate 53. When the liquid crystal cell 80 is a twisted nematic (TN) cell, the polarization state is twisted by 90 degrees in the white display state (reference numeral 581), and in the black display state, the polarization state remains unchanged. Pass through. Here, when passing through the liquid crystal cell 80, λ / 4 in a direction inclined by about 45 degrees from the polarization state of light.
When the optical film 74 for generating the phase difference is inserted, the right circularly polarized light (or left circularly polarized light) indicated by reference numeral 741 in the white display state and the left circularly polarized light (or right circularly polarized light) indicated by the reference numeral 742 in the black display state are obtained. Become.

By providing the cholesteric liquid crystal layer 75 capable of selectively reflecting the left circularly polarized light (or the right circularly polarized light) after the light converted into the circularly polarized light, the light is reflected in the black display state, and this reflection The generated light is further converted into linearly polarized light through the λ / 4 retardation plate and returned to the inside of the liquid crystal cell and further to the backlight (B / L) light source for reuse. In the white state, light passes through the cholesteric layer in its polarized state (reference numeral 751).

The structure of a liquid crystal cell using this method will be described with reference to the drawings. FIG. 28 is a diagram in which the λ / 4 plate 74 and the cholesteric layer 75 are formed outside the color filter (CF) substrate 71. Well-known RGB color filters are formed on the inner surface of the CF substrate 71. Then, the TFT substrate 51 is arranged across the liquid crystal layer 80, and the polarizing plate 53 is formed on the outer side of the substrate 51 so that light from a light source 800 such as a backlight enters the polarizing plate 53. ing. 80
Reference numeral 5 represents a liquid crystal molecule.

In FIG. 29, a cholesteric layer 75 is sandwiched between two λ / 4 plates 74, and a polarizing plate 7 is formed on the cholesteric layer 75.
3 is provided. In the case of FIG. 29, circularly polarized light that has passed through the cholesteric layer 75 in white display is further added to the λ / 4 plate 74.
By converting to linearly polarized light and passing through the polarizing plate 73, the black display is improved and the viewing angle and the contrast are improved as compared with FIG.

FIG. 30 shows a system in which the λ / 4 plate 74 and the cholesteric layer 75 are provided below the CF substrate 71 to further improve the reflection efficiency. In FIG. 28, since light that has once passed through the CF layer is reflected and then made incident on the CF layer again, there is a possibility that the luminance may be reduced and the light reuse efficiency may be reduced. Take measures by installing it before the incident.

FIG. 31 shows a configuration in which the portion sandwiching the cholesteric layer 75 between the two λ / 4 plates 74 of FIG. 29 is inserted closer to the liquid crystal side than the CF layer, and is constructed as the same measure as in FIG.

FIG. 32 shows a structure in which the structure of FIG. 28 is combined with a phase difference compensating plate for improving the viewing angle. That is,
A phase difference compensating plate 56 is provided between the TFT substrate 51 and the TFT side polarizing plate 53, and a phase difference compensating plate 76 is provided between the CF substrate 71 and the λ / 4 plate 74.

FIG. 33 shows the brightness enhancement film 57 shown in FIG.
(Example: Sumitomo Chemical D-BEF, NIPOC manufactured by Nitto Denko
It is a combination of S). That is, the brightness enhancement film 57 is arranged outside the TFT side polarization plate 53.

FIG. 34 is a diagram in which the brightness enhancement film 57 is combined with FIG. That is, the TFT side polarizing plate 53
The brightness enhancement film 57 is arranged outside the.

FIG. 35 is a diagram in which the phase difference compensating plates 56 and 76 for improving the viewing angle are combined with FIG. That is, the phase difference compensating plate 56 is provided between the TFT substrate 51 and the TFT side polarizing plate 53, and the phase difference compensating plate 76 is provided between the CF substrate 71 and the λ / 4 plate 74.

FIG. 36 is a diagram in which the brightness enhancement film 57 is combined with FIG. That is, the TFT side polarizing plate 53
The brightness enhancement film 57 is arranged outside the.

FIG. 37 is a diagram in which the brightness enhancement film 57 is combined with FIG. That is, the TFT side polarizing plate 53
The brightness enhancement film 57 is arranged outside the.

The constitution of the liquid crystal cell of the present invention has the following effects.

(I) Even if it is used in the liquid crystal display devices of the display methods of the first to fourth embodiments, the brightness does not decrease.

(Ii) When a display with a large number of black screens is performed, the amount of reflected light is increased and the brightness is improved, and when a large number of white screens are displayed, the brightness is decreased. A display state similar to that of a CRT can be realized without using it.

Next, an embodiment of an optical birefringence compensation (OCB) type liquid crystal cell will be described.

FIG. 38 is an explanatory view of the structure of the OCB type liquid crystal cell used in the present invention, and FIG. 39 shows the relationship between the transmittance and the refractive index difference of the OCB liquid crystal cell.

One of the features of the first to fourth embodiments is that the voltage open side of the liquid crystal is used, so it is premised that a normally white (NW) type liquid crystal display device is used.

In this embodiment, the OCB has a fast response speed.
The liquid crystal cell will be described.

The OCB type liquid crystal cell uses a bend alignment mode, and the liquid crystal molecules 805 between the incident side polarization plate 530 and the emission side polarization plate 730 are applied when a voltage is applied.
As shown in FIG. 8 (a), the liquid crystal molecules 805 are aligned in parallel, and when no voltage is applied, as shown in FIG.
This is a system in which liquid crystal molecules are arranged in an arc by applying no voltage after applying a voltage.

In this system, as shown in FIG. 39, the transmittance change with respect to the refractive index change is different for each of red (hereinafter R), green (hereinafter G), and blue (hereinafter B), so that the R, G, B transmittances are different. Refractive index difference that increases monotonically 0 to 0.04 (gap 5.5 μm
In the case of), either the range is used, or the driving voltage is changed for each color, and the peaks of the respective colors are used to gain the luminance, either.

In this OCB type liquid crystal cell, the behavior of the liquid crystal is very unstable.
Bend deformation is maintained, but it will transform into splay or twist over time.

This is because the energy of bend deformation is higher than the energy of twist and spray on the low voltage side. However, since the bend deformation is maintained for a certain period of time, in the method of inserting the black display as in the first to fourth embodiments of the present invention, a voltage is applied each time, and the bend deformation does not collapse.

Next is the case of the embodiment of the horizontal electric field type liquid crystal cell.

FIG. 40 is a structural explanatory view of a horizontal electric field type liquid crystal cell used in the present invention. FIG. 41 is an operational explanatory view of the horizontal electric field type liquid crystal cell used in the present invention, and FIG. FIG. 43 is an explanatory diagram of a comb-teeth electrode and a liquid crystal alignment state when a liquid crystal having a positive dielectric constant is used in the method, and FIG. FIG. 44 shows an alignment state, and FIG. 44 shows a voltage-transmittance characteristic diagram of a horizontal electric field type liquid crystal cell used in the present invention.

The liquid crystal cell used in the present invention must be in a normally white mode. However, the lateral electric field method (IPS) can be used only in the normally black mode in the related art. This is because the lateral electric field type liquid crystal cell utilizes birefringence, and even if it is linearly polarized light in the initial state where no voltage is applied, it becomes elliptical or circularly polarized light when a voltage is applied and never becomes linearly polarized light. For this reason, even if the polarizing plates are arranged in parallel, black cannot be obtained, and only a display having a poor contrast and viewing angle can be obtained.

On the other hand, in this embodiment, as shown in FIG. 40, a retardation plate 760 is inserted between the exit side polarizing plate 730 and the liquid crystal cell 80. With such a configuration, as shown in FIG. 41, when no voltage is applied, the incident side polarization plate 53
The light passing through 0 and the liquid crystal cell is linearly polarized light 583, while the light passing through the retardation plate 760 is circularly polarized light 763.

When this light is passed through the emission side polarization plate 730, the light is emitted as linearly polarized light 733. On the other hand, when a voltage is applied to the liquid crystal cell, the light emitted from the liquid crystal cell becomes elliptically polarized light 584, and when it passes through the retardation plate 760, it becomes perpendicular to the transmission axis of the emission side polarization plate 730. There is a point where linearly polarized light 764 is obtained.

However, when this content is combined with a normal horizontal electric field type liquid crystal cell, there is only one point (voltage) at which black display can be obtained, which makes a liquid crystal cell which is very difficult to manufacture. Therefore, as shown in FIGS. 42 and 43, the voltage margin in the black state can be widened by defining the angle of the initial alignment between the comb-teeth electrode 85 and the liquid crystal molecules 805 that generate the lateral electric field when no voltage is applied. When a voltage is applied to the comb-teeth electrode 85 and the liquid crystal molecules 805 are perpendicular to the comb-teeth electrode 85 (when the liquid crystal has a positive dielectric constant) or parallel (when the liquid crystal has a negative dielectric constant). If black is displayed, the liquid crystal will not rotate more than vertically or in parallel. Therefore, the margin of black display is widened.

The orientation angle α shown in FIGS. 42 and 43,
An appropriate value of β changes depending on the wavelength of the retardation plate used, but a proportional relationship is established between the orientation angles α and β and the wavelength of the retardation plate as shown in equation (4).

Α (β) = Γ * (wavelength of retardation plate) (4) Γ: constant As a result, the voltage-transmittance characteristic as shown in FIG. It can be used for the display method of each embodiment of the present invention.

The following effects can be obtained in this embodiment.

(I) The NW type liquid crystal display device can be realized by the horizontal electric field method.

(Ii) The angle of initial orientation can be set arbitrarily by combining the wavelengths of the retardation film.

Next, an embodiment of the vertical alignment type liquid crystal cell will be described.

FIG. 45 is an explanatory view of the structure of a vertical alignment type liquid crystal cell used in the present invention, FIG. 46 is an image diagram when FIG. 45 is viewed in plan, and FIG. 47 is a refractive index and transmission of the vertical alignment type liquid crystal cell. The relationship of rates is shown.

In this vertical alignment type liquid crystal cell, FIG.
When no voltage is applied, the liquid crystal is vertically aligned with respect to the TFT substrate or the counter substrate (color filter etc.) so that the refractive index becomes almost 0 as shown in FIG. NW type by aligning the axes. When a voltage is applied as shown in FIG. 45 (a), it is 45 with respect to the transmission axis 735 of the input / output polarization plates 530 and 730.
The liquid crystal molecules 805 are controlled so as to tilt in a tilted direction.

The above states corresponding to FIGS. 45 (a) and 45 (b) are shown in plan views in FIGS. 46 (a) and 46 (b). However, even if black display is performed by such a method, the point at which the transmittance is minimized differs due to the difference in wavelength of each color as shown in FIG. Therefore, it is necessary to change the drive voltage for each color or change the gap.

As a result, the NW type liquid crystal display device can be realized by the vertical alignment method.

The present invention is also effective when an electric birefringence compensation (ECB) type liquid crystal cell other than the above-mentioned liquid crystal cell is adopted.

[0137]

According to the present invention, there is an advantage that a moving image display equivalent to that of a CRT can be obtained and there is no limitation on the method of forming the auxiliary capacitance of the liquid crystal cell.

Further, by eliminating the direct current component applied to the liquid crystal, a highly reliable liquid crystal display device can be obtained. Further, the same response speed can be obtained in any gradation display.

By performing the operation at double speed or more, a display in which flicker is not noticeable can be obtained, and
It is possible to change the ratio of the data screen and the black screen.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating Reference Example 1 of the present invention.

FIG. 2 is a polarity pattern diagram showing a polarity reversal method in Reference Example 1.

FIG. 3 is a waveform diagram illustrating drive waveforms of the drive method of FIG.

FIG. 4 is a waveform diagram illustrating drive waveforms of the drive method of FIG.

FIG. 5 is a characteristic conceptual diagram showing a response speed characteristic of liquid crystal with respect to a driving voltage.

6 is a block diagram showing a drive circuit module of Reference Example 1. FIG.

7 is a block diagram showing details of a data driver in FIG.

FIG. 8 is a block diagram showing an example of a drive circuit module according to a second reference example .

FIG. 9 is a block diagram showing another example of the drive circuit module according to the second reference example .

FIG. 10 is a signal waveform diagram illustrating an example of a driving concept of Reference Example 2.

FIG. 11 is a signal waveform diagram for explaining another example of the driving concept of the reference example 2.

FIG. 12 is a signal waveform diagram illustrating still another example of the driving concept of the reference example 2.

FIG. 13 is a circuit diagram illustrating an active element circuit combined with a reference example .

FIG. 14 is a schematic diagram illustrating Embodiment 1 of the present invention.

FIG. 15 is a block diagram illustrating a drive circuit module according to the first embodiment of the present invention.

16 is a block diagram showing details of the data driver of FIG.

Figure 17 is a waveform chart for explaining an example of drive timing of Embodiment Example 1.

FIG. 18 is a waveform diagram illustrating another example of the drive timing according to the first embodiment.

FIG. 19 is a waveform diagram illustrating still another example of the drive timing according to the first embodiment.

Figure 20 is a waveform chart illustrating another example of the drive timing of exemplary embodiment 1.

FIG. 21 is a schematic diagram illustrating Embodiment 2 of the present invention.

FIG. 22 is a polarity pattern diagram illustrating a polarity reversal method according to the second embodiment.

FIG. 23 is a schematic diagram illustrating Embodiment 3 of the present invention.

FIG. 24 is a polarity pattern diagram illustrating a polarity inversion method according to the third embodiment.

FIG. 25 is a schematic diagram illustrating Embodiment 4 of the present invention.

FIG. 26 is a polarity pattern diagram illustrating a polarity inversion method according to the fourth embodiment.

FIG. 27 is a schematic diagram illustrating a basic operation of a liquid crystal cell combined with the present invention.

FIG. 28 is a cross-sectional view showing a first configuration of a liquid crystal cell combined with the present invention.

FIG. 29 is a cross-sectional view showing the second configuration of the liquid crystal cell combined with the present invention.

FIG. 30 is a cross-sectional view showing the third configuration of the liquid crystal cell combined with the present invention.

FIG. 31 is a sectional view showing a fourth configuration of the liquid crystal cell combined with the present invention.

FIG. 32 is a sectional view showing a fifth configuration of a liquid crystal cell combined with the present invention.

FIG. 33 is a sectional view showing a sixth configuration of a liquid crystal cell combined with the present invention.

FIG. 34 is a sectional view showing a seventh configuration of a liquid crystal cell combined with the present invention.

FIG. 35 is a sectional view showing an eighth configuration of a liquid crystal cell combined with the present invention.

FIG. 36 is a cross-sectional view showing a ninth configuration of a liquid crystal cell combined with the present invention.

FIG. 37 is a cross-sectional view showing the tenth constitution of the liquid crystal cell combined with the present invention.

FIG. 38 is a sectional view showing the structure of an OCB type liquid crystal cell used in the present invention.

FIG. 39 is a characteristic diagram showing the relationship between the transmittance and the refractive index difference of an OCB liquid crystal cell.

FIG. 40 is a schematic diagram illustrating the configuration of a horizontal electric field type liquid crystal cell used in the present invention.

FIG. 41 is a schematic diagram illustrating the operation of a horizontal electric field type liquid crystal cell used in the present invention.

FIG. 42 is a schematic diagram illustrating a comb-teeth electrode and a liquid crystal alignment state when liquid crystal having a positive dielectric constant is used.

FIG. 43 is a schematic diagram illustrating a comb-teeth electrode and a liquid crystal alignment state when a liquid crystal having a negative dielectric constant is used.

FIG. 44 is a characteristic diagram showing the transmittance with respect to a driving voltage of a horizontal electric field type liquid crystal cell used in the present invention.

FIG. 45 is a schematic diagram illustrating the configuration of a vertical alignment type liquid crystal cell used in the present invention.

FIG. 46 is a plan view showing an image when FIG. 45 is viewed two-dimensionally.

47 is a characteristic diagram showing the relationship between the refractive index difference and the transmittance of the vertical alignment type liquid crystal cell of FIG. 45.

FIG. 48 is a schematic diagram illustrating a display system of a conventional liquid crystal display device.

FIG. 49 is a polarity pattern diagram illustrating a polarity inversion method of a conventional liquid crystal display device.

FIG. 50 is a waveform diagram illustrating a driving waveform according to a driving method of a conventional liquid crystal display device.

FIG. 51 is a block diagram showing a drive circuit module of a conventional liquid crystal display device.

[Explanation of symbols]

11,31 Data screen 22,42 black screen 51 TFT substrate 53 TFT side polarizing plate 530 Incident side polarizing plate 56 Phase difference compensator 57 Brightness enhancement film 60 LCD panel 61,611 Data driver 62, 621, 622 Scan line driving circuit 63, 631 control circuit 64 video signals 65 frame memory 67 Switching means 66 COM voltage generation circuit 71 CF substrate 73,730 CF side polarizing plate 74 λ / 4 plate 75 Cholesteric layer 76 Phase difference compensator 760 Phase plate 80, 90 Liquid crystal cell 85 Comb electrode 92 Drain wiring 95 Cgs 96 common electrode 900 TFT 805 liquid crystal molecule

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-44478 (JP, A) JP-A-2-157813 (JP, A) JP-A-5-303078 (JP, A) JP-A-11- 119189 (JP, A) JP-A-11-44891 (JP, A) JP-A-2-87881 (JP, A) JP-A-62-250776 (JP, A) JP-A-4-302289 (JP, A) JP-A-11-109921 (JP, A) JP-A-10-268849 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/133 505 G09G 3/36

Claims (18)

(57) [Claims] 1. A method of driving a liquid crystal display device, wherein a data screen and a black screen in each frame are vertically divided into two or more parts, and each is repeatedly displayed in each frame. . 2. The method of driving a liquid crystal display device according to claim 1 , wherein a black signal and a data signal are individually selected during a writing time of one scanning line, and a rising time of each scanning line is individually selected. And writing separate signals at the bottom of the screen. 3. The method of driving a liquid crystal display device according to claim 1 , wherein a black signal is output when the polarity of the data changes to improve the time constant of the data wiring. 4. The liquid crystal display device driving method according to claim 3 , wherein liquid crystal precharge is performed by overlapping a rising signal of a scanning line for writing a data signal with a black data portion. To do. 5. The black display and the data display are repeated for every three data lines (R, G, B) of three colors, and the portion for displaying the data screen and the black screen is shifted by three lines on the next screen. Driving method for liquid crystal display device. 6. A method of driving a liquid crystal display device, wherein black display and data display are performed every other pixel on a certain screen,
On the next screen, a method for driving a liquid crystal display device is characterized in that the pixels of the portion for displaying the data screen and the black screen are inverted. 7. The method for driving a liquid crystal display device according to claim 5, wherein the polarity inversion of the liquid crystal is 2n (n = n).
1, 2, 3 ...) Frame units and data line 2
The feature is that the polarity is reversed every other book. 8. The liquid crystal display device, comprising a means for dividing a data screen and a black screen in each frame into two or more parts vertically and repeatedly displaying each for each frame. 9. The liquid crystal display device according to claim 8 , further comprising means for controlling the scanning line driving circuit by dividing the scanning line driving circuit into two or more parts. 10. The liquid crystal display device according to claim 8 , wherein a data set circuit is provided at a stage subsequent to the latch circuit in the data driver, and a SET pulse is applied to the data driver so that a black screen can be displayed for an arbitrary time. Characterized by using a driver. 11. In a liquid crystal display device, black display and data display are repeated for every three data lines (R, G, B) of three colors, and in the next screen, three lines are provided for displaying the data screen and the black screen. A liquid crystal display device comprising means for shifting. 12. The liquid crystal display device has means for performing black display and data display every other pixel on a certain screen, and inverting the pixels of the data screen and the portion for displaying the black screen on the next screen. Liquid crystal display device. 13. Oite the liquid crystal display device according to claim 8, 11 or 12, when the black display state, characterized in that it comprises means which light is reused by being reflected to the liquid crystal cell . 14. The liquid crystal display device according to claim 13 , wherein the polarizing plate used is composed of a λ / 4 retardation plate and a reflective layer of cholesteric liquid crystal. 15. The liquid crystal display device according to claim 13 , wherein a retardation compensating plate or a brightness enhancement film for expanding a viewing angle or a combination thereof is used as a means for reflecting and reusing the light. Is characterized by. 16. The liquid crystal display device according to claim 8, 11 or 12 , wherein the liquid crystal display mode to be combined is a normally white mode. 17. The liquid crystal display device according to claim 16 , wherein the normally white mode liquid crystal cell is a twisted nematic liquid crystal cell, a horizontal electric field mode liquid crystal cell,
Vertical alignment type liquid crystal cell, optical birefringence compensation type liquid crystal cell,
Alternatively, it is characterized by being either an electric birefringence compensation type liquid crystal cell. 18. A method of driving an active matrix type liquid crystal display device, wherein the liquid crystal display mode is a normally white mode, and the liquid crystal display device is arranged such that a black screen frame is inserted between each frame of the data display screen. A method of driving a liquid crystal display device, characterized in that the liquid crystal display device is driven by an applied drive voltage.