JP2001042282A - Liquid crystal display device and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress image distortion and afterimage caused by coexistence of fast and slow parts in response speed, by providing this device with a means for alternately and repeatedly displaying a data picture and a black picture. SOLUTION: A data picture and a black picture are alternately repeatedly displayed in every frame. For example, the display screen is driven so that a data picture 11 is driven in a 1st frame, a black picture 22 in 2nd frame, a data picture 31 in a 3rd frame, a black picture 42 in a 4th frame, and so on. In such a manner, the response speed becomes constant irrespective of picture, and the picture is stabilized and a display without feeling of afterimage is obtained. Further, in the driving method therefor, the polarity of the driving voltage to be applied to the liquid crystal is reversed in every two frames, namely, every two pictures (data picture and black picture), and further, it is also possible to display at a speed two time as fast as a normal frame frequency (50 Hz-80 Hz) or faster by arranging frame memory on the side of a driving circuit module.

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

[0002]

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

A display method of a conventional liquid crystal display device using such a drive circuit is a method of sequentially switching 60 screens when the frame frequency is 60 Hz as shown in FIG. That is, in the first frame, the first display screen 1
1, the second display screen 21 is driven in the second frame, 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.
And the polarity pattern 1 of the third display screens 11 and 31
11 and 311 are the same, and the pattern has the opposite polarity to the second and fourth display screens 210 and 410. Paying attention to 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. This is realized by applying a voltage to the data electrode of the liquid crystal display panel.

[0005]

The conventional liquid crystal display device employs a system in which the screens are sequentially switched as shown in FIG. 48. One screen has a frame frequency of 60 Hz for 1/60 second. Holding that screen.

[0006] Here, if the next screen comes, the human eye will recognize both screens with the previous screen, and there is a disadvantage that a feeling of afterimage is generated. This afterimage feeling cannot be eliminated even if the response speed of the liquid crystal is improved.

In addition, in the operation of the liquid crystal, the direction in which the voltage is applied is proportional to the reciprocal of the applied voltage value. Therefore, when all gradations exist on one screen as in a natural image, the image is distorted. There is a disadvantage that it becomes.

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 a white screen is displayed continuously, the bend deformation is broken. There is a drawback that disturbance of the image occurs.

[0009]

According to the present invention, there is provided a liquid crystal display device characterized by improving the display of moving images by alternately repeating a data screen and a black screen, and a method of driving the same.

Further, the data screen and the black screen are set to 1
There is provided a means for displaying every other frame and repeating the data screen and the black screen at twice or more the normal speed.

It is also characterized in that a frame memory is provided as a means for repeating the screen at the double speed or higher, and a means for applying a common electrode potential in a retrace interval between frames for displaying the black screen.

Further, it is characterized in that an auxiliary capacitance is formed on the scanning line.

In a method for driving a liquid crystal display device,
A method of driving a liquid crystal display device, characterized in that a data screen and a black screen in each frame are vertically divided into two or more divisions and each is repeatedly displayed for each frame. This driving method is characterized in that a black signal and a data signal are individually selected for a rising time of each scanning line within a writing time of one scanning line, so that different signals are written to an upper portion and a lower portion of the screen.

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, precharging of the liquid crystal is performed by overlapping a rising signal of a scanning line for writing a data signal with a black data portion.

Further, according to the present invention, in the liquid crystal display device and the method of driving the same, black display and data display are performed every other scanning line, and in the next screen, a portion for displaying the data screen and the black screen is one line. A liquid crystal display device characterized by shifting and a driving method thereof are also obtained.

In the above-mentioned method of driving a liquid crystal display device, the polarity of the liquid crystal is inverted in units of 2n (n = 1, 2, 3,...) Frames.

Further, black display and data display are repeated for every three data lines (R, G, B) of three colors, and in the next screen, the portion for displaying the data screen and the black screen are shifted by three lines. And a method of driving the same.

Further, in the liquid crystal display device and the method of driving the same, black display and data display are performed every other pixel on a certain screen, and the pixels on the data screen and the black screen display portion are inverted on the next screen. A characteristic liquid crystal display device and a driving method thereof can also be obtained.

In the above method of driving a 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

Further, the liquid crystal display device is characterized in that the data screen and the black screen in each frame are divided into two or more upper and lower parts, and each of the means is repeatedly displayed for each frame. Can be In this liquid crystal display device, it is also characterized in that the scanning line driving circuit is divided into two or more parts and each is controlled. Further, this liquid crystal display device is characterized in that a data driver is used which can provide a black screen at an arbitrary time by providing a data setting circuit after a latch circuit in the data driver and applying a SET pulse.

In the above-mentioned liquid crystal display device, 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 phase difference plate and a reflection layer made of cholesteric liquid crystal.

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

Further, in these liquid crystal display devices, a liquid crystal display device characterized in that a liquid crystal display mode to be combined is a normally white mode is obtained. The mode liquid crystal cells are twisted nematic liquid crystal cells, horizontal electric field liquid crystal cells, vertical alignment liquid crystal cells,
It is also characterized in that it is either an optically birefringent compensation type liquid crystal cell or an electric birefringence compensation type liquid crystal cell.

[0024]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) The present invention is characterized in that a display screen is repeated for a data screen and a black screen for each frame 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, and the black screen 42 in the fourth frame
It drives as follows.

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 drive circuit module side, display can be performed at twice or more the normal frame frequency (50 Hz to 80 Hz).

FIG. 6 is a block diagram of a driving circuit according to the present invention. The difference from the conventional basic drive circuit (FIG. 51) is that a video signal 64 is taken into a control circuit 63, its output is controlled, and supplied to a data driver 61 via a switching means 67. FIG. 7 shows the details of the data driver 61. This driver is a conventionally used driver.

As shown in FIG. 6, the drive module of the present invention stores information for one screen in the frame memory 65, reads out the information at about twice the speed, and displays the write data screen on the liquid crystal panel 60. Next, the control circuit 63 writes all 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 changed to the conventional frame frequency 60
At 30 Hz, flicker may occur since 30 data screens and 30 black screens are repeated respectively.
Therefore, flicker can be suppressed by providing the frame memory 65 in the module and setting the frame frequency to about twice.

When the frame polarity reversal, which is the polarity reversal of a normal liquid crystal panel, is used for the display method of the present invention, when the data screen is of a positive polarity, all the black screens have a negative polarity and always have a negative polarity.
DC component is applied to the liquid crystal with a polarity of (a + -polarity DC component is generated when the data screen is-).

Therefore, as shown in FIG. 2, the DC component can be canceled by inverting the polarity for each pair of the data screen and the black screen.

In FIG. 2A, the polarity patterns 111 and 221 of the data screen 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 polarity patterns 310 and 420 at 42 have the opposite polarities to the first and second frames. In FIG. 2B, the first
The polarity 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 polarity screen 220 and 310 of the data screen 31 of the third frame are opposite to the polarities of the first and fourth frames.

FIGS. 3 and 4 show changes in drive voltage when attention is paid to the polarity of the pattern surrounded by the thick line on the upper left of FIGS. 2 (a) and 2 (b). When the data screen is + with respect to the common potential Vc, the next black screen is +
By setting the polarity of the next data screen and the black screen to-, the DC component can be canceled in four screens.

This polarity is 4 as shown in FIGS.
It suffices that the data screen set and the black screen set in the screen have both + and-polarities. In this case, the polarity inversion is performed every two screens. However, if the polarity inversion is performed every 2n (n = 1, 2, 3,...) Frames, the DC component is canceled when the 4n screen is completed.
The invention is not limited to two-frame inversion.

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

Further, as shown in FIG. 5, the response speed of the conventional liquid crystal is 1 / in the direction in which a voltage is applied to the liquid crystal (0V → XV).
(Drive voltage) and the direction in which the voltage is released (X
V → 0V) hardly depends on the drive voltage. This corresponds to the following formulas (1) and (2), which are basic formulas for the liquid crystal response speed.

Τon (voltage application side) = (γ * d * d) / (εo * εa (V * V−Vc * Vc)) (1) τoff (voltage open side) = (γ * d * d) / (Π * π * K) (2) where γ: viscosity of liquid crystal d: gap of liquid crystal cell εo: vacuum dielectric constant εa: difference in dielectric constant 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 high response speed and a portion having a low response speed are mixed, and the image is perceived by the human eye as a distortion afterimage.

In the present invention, by inserting the black screen between the data screens, only the open voltage side described above is used, so that the response speed is constant irrespective of the screen, and the screen is stable and a display without a feeling of afterimage is obtained. Can be Therefore, in the present invention, a moving image can be displayed without using a liquid crystal mode having a particularly fast response speed.

By performing the display method of the present invention, 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 configuration of the storage capacitor of the liquid crystal cell. (C) A highly reliable liquid crystal display device can be obtained by eliminating the DC component applied to the liquid crystal. (D) The same response speed can be obtained in any gradation display. (E) By performing the operation at double speed or higher, it is possible to obtain a display in which the flicker is inconspicuous. (F) The ratio between the data screen and the black screen can be changed.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described.

FIGS. 8 and 9 show a second embodiment of the present invention.
As shown in the block diagram of the drive circuit module of
The common electrode (COM not shown) of the liquid crystal display panel 60 is not shown.
The circuit configuration is such that the COM voltage generation 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 embodiment. The display method in the present embodiment is to alternately display a data screen and a black screen as in the first embodiment. In the first embodiment, data written in the frame memory is written at about twice the speed.
As shown in FIG. 3, this is performed using a gate storage type liquid crystal panel in which an auxiliary capacitance (hereinafter referred to as Csc) 93 is formed on the gate wiring electrode 91. In the figure, 92 is a drain wiring, 90 is a liquid crystal cell, 95 is a parasitic capacitance Cgs between gate and source, 96 is a common electrode, and 900 is a TFT.

In this embodiment, the driving is realized by any of the configurations shown in the drive 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 such that the signal of the common electrode (hereinafter referred to as COM electrode) is out of the display section (return section in CRT) as shown in FIGS. ), The black screen is inserted between the data screens by shaking at the voltage V1 shown in the following equation (3).

V1 = ((CLC + Csc) / Csc) × Vcr (3) V1: amplitude of common electrode signal Vcr: amplitude of black signal of liquid crystal cell CLC: liquid crystal capacity (during black display) Csc: auxiliary capacity (gate storage) Shaking the COM electrode with the amplitude of V1 makes it possible to write a charge to the liquid crystal cell capacitor CLC through Csc connected to the virtually grounded gate electrode.

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

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

In this embodiment, the COM electrode is set to T
It cannot be applied to a common (COMMON) storage method in which an auxiliary capacitance is provided between the pixel electrode and the pixel electrode through the insulating film provided on the FT substrate side.

In the second embodiment, in addition to the effect of the first embodiment, an effect is obtained that a frame memory can be omitted as a liquid crystal display device as shown in FIG.

Third Embodiment Next, a third embodiment of the present invention will be described.

FIG. 14 is an explanatory diagram of Embodiment 3 of the present invention, FIG. 15 is a block diagram of a module of Embodiment 3 of the present invention,
FIG. 16 is a block diagram of a data driver used in the third embodiment, and FIGS. 17 to 20 show driving timing explanatory diagrams of the third embodiment.

In this embodiment, as shown in FIG. 14, the display screen in each frame is divided into two or more upper and lower parts, and a data screen and a black screen are repeated for each unit. That is, in the n frame, if the upper half is a data screen nD and the lower half is a black screen nB, (n +
1) In a frame, the upper half is a black screen (n + 1) B and the lower half is a 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 timing diagrams 17 and 18. Here, OE1 and OE2 in FIG. 15 are output enable, SP1 and SP2 are start pulses, C
LK is a clock signal, O1 and O2 are liquid crystal panels 60
And second scanning line driving circuits 6 for driving the scanning lines
The outputs DO1 and DO1 of the data drivers 21 and 622 indicate 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, each of which 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 SET pulse is low (hereinafter L), all the outputs are set to L and the black screen voltage is output, and when the SET pulse is high (H), the data stored in the latch is output. It is a driver that outputs a data screen. Using this driver, the output waveform of DO1 in the timing diagrams of FIGS. 17 to 20 is realized.

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 scan line drive circuit 621 is controlled by OE1, SP1 and CLK so that only the data portion is written to the upper scan line output O1, and the lower scan line output O2 is written to the OE2, OE2, and 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 between 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 is used.
Is raised every two CLKs, a black signal of the same polarity can be written to the liquid crystal.

According to this method, even a short-time black signal can be written into the liquid crystal, so that the time of the data signal portion can be lengthened.

FIG. 18 shows a black signal written in the upper part.
FIG. 11 is a diagram showing the timing of writing a data signal in the lower part.

In the above description, the case where the black signal is output after the data signal with the same polarity of the data signal and the black signal has been described. Separately from this, the timing when the black signal is raised before the data signal is shown in FIGS.
In this case, since the polarity is the same as that of the data, an effect equivalent to that of the precharge can be obtained.

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

It is necessary to confirm that the time for performing the precharge does not affect the data display. (If the precharge is performed too much, the luminance in white display may be reduced.)

Further, as shown by the waveform of DO1 in FIG. 19, since the overshoot occurs once, there is an advantage that the black signal is output when the polarity of the data changes, thereby improving the time constant of the data wiring. .

FIG. 20 is a diagram for explaining the operation timing of writing the black signal to the liquid crystal by the upper scanning line driving circuit 621 and writing the data signal by the lower scanning line driving circuit 622.
In this case, the scanning line signal output for writing the black signal writes the same polarity every two scanning lines, and the contents are the same as those described with reference to FIGS.

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

(I) No frame memory is required.

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

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

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

Embodiment 4 Next, Embodiment 4 of the present invention will be described.

FIG. 21 is a diagram illustrating a display method according to the fourth embodiment of the present invention. FIG. 22 shows a polarity inversion method according to the present embodiment.

In this embodiment, in a certain display screen n, every other scanning line, for example, an odd-numbered scanning line is set to data display nD, and an even-numbered scanning line is set to black display nB, and the next display screen (n + 1) In the above, 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 the first embodiment is obtained. Also in this embodiment, as shown in FIG. 22, 2n (n = 1, 2, 3,.
-) By inverting the polarity for each screen, it is possible to drive the liquid crystal without applying DC. In the illustrated example, the polarity patterns 131 and 241 of the display screens 13 and 24 in the first and second frames are the same, and the polarity patterns 330 and 440 of the display screens 33 and 44 in the third and fourth frames are inverted. .

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

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

(Ii) There is no need to have a frame memory.

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

(Iv) The design of the liquid crystal panel (particularly, the writing characteristic to the liquid crystal) can be made by the same design as the conventional one.

(Embodiment 5) Embodiment 5 of the present invention will be described below.

FIG. 23 is an explanatory diagram of a display method according to the fifth embodiment of the present invention. FIG. 24 shows a polarity inversion method according to 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 every three data lines (n + 1) on the next display screen (n + 1). (n + 1) B and data display (n + 1) D are continuously arranged. By repeating this display, a moving image display equivalent to that of the first embodiment 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 means that the data line is
If the polarity is inverted every other line, the polarity depends on either + or-when attention is paid in the scanning line direction, and the common electrode line or gate line to which Csc is connected is DC-directed in a biased direction. Would. As a result, asymmetry occurs in the voltage applied to the liquid crystal, causing display defects such as flicker and crosstalk. Therefore, the DC component is canceled every two data lines, and 2n (n = 1, 2, 2)
3.) The liquid crystal can be driven without applying a direct current to the liquid crystal by simultaneously inverting the polarity for each screen.

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 inverted. are doing.

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

(I) There is no need to have a frame memory.

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

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

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described.

FIG. 25 is an explanatory diagram of a display method according to the sixth embodiment of the present invention. FIG. 26 shows a polarity inversion method according to the present embodiment.

In the present embodiment, on a certain display screen n, a data display nD and a black display nB are displayed every third data line 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, and a so-called checkerboard pattern is exhibited. In the next display screen (n + 1), the data display of the previous screen and the black display are inverted and displayed. That is, black display (n + 1) B and data display (n +
1) D is displayed, and data display (n + 1) D and black display (n + 1) are provided for every third data line with respect to even-numbered scanning lines.
B is displayed.

In the above example, the display is changed every three data lines, because it is assumed that the display is made to correspond to three color data signals. If the display is changed every other data line, a checkerboard display in which data display and black display are repeated for each pixel can be realized.

As described above, a moving image display equivalent to that of the first embodiment can be obtained by the display method of the sixth embodiment.

In the sixth embodiment, as described in the fifth embodiment, as shown in FIG. 25, 2n (n = 1,
2, 3,...) It is necessary to invert the polarity every other screen and simultaneously invert the polarity of every other data line. Thus, 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 is displayed.
And 28 have the same polarity patterns 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 has the following effects as compared with the first embodiment.

(I) There is no need to have a frame memory.

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

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

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

FIG. 27 is a diagram illustrating the basic operation of a liquid crystal cell to which the driving methods of the first to sixth embodiments are applied, and FIGS.
FIG. 7 shows a configuration 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 of Nos. 1 to 6 are intended to obtain a moving image display comparable to that of a CRT. However, in any of the embodiments, since a black screen is inserted between data screens, the screen brightness may be reduced. Although this method can be realized by a conventional liquid crystal cell configuration, it is desirable to combine the liquid crystal cell of the present invention described below in order to compensate for this reduction in screen luminance.

The 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 the polarization state is unchanged in the black display state when the liquid crystal cell 80 is a black display state. Pass through. Here, at the time when the light passes through the liquid crystal cell 80, λ / 4 is tilted by about 45 degrees from the polarization state of the light.
When the optical film 74 that generates the phase difference is inserted, right circularly polarized light (or left circularly polarized light) indicated by reference numeral 741 in a white display state, and left circularly polarized light (or right circularly polarized light) indicated by reference numeral 742 in a black display state. Become.

By providing a cholesteric liquid crystal layer 75 capable of selectively reflecting left circularly polarized light (or right circularly polarized light) after the light converted to circularly polarized light, light is reflected in a black display state, and this reflection is performed. The light thus obtained is further converted into linearly polarized light through the λ / 4 phase difference plate, and returns to the inside of the liquid crystal cell and eventually to the backlight (B / L) light source, so that it can be reused. In the white state, light passes through the cholesteric layer with its polarization 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. A well-known RGB color filter is formed on the inner surface of the CF substrate 71. Then, the TFT substrate 51 is disposed with the liquid crystal layer 80 interposed therebetween, and a polarizing plate 53 is formed outside 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 denotes a liquid crystal molecule.

FIG. 29 shows that a cholesteric layer 75 is sandwiched between two λ / 4 plates 74 and a polarizing plate 7 is further placed thereon.
3 is provided. In the case of FIG. 29, the circularly polarized light that has passed through the cholesteric layer 75 in white display is further converted to a λ / 4 plate 74.
By converting the light into linearly polarized light through the polarizing plate 73, black display is improved and the viewing angle and 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 the light once passed through the CF layer is reflected and made incident on the CF layer again, there is a possibility that the luminance may be reduced and the light recycling efficiency may be reduced. Countermeasures are taken by providing it before the incidence.

FIG. 31 shows a cholesteric layer 75 sandwiched between the two λ / 4 plates 74 of FIG. 29 inserted between the CF layer and the liquid crystal side, and is configured as a countermeasure similar to FIG.

FIG. 32 shows a configuration in which the configuration of FIG. 28 is combined with a phase difference compensator 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 is a view showing a state in which the brightness enhancement film 57 is added to FIG.
(Example: Sumitomo Chemical D-BEF, NIPOC manufactured by Nitto Denko
S). That is, the configuration is such that the brightness enhancement film 57 is arranged outside the TFT-side polarizing plate 53.

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

FIG. 35 is a view in which the phase difference compensating plates 56 and 76 for improving the viewing angle are combined with FIG. 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. 36 is a view in which a brightness enhancement film 57 is combined with FIG. That is, the TFT-side polarizing plate 53
And a brightness enhancement film 57 is arranged outside.

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

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

(I) The brightness does not decrease even when used in the liquid crystal display devices of the display systems of the first to sixth embodiments.

(Ii) When a display with a large number of black screens is performed, the amount of reflected light increases to increase the luminance, and when there are a large number of white screens, the luminance decreases. Therefore, B / L luminance adjustment, drive circuit correction, and the like are performed. Without this, a display state similar to that of a CRT can be realized.

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 refractive index difference and the transmittance of the OCB liquid crystal cell.

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

In this embodiment, the OCB having a fast response speed
The formula 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 polarizing plate 530 and the outgoing-side polarizing plate 730 are applied to the liquid crystal cell shown in FIG.
8A, the liquid crystal molecules 805 are aligned in parallel, and when no voltage is applied, as shown in FIG.
In this method, liquid crystal molecules are arranged in an arc by applying a voltage and then applying no voltage.

In this method, as shown in FIG. 39, the transmittance changes with respect to the refractive index change for each of red (R), green (G), and blue (B). Monotonically increasing refractive index difference 0 to 0.04 (gap 5.5 μm
) Or the method of changing the drive voltage for each color and using up to the peak of each color to increase the luminance.

In this OCB type liquid crystal cell, the behavior of the liquid crystal is very unstable, and when no voltage is applied, a certain period of time is obtained as shown in FIG.
Bend deformation, but over time it will splay or twist.

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

The following is a case of the embodiment of the in-plane switching mode liquid crystal cell.

FIG. 40 is an explanatory view of the structure of the in-plane switching mode liquid crystal cell used in the present invention. FIG. 41 is an explanatory view of the operation of the in-plane switching mode liquid crystal cell used in the present invention. FIG. 43 is an explanatory view 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 is an explanatory diagram of the alignment state, and FIG. 44 is a voltage-transmittance characteristic diagram of the liquid crystal cell of the in-plane switching mode used in the present invention.

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

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

When this light passes through the output side polarizing plate 730, the light is output 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 this passes through the phase difference plate 760, it becomes perpendicular to the transmission axis of the emission side polarizing 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 is obtained, and a liquid crystal cell which is extremely difficult to manufacture is produced. Therefore, as shown in FIG. 42 and FIG. 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 for generating a horizontal electric field when no voltage is applied. When a voltage is applied to the comb electrode 85 and the liquid crystal molecules 805 become perpendicular to the comb electrode 85 (when the dielectric constant of the liquid crystal is positive) or parallel (when the dielectric constant of the liquid crystal is negative). If black is displayed, the liquid crystal will not rotate vertically or more than parallel. Therefore, the margin for black display is widened.

The orientation angles α, shown in FIG. 42 and FIG.
The 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 by the equation (4).

Α (β) = Γ * (wavelength of retardation plate) (4) 定 数: constant As a result, a voltage-transmittance characteristic as shown in FIG. 44 is obtained even in the in-plane switching method, so that an NW-type liquid crystal display device can be obtained. It can be used for the display method of each embodiment of the present invention.

In the present embodiment, the following effects can be obtained.

(I) It is possible to realize an NW type liquid crystal display device by a horizontal electric field method.

(Ii) The angle of the initial alignment can be arbitrarily set by the combination of the wavelengths of the retardation plates.

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

FIG. 45 is an explanatory view of the structure of the 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 the refractive index and transmission of the vertical alignment type liquid crystal cell. The relationship between the rates is shown.

In this vertical alignment type liquid crystal cell, FIG.
As shown in (2), when no voltage is applied, the liquid crystal is vertically aligned with respect to the TFT substrate or the counter substrate (such as a color filter) so that the refractive index becomes almost 0, and the transmission of the incident side polarizing plate 530 and the exit side polarizing plate 730 is performed. The NW type is obtained by aligning the axes. As shown in FIG. 45 (a), when a voltage is applied, the transmission axis 735 of the input / output polarizing plates 530 and 730 is set at 45 °.
The liquid crystal molecules 805 are controlled so as to fall in the inclined direction.

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

As a result, there is an effect that the NW type liquid crystal display device can be realized by the vertical alignment method.

The present invention is effective even if, for example, an electric birefringence compensation (ECB) type liquid crystal cell is employed other than the liquid crystal cell described above.

[0137]

According to the present invention, there are advantages that a moving image display equivalent to that of a CRT can be obtained, and that the method of forming the auxiliary capacitance of the liquid crystal cell is not restricted.

In addition, by eliminating the DC 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 operating at twice or more the speed, it is possible to obtain a display in which flicker is inconspicuous.
It is possible to change the ratio between the data screen and the black screen.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a first embodiment of the present invention.

FIG. 2 is a polarity pattern diagram showing a polarity inversion method according to the first embodiment.

FIG. 3 is a waveform chart for explaining a driving waveform of the driving method in FIG.

FIG. 4 is a waveform chart for explaining a driving waveform of the driving method of FIG. 2 (b).

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

FIG. 6 is a block diagram showing a driving circuit module according to the first embodiment.

FIG. 7 is a block diagram showing details of a data driver in FIG. 6;

FIG. 8 is a block diagram illustrating an example of a drive circuit module according to Embodiment 2.

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

FIG. 10 is a signal waveform diagram illustrating an example of a driving concept according to the second embodiment.

FIG. 11 is a signal waveform diagram illustrating another example of the driving concept of the second embodiment.

FIG. 12 is a signal waveform chart for explaining still another example of the driving concept according to the second embodiment.

FIG. 13 is a circuit diagram illustrating an active element circuit combined with the embodiment.

FIG. 14 is a schematic diagram illustrating Embodiment 3 of the present invention.

FIG. 15 is a block diagram illustrating a drive circuit module according to Embodiment 3 of the present invention.

FIG. 16 is a block diagram showing details of a data driver shown in FIG. 16;

FIG. 17 is a waveform chart illustrating an example of drive timing according to the third embodiment.

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

FIG. 19 is a waveform chart for explaining still another example of the drive timing according to the third embodiment.

FIG. 20 is a waveform chart illustrating another example of the drive timing according to the third embodiment.

FIG. 21 is a schematic view illustrating Embodiment 4 of the present invention.

FIG. 22 is a polarity pattern diagram illustrating a polarity inversion method according to the fourth embodiment.

FIG. 23 is a schematic diagram illustrating Embodiment 5 of the present invention.

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

FIG. 25 is a schematic diagram illustrating Embodiment 6 of the present invention.

FIG. 26 is a polarity pattern diagram illustrating a polarity inversion method according to the sixth 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 sectional view showing a first configuration of a liquid crystal cell combined with the present invention.

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

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

FIG. 31 is a cross-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 the liquid crystal cell combined with the present invention.

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

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

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

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

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

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

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

FIG. 40 is a schematic view illustrating the configuration of a liquid crystal cell of an in-plane switching mode used in the present invention.

FIG. 41 is a schematic view for explaining the operation of a liquid crystal cell of an in-plane switching mode used in the present invention.

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

FIG. 43 is a schematic diagram illustrating a comb-tooth 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 a transmittance of a liquid crystal cell of a horizontal electric field type used in the present invention with respect to a driving voltage.

FIG. 45 is a schematic view 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.

FIG. 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 method 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 conventional driving method of a liquid crystal display device.

FIG. 51 is a block diagram showing a driving 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 Liquid crystal panel 61, 611 Data driver 62, 621, 622 Scanning line drive circuit 63 , 631 control circuit 64 video signal 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 difference plate 80,90 liquid crystal cell 85 Comb electrode 92 Drain wiring 95 Cgs 96 Common electrode 900 TFT 805 Liquid crystal molecule

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H093 NA16 NA33 NA43 NA64 NC26 NC29 NC35 ND10 ND35 ND60 NE06 NF04 NF05 NF09 NF13 NH15 5C006 AA01 AA16 AC28 AF03 AF04 AF44 AF46 AF73 AF83 BB14 BB16 BB29 BF02 BF03 BF03 FA04 5C080 AA10 BB05 DD06 EE19 FF11 GG08 JJ02 JJ04 JJ05 JJ06

Claims (30)

[Claims] 1. A liquid crystal display device comprising: means for alternately and repeatedly displaying a data screen and a black screen. 2. The liquid crystal display device according to claim 1, wherein the data screen and the black screen are displayed every other frame, and the data screen and the black screen are repeated at twice or more normal speed. It is characterized by having means. 3. The liquid crystal display device according to claim 2,
A frame memory is provided as means for repeating the screen at the double speed or higher. 4. The liquid crystal display device according to claim 1, further comprising means for oscillating a common electrode potential in a retrace interval between frames for displaying the black screen. 5. The liquid crystal display device according to claim 4,
A storage capacitor is formed on a scanning line. 6. A method for driving a liquid crystal display device, wherein a data screen and a black screen are alternately repeated. 7. The method for driving a liquid crystal display device according to claim 6, wherein the data screen and the black screen are displayed every other frame, and the data screen and the black screen are displayed at twice or more normal speed. And is repeated. 8. The driving method of a liquid crystal display device according to claim 6, wherein the display of the black screen is realized by applying a common electrode potential in a retrace interval between frames. 9. A method for driving a liquid crystal display device, comprising: dividing a data screen and a black screen in each frame into two or more parts vertically and repeatedly displaying each of the frames for each frame. . 10. The method of driving a liquid crystal display device according to claim 9, wherein a black signal and a data signal are individually selected for a rising time of each scanning line within a writing time of one scanning line, so that the upper part of the screen is selected. And writing different signals at the bottom of the screen. 11. The driving method of a liquid crystal display device according to claim 9, wherein a black signal is output when the polarity of data changes to improve the time constant of the data wiring. 12. The method for driving a liquid crystal display device according to claim 11, wherein a rising signal of a scanning line for writing a data signal is overlapped with a black data portion to precharge the liquid crystal. I do. 13. A driving method for a liquid crystal display device, wherein black display and data display are performed every other scanning line, and a portion for displaying the data screen and the black screen is shifted by one line in the next screen. A method for driving a display device. 14. The method of driving a liquid crystal display device according to claim 6, wherein the polarity of the liquid crystal is inverted by 2n.
(N = 1, 2, 3,...) Is characterized in that it is performed in frame units. 15. The method according to claim 1, wherein black display and data display are repeated every three color data lines (R, G, B), and a portion for displaying the data screen and the black screen is shifted by three lines in the next screen. For driving a liquid crystal display device. 16. A driving method of a liquid crystal display device, wherein black display and data display are performed every other pixel on a certain screen, and pixels of a part for displaying the data screen and the black screen are inverted on the next screen. For driving a liquid crystal display device. 17. The method for driving a liquid crystal display device according to claim 15, wherein the polarity of the liquid crystal is inverted by 2n.
(N = 1, 2, 3,...) It is characterized in that the polarity is inverted for every two data lines on a frame basis. 18. A liquid crystal display device, comprising: means for dividing a data screen and a black screen in each frame into two or more divisions vertically and repeatedly displaying each of them for each frame. 19. The liquid crystal display device according to claim 18, further comprising means for dividing the scanning line driving circuit into two or more divided sections and controlling each of them. 20. The liquid crystal display device according to claim 18, 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 set the data to a black screen at an arbitrary time. It is characterized by using a driver. 21. A liquid crystal display device comprising: means for performing black display and data display for every other scanning line, and for shifting the portion for displaying the data screen and the black screen by one line in the next screen. Display device. 22. In the liquid crystal display device, black display and data display are repeated every three data lines (R, G, B) of three colors, and in the next screen, a data screen and a black screen are displayed in three lines. A liquid crystal display device having a shifting means. 23. A liquid crystal display device comprising: means for performing black display and data display every other pixel on a certain screen, and inverting pixels of a portion for displaying the data screen and the black screen on the next screen. Liquid crystal display device. 24. The liquid crystal display device according to claim 1, wherein the liquid crystal cell includes means for reflecting and reusing light in a black display state. Features. 25. The liquid crystal display device according to claim 24, wherein the polarizing plate used is composed of a λ / 4 retardation plate and a reflection layer made of cholesteric liquid crystal. 26. The liquid crystal display device according to claim 24, wherein the light is reflected and reused by using a phase difference compensator or a brightness enhancement film for expanding a viewing angle or a combination thereof. It is characterized by. 27. The liquid crystal display device according to claim 1, 18, 21, 22, or 23, wherein a liquid crystal display mode to be combined is a normally white mode. 28. The liquid crystal display device according to claim 27, wherein the normally white mode liquid crystal cell is a twisted nematic liquid crystal cell, a horizontal electric field type liquid crystal cell,
Vertical alignment type liquid crystal cell, optical birefringence compensation type liquid crystal cell,
Alternatively, it is any one of an electric birefringence compensation type liquid crystal cell. 29. A driving method for an active matrix type liquid crystal display device, wherein the liquid crystal display mode is a normally white mode, and the driving is performed such that a black table frame is inserted between each frame of the data display screen. A method for driving a liquid crystal display device. 30. A driving method of an active matrix type liquid crystal display device, wherein a liquid crystal display mode is a normally white mode, and a data display area and a black display area are evenly distributed in each image frame. A driving method for a liquid crystal display device, wherein the driving is performed so that a region and a black display region are spatially exchanged.