JPH0850278A - Ferroelectric liquid crystal display device and its driving method in assigning intensity levels - Google Patents

Abstract

PURPOSE:To diminish a driving voltage width and to improve the controllability of a display state of pixels. CONSTITUTION:This liquid crystal display device consists of so-called pixel divisions formed by interposing ferroelectric liquid crystals into the intersected parts of scanning electrodes and signal electrodes to constitute pixels and constituting one pixel by plural pieces of the partial pixels provided with plural pieces of the scanning electrodes constituting the one pixel. The liquid crystal display device is mainly constituted in the following manner: Pixel dividing means are so constituted as to make display in order of A B C at all times by setting the ratio of the line widths of the plural (>=3 pieces) scanning electrodes A:B:C constituting the one pixel to 1:NP-1:1 (N, P are both an integer of >=2); further, the means for assigning intensity levels by pixel division are so constituted as to control switching of the ferroelectric liquid crystals by simultaneously and independently impressing respectively different selection voltages independently and directly to the plural scanning electrodes and impressing respectively different voltages to the partial pixels composed of these scanning electrodes and one piece of the signal electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pixel-divided ferroelectric liquid crystal display device, and more particularly to a gradation display method using the device.

[0002]

2. Description of the Related Art As a method for displaying gray scales in a liquid crystal display device using a ferroelectric liquid crystal, for example, Japanese Patent Laid-Open No. HEI 2
-96118, one pixel is composed of a plurality of scanning electrodes and a plurality of signal electrodes to form one pixel from a plurality of partial pixels, and each partial pixel is independently driven. Therefore, there is a method by pixel division in which gradation display within one pixel is performed. According to this means, FIG.
As shown in FIG. 3, the centers of the divided pixels do not move, and careless pairing with adjacent pixels can be prevented. In the figure, the symbols (1) to (16) are the display gradation numbers shown in the lighting / non-lighting pattern diagram of each pixel.

In such a pixel-divided ferroelectric liquid crystal display device, a driving circuit is provided for each scanning line which constitutes a partial pixel, and is driven while sequentially scanning the scanning electrodes which constitute one pixel. . In this case, the time required to rewrite one pixel becomes longer as the number of scan electrodes increases. For example, if the pixel is not divided,
The time required for the latter is doubled when compared with the case of being composed of one scanning line.

On the other hand, in the method disclosed in Japanese Patent Laid-Open No. 3-189622, in which a plurality of scan electrodes are connected to one drive circuit via different resistors in order to reduce the number of drive circuits, A plurality of scan electrodes are selected at the same time, which results in an increase in the number of scan electrodes, which solves the problem that the time required to rewrite one pixel becomes long. This method is considered as a kind of transmission line of ITO electrode, and the phase of the input waveform is delayed as the resistance of the transmission line is larger, so even a partial pixel which constitutes one pixel is connected to the driver through a low resistance scanning. The applied voltage waveform is different between the partial pixel on the electrode and the partial pixel on the scanning electrode connected to the driver via a high resistance. Depending on the voltage waveform applied to the signal electrode, both partial pixels are rewritten. That is, only one partial pixel can be rewritten, or both partial pixels can be rewritten.

However, since the resistivity of the ITO electrode is quite high, even in the partial pixel on the scanning electrode connected to the driver through the low resistance, the phase is considerably delayed in the partial pixel at the end. Even if the phase of the partial pixel at the input end of the scan electrode connected to the driver via the resistance higher than the voltage waveform applied to this partial pixel at the end is not delayed, uniform gray scale display can be obtained in the panel. Therefore, the phase of the partial pixel at the end of the scan electrode connected to the driver via this high resistance will be further delayed. For this reason, in such a method, it is necessary to perform scanning so that display can be performed even with the partial pixel having the most delayed phase, and thus an extra scanning time is required as compared with the case of displaying black and white two gradations. Will end up.

Further, as a method of time-divisionally displaying 2 ^K gradation display using pixels capable of only binary display, there is a method disclosed in Japanese Patent Laid-Open No. 64-61180. In this method, all the scan electrodes constituting the liquid crystal display device are divided into a plurality of sets, and each set of scan electrodes is scanned K times in one frame period. For example, in the case of displaying 2 ³ gradations, all the scanning electrodes are divided into two sets, the data of bit1 is displayed in the first set as shown in (1) and (2) of FIG. 14, and then the first set of data is displayed. To the group of
The data of t2 is displayed, the data of bit2 is displayed in the second set, the data of bit3 is displayed in the first set, and the b is displayed in the second set.
The data of it1 is displayed, the data of bit3 is displayed in the second set, and 8 gradations are displayed.

[0007]

SUMMARY OF THE INVENTION A first object of the present invention is to provide a pixel division method which prevents inadvertent pairing with an adjacent pixel regardless of the method disclosed in Japanese Patent Laid-Open No. 2-96118. Is. A second object of the present invention is to provide a method for enabling gradation display by pixel division in the same scanning time as in the case of displaying black and white two gradations.
In particular, it is an object of the present invention to provide a method of making a driving voltage width as small as possible and further improving controllability of a display state of a pixel when a plurality of partial pixels are collectively driven in a liquid crystal display device having divided pixels. Furthermore, a third object of the present invention is to provide a method for performing the time division gradation display method according to Japanese Patent Laid-Open No. 64-61180 using pixels capable of gradation display.

[0008]

The present invention has been made to achieve the above objects, and the first one of the gist thereof is a ferroelectric liquid crystal at the intersection of the scanning electrode and the signal electrode. A liquid crystal display device in which a pixel is formed by interposing a plurality of scanning electrodes that form one pixel, and one pixel is formed by a plurality of partial pixels, and the pixel is formed. The line width ratio of the plurality of scanning electrodes is 1: N ^P −
A ferroelectric liquid crystal display device is characterized in that it is 1: 1 (N and P are both integers of 2 or more).

A second aspect of the invention is that a pixel is formed by interposing a ferroelectric liquid crystal at the intersection of the scanning electrode and the signal electrode, and a plurality of scanning electrodes forming one pixel are provided.
A liquid crystal display device in which one pixel is composed of a plurality of partial pixels, wherein different voltages are simultaneously and independently applied to a plurality of scan electrodes forming the one pixel. On the device.

Further, the third gist is that a pixel is formed by interposing a ferroelectric liquid crystal at the intersection of the scanning electrode and the signal electrode, and a plurality of scanning electrodes forming one pixel are provided. Is a liquid crystal display device in which one pixel is configured by the partial pixels, and the line width ratio of a plurality of scanning electrodes configuring the one pixel is 1: N ^P -1: 1 (N and P are both 2 In the ferroelectric liquid crystal display device having the above integer), a ferroelectric liquid crystal having a negative dielectric anisotropy is used, and a plurality of scan electrodes forming one pixel have different waveforms for each scan electrode. Voltage is simultaneously applied to the signal electrode corresponding to the scanning electrode, the voltage waveform applied to the corresponding partial pixel becomes a continuous pulse waveform of the same polarity when the display state of the partial pixel is changed, Reverse polarity when the display state of partial pixels is not changed In the method for driving gradation display of a polar dielectric liquid crystal display device, a voltage is applied so as to form a continuous pulse waveform.

As a fourth aspect, a pixel is formed by interposing a ferroelectric liquid crystal at the intersection of the scanning electrode and the signal electrode, and a plurality of scanning electrodes forming one pixel are provided. A ferroelectric liquid crystal display device in which one pixel is composed of a plurality of partial pixels, and different voltages are independently and simultaneously applied to a plurality of scanning electrodes forming the one pixel. A liquid crystal having a negative dielectric anisotropy is used, and a voltage having a different waveform is simultaneously applied to a plurality of scan electrodes constituting one pixel, and the signal electrodes corresponding to the scan electrodes are applied to the scan electrodes. , The voltage waveform applied to the corresponding partial pixel has a continuous pulse waveform of the same polarity when the display state of the partial pixel is changed, and the continuous pulse waveform of opposite polarity when the display state of the partial pixel is not changed Becomes In ferroelectric gradation display driving method of a liquid crystal display device and applying the cormorants voltage.

In the third and fourth aspects, when the product of the time component of the voltage waveform applied to the partial pixel and the voltage is the same for all voltage waveforms, the DC component does not remain in the liquid crystal. Therefore, it is preferable since it does not deteriorate the characteristics of the liquid crystal. Further, in all of the above ferroelectric liquid crystal display devices and their gradation display driving methods, a liquid crystal display device capable of displaying M gradations is used, and all the scan electrodes constituting the liquid crystal display device are (1 + M). If the scan electrode set is divided into scan electrode groups of ½ or less, one scan electrode set is scanned, then that scan electrode set is continuously scanned, and then another scan electrode set is scanned, the time division is performed at higher speed. Since gradation display is possible,
preferable. This is a fifth embodiment which will be described later.

The present invention is configured as described above in order to achieve the above-mentioned various purposes. The configuration common to the present invention is that the ferroelectric liquid crystal is provided at the intersection of the scanning electrode and the signal electrode. And a plurality of scanning electrodes that form one pixel are provided to form one pixel.
This is a liquid crystal display device by so-called pixel division in which one pixel is configured.

To achieve the first object, in the present invention, the line width ratio of a plurality (three or more) of scan electrodes A: B: C forming one pixel is set to 1: N ^P -1: 1. (N and P are both integers of 2 or more) and are always displayed in the order of A → B → C. In order to achieve the second object, in the present invention, means for directly and simultaneously applying different selection voltages to a plurality of scan electrodes independently is provided, and a partial pixel composed of those scan electrodes and one signal electrode is provided. Different voltages can be applied,
Controls the switching of ferroelectric liquid crystals. In this case, it is preferable to use a ferroelectric liquid crystal having negative ferroelectric anisotropy.

And, a more preferable constitution of the present invention is as follows.
Voltages having different waveforms are simultaneously applied to a plurality of scan electrodes forming one pixel, and the scan electrodes to which the voltage is applied and a signal pixel electrode are used. Corresponding to the signal electrodes so that continuous pulse waveforms of the same polarity that change the display state are applied to the same number of partial pixels and continuous pulse waveforms of the opposite polarity that do not change the display state are applied to the remaining partial pixels. Apply voltage. The voltage waveform applied to the above-mentioned partial pixel has various different waveforms in each partial pixel according to the display state of the pixel, but the product of the time component of the voltage waveform and the voltage should be the same for all voltage waveforms. Is preferred.

Further, in order to achieve the third object, the present invention uses a liquid crystal display device capable of displaying M gray scales on one pixel by the above method and the like, and uses all the scanning electrodes constituting the device. (1 + M) / 2 is divided into the following set of scan electrodes, is a set of scan electrodes is scanned during the time t = 0 to T _0, continue the set time t = T ₀ of the scanning electrodes ～2T ₀ Scan between
After that, another scan electrode set is similarly scanned, and the scan electrode set is again scanned during the time period MT ₀ + T _{0 to} MT ₀ + 2T ₀ .

[0017]

According to the first aspect of the invention, the line width ratio of the plurality of (three or more) scan electrodes A: B: C forming one pixel is 1 :.
If N ^P -1: 1 (N and P are both integers of 2 or more), and if they are always displayed in the order of A → B → C as shown in FIG. 9 described later, then 0, 1, N ^P , and N ^P +1 four states can be displayed, and the display center of the pixel a _ij is only moves from the scanning electrodes L _iA to the center of gravity of the pixel a _ij. As a result, the display center moves the same in all pixels, and careless pairing with adjacent pixels can be prevented.

According to the second invention, different voltages can be simultaneously applied independently to a plurality of scan electrodes forming one pixel, so that each of the partial pixels composed of those scan electrodes and one signal electrode is individually applied. Different voltages can be applied, the ferroelectric liquid crystals forming each partial pixel can be switched separately, and gradation display is possible.

According to the third and fourth aspects of the invention, the ferroelectric liquid crystal molecule has a spontaneous polarization P _S perpendicular to the long axis direction of the molecule and an electric field E generated from the potential difference between the scanning electrode and the signal electrode. And a force F proportional to the square of the electric field E and the difference .DELTA..epsilon. In the dielectric constant between the long axis direction and the short axis direction of the molecule. That is, a force F expressed by F = K ₀ × P _S × E + K ₁ × Δε × E ² acts on the ferroelectric liquid crystal molecule having a negative dielectric anisotropy Δε, and F is given at a specific electric field E _min. It becomes maximum and F becomes small on both sides. The memory pulse width required for the liquid crystal molecules to be rewritten from one stable state to the other stable state takes a minimum memory pulse width τ _min at the electric field E _min , and a larger memory pulse width at an electric field larger than this. Become.

When a ferroelectric liquid crystal material having a negative dielectric anisotropy is used, the above-mentioned force acts on the liquid crystal molecules constituting the pixel according to the voltage applied to the pixel, and the liquid crystal molecule has a specific electric field. It will have a minimum memory pulse width tau _min relative to E _min.

Further, when a voltage having a continuous pulse waveform of the same polarity is applied to the pixel, the memory pulse width and the minimum memory pulse with respect to the voltage applied by the subsequent pulse are affected by the effect of the first pulse as compared with the case of a single pulse. Width τ
_min becomes smaller, and the voltage E _min that gives the minimum memory pulse width becomes larger. On the other hand, when the voltage of the continuous pulse waveform with the opposite polarity is applied, the memory pulse width and the minimum memory pulse width τ _min for the voltage applied by the subsequent pulse become larger than the case of the single pulse, and the minimum memory pulse The electric field E _min that gives the width becomes smaller.
The polarity of the subsequent pulse is in the direction in which the molecule moves to another stable state.

FIG. 1 is a diagram for explaining the relationship between the voltage value and the memory pulse width for the pulse following the first pulse in the case of the same polarity and the opposite polarity. As shown in this figure, τ _min and E _min change as described above due to the influence of the first pulse, so that when a pulse of the same polarity is applied, the memory state of the ferroelectric liquid crystal can be changed. When a pulse of opposite polarity is applied, the memory state of the ferroelectric liquid crystal cannot be changed. In this case, both DC components can be made equal, so that even when the same voltage waveform is applied to the signal electrode, the potential difference between the scan electrode and a scan electrode to which a certain selection voltage is applied has the same polarity. The potential difference between the scanning electrodes to which the selection voltage is applied has the opposite polarity,
Each partial pixel is simultaneously driven to a predetermined display state, and gradation display is performed.

Further, by setting the product of the time component and the voltage to be the same for all the voltage waveforms, it becomes easy to balance the direct current with respect to the liquid crystal molecules constituting the pixel. As will be understood from the above, the voltage of the pulse following the first pulse is preferably larger than the voltage value corresponding to E _min in the case of the opposite polarity, and further, the voltage of the following pulse has the same polarity. It is more preferable that the voltage value is smaller than the voltage value corresponding to E _min in the case of.

Further, in the present invention, the fifth described later.
As an embodiment of the present invention, M
A liquid crystal display device capable of gradation display is divided into scan electrode groups of (1 + M) / 2 or less for all scan electrodes constituting the liquid crystal display device, and a scan electrode group is subjected to time t = 0. ~
Scanning is performed during T ₀ to display state a, then the scan electrode set is scanned during time t = T _{0 to} 2T ₀ to display state b, and then another scan electrode set is similarly scanned. Again, the set of scan electrodes can be scanned during the time period MT ₀ + T _{0 to} MT ₀ + 2T ₀ . In this way, in the same manner as the method disclosed in Japanese Patent Laid-Open No. 64-61180, the state between the first displayed state a and the next displayed state b is 1: M.
It is possible to display M ^M gradations from 0 to ^MM −1 by using a liquid crystal display device capable of displaying ^M gradations.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic cross-sectional structure of a liquid crystal display device 1 common to the present invention is as shown in FIG. 2, in which two glass substrates 5a,
5b are arranged to face each other, and one glass substrate 5
On the surface of a, a plurality of transparent signal electrodes S made of indium tin oxide (hereinafter abbreviated as ITO) or the like are arranged in parallel with each other, and a transparent insulating film 6a made of SiO ₂ or the like is coated thereon. Has been done.

On the surface of the other glass substrate 5b facing the signal electrode S, a plurality of transparent scanning electrodes L made of ITO or the like are arranged in parallel to each other in a direction orthogonal to the signal electrode S, and on top of that. Is covered with a transparent insulating film 6b made of SiO ₂ or the like. Transparent alignment films 7a and 7b made of polyvinyl alcohol or the like that have been subjected to a rubbing treatment are formed on the insulating films 6a and 6b, respectively. The two glass substrates 5a and 5b are bonded together with a sealant 8 leaving an injection port in part, and the alignment films 7a and 7b are injected from the injection port.
After the FLC 9 is introduced into the space sandwiched by b by vacuum injection or the like, the injection port is sealed with the sealant 8.

The two glass substrates 5a and 5b thus bonded together are sandwiched by two polarizing plates 10a and 10b arranged so that their polarization axes are orthogonal to each other. The distance between the scanning electrode L and the signal electrode S is about 1.5 μm.

FIG. 3 is a plan view showing an electrode structure of a pixel used in the second and fourth embodiments of the present invention. There are three scan electrodes L forming one pixel, and the scan electrodes L _iA , L _iB ,
It is composed of L _iC and has one signal electrode S. A scan side drive circuit is connected to the scan electrode L via output terminals DL _iA , DL _iB , and DL _iC , and a signal side drive circuit is connected to the signal electrode S via an output terminal Si.

In this example, as FLC9, SCE-8 manufactured by Merck & Co. and a compound represented by the following structural formula [1] were used:
Using the liquid crystal composition blended in the ratio of 1, the alignment film 7
PSI-A-2101 manufactured by Chisso Corporation was used as a and 7b.

[0030]

Embedded image

The dielectric anisotropy of this FLC 9 is negative, and this device has two stable states, the first and second stable states.

Using this liquid crystal display device, gradation display driving was performed by the following method. First, the scan electrode scans by applying a selection voltage and a non-selection voltage to each set of three scan electrodes forming one pixel. For example, 3 of L _0A , L _0B and L _0C
A set of L _0A , L _0B , and L _0C is selected by applying a selection voltage to the books at the same time and a non-selection voltage to the remaining scanning lines, and then selecting L _1A , L _1B , and L _1C . A selection voltage is applied to three lines at the same time, and a non-selection voltage is applied to the remaining scanning lines in order.

FIG. 4 shows the relationship between the switching pulse width and the continuous pulse composed of two pulses having the same pulse width in the apparatus of this embodiment. The horizontal axis represents the voltage value aV ₀ of the first half pulse.
And the vertical axis represents the pulse width t ₀ of the latter half pulse. The voltage value of the second half pulse is 40V minus the voltage value aV ₀ of the first half pulse (40-aV ₀ ), and in the figure (O), 90% of the FLC molecules constituting the liquid crystal device are switched. (X) indicates the pulse width with which 10% of the area is switched. It can be seen that both pulse widths start to change significantly from the vicinity where the same polarity changes to the opposite polarity.

Based on this data, the pulse width of both the first half pulse and the second half pulse is 80 μs as shown below.
The voltage waveform at point A in FIG. 4 is applied to the liquid crystal to be switched, and the liquid crystal not to be switched is shown in FIG.
The voltage waveform at point B is applied.

FIG. 5 is a diagram showing voltage waveforms of the selection voltage, the non-selection voltage, the signal voltage, and the voltage applied to the pixel, which are used in this embodiment and are determined in this way. In the figure, a ₀ V ₀ = V _e −V ₄ = V _c −V ₃ = V _a −V ₂ = 0.8 v 40 −a ₀ V ₀ = V _f + V ₄ = V _d + V ₃ = V _b + V ₂ = 39.
_{2v a 1 V 0 = V e} -V 3 = V c -V 2 = V a -V 1 = -3.2v 40-a 1 V 0 = V f + V 3 = V d + V 2 = V b + V 1 = 43.
And 2v, and a _{V 1 = V 2 + 4v =} V 3 + 8v = V 4 + 12v V a = V c + 4v = V e + 8v V f = V d + 4v = V b + 8v V e = V 4 + 0.8v.

The voltages V _f and V ₁ can be arbitrarily determined, but in this embodiment V _f = V ₁ = 25.6 v. Therefore, V _d = V _{2
= 21.6v, V b = V 3} = 17.6v, V 4 = 13.6
v, V _e = 14.4 v, V _c = 18.4 v, V _a = 22.
It becomes 4v. In this case, the pulse voltage in the first half is aV ₀ (-
1 <a <1), the pulse voltage of the latter half is set to (1-a) V ₀ , and the pulse widths are made the same, so that the direct current balance of the molecules in the pixel can be easily achieved.

Using these voltage signals, different selection voltages V _CA , V _CA , are applied to the three scan electrodes L _0A , L _0B and L _0C .
V _CB and V _CC were applied simultaneously, and the non-selection voltage V _CD was applied to the other scan electrodes. When V _SE is applied to the signal electrode S ₁ , all three partial pixels are rewritten to the first stable state, and when V _SF is applied, A _01A and A _01B are rewritten to the first stable state, and V _SG When A is applied, A _01A is rewritten to the first stable state, and when V _SH is applied, none of the partial pixels are rewritten, whereby four gradation driving is performed.

Such driving is possible because, when a ferroelectric liquid crystal having a negative dielectric anisotropy is used, the following behavior occurs when the memory pulse width of the ferroelectric liquid crystal molecule is two consecutive pulses. This is because That is, in the case of the same polarity pulse, the larger the absolute value of the voltage in the first half is, the larger E _min is with respect to the voltage in the latter half, and the smaller τ _min is. In the case of the reverse polarity pulse, the larger the absolute value of the voltage in the first half is, This is because E _min with respect to the voltage decreases and τ _min increases. In the above, the polarity of the voltage in the latter half is premised on the direction that the molecule moves to the other stable state (first stable state). In the opposite case, the molecule changes its stable state in both the same polarity and the opposite polarity. Absent.

The method of taking each voltage may be other than the value in this embodiment, for example, V _a > V _c > V _e > 0 V _a + V _b = V _c + V _d = V _e + V _f V _a −V _{3 = V c -V 4 V c} -V 3 = V e -V 4 V a -V 2 = V c -V 3 V c -V 2 = V e -V 3 V a -V 1 = V c -V _{2 V c -V 1 = V e} -V 2 V 4 <V 3 <V 2 < may be to satisfy the relation between V _1.

In this case, for example, the pulse width t ₀ = 80 μs
And _{then, a 0 V 0 = V e} -V 4 = 0v (1-a 0) V 0 = V f + V 4 = 40v-a 0 V 0 a 1 V 0 = V e -V 3 ≦ -4v (1- a ₁₎ as _{V 0 = V f + V 3} = 40v-a 1 V 0, is driven as well. This is an embodiment of the fourth invention of the present application.

By the way, at the voltages (9) to (20) in FIG. 5, the FLC molecules constituting the pixel are rewritten from the second stable state to the first stable state, or the stable state is maintained. However, since the FLC molecules constituting the pixel cannot be rewritten from the first stable state to the second stable state, the following two methods were used.

The first method is to scan electrodes L _iA , L _iC and L _iC.
Before applying the selection voltages V _CA , V _CB , and V _CC of (1) to (3) in FIG. 5 to the other scan electrodes L _KA , L _KB , and L _KC (k ≠
To i), the selection voltages V _CA , V _CB , and V of (1) to (3) in FIG.
Since there is a period during which the application of _CC, during that period, the scan voltage _{L iA, L iB, -V h} <V 4 becomes a voltage -V _h in FIG. 6 (25) to L _iC, subsequently -V _r < This is a method of applying a voltage −V _{r of} V ₁ . In this case, no matter which voltage (5) to (8) in FIG. 5 is applied to the signal electrode S _J , the pixels on the scan electrodes L _iA , L _iB , and L _iC are shown in FIG.
The voltages of the same polarity are applied as in (26) to (29), and the stable state of the FLC molecules forming the pixels on the scan electrodes L _iA , L _iB , and L _iC is rewritten to one stable state.

[0043] Since the DC component of the voltage applied to the FLC molecules must be canceled, the mutual _{V h + V r = V a} + V b = V c + V d = V e + V f is preferred. In the present embodiment -V _h = -10v,
It was -V _r = -30v. In addition, other scan electrodes L
_{1 (1 ≠ k, 1 ≠} i) to the pulse width t ₀ of _{V g = (V 2 + V} 3) / 2 becomes following the voltage V _g voltage of the pulse width t ₀ as (4) in FIG. 5 If −V _g is applied, the FLC that constitutes the pixel A _IJ on the scan electrode
The stable state of the molecule does not change. In this embodiment, V _g = 1
It was set to 9.6v.

The second method is to determine which scan electrodes L _KA , L _KB ,
Selection voltage also to the L _KC of Fig. 5 (1) ~ (3) V CA, V CB,
A time for which V _CC is not applied is provided, and the scan electrode L _iA is set for that time.
Following voltage -V _a pulse width t ₀ in FIG. 7 (1) by applying a voltage -V _b of the pulse width t ₀ to, 5 to the scanning electrodes L _iB
Following the voltage -V _c of the pulse width t ₀ (2) by applying a voltage -V _d of the pulse width t _0, the voltage -V _e of the pulse width t ₀ in FIG. 5 (3) to the scanning electrodes L _iC This is a method of subsequently applying a voltage −V _f having a pulse width t ₀ .

At this time, the signal electrode S _J for rewriting the stable state of the FLC molecule forming the pixel A _ij to the other stable state is pulsed following the voltage −V ₄ having the pulse width t ₀ in FIG. 7 (5). A voltage V ₄ having a width t ₀ is applied to the partial pixels A _ijA ,
_Voltages (7), (9), and (11) in FIG. 7 which are potential differences between the scanning electrodes and the signal electrodes are applied to A _ijB and A _ijC , and the pixel A
The stable state of the FLC molecule forming _ij is rewritten to the other stable state. The pulse width t ₀ shown in FIG. 7 (6) is applied to the signal electrode S _J which holds the stable state of the FLC molecules forming the pixel A _ij .
Voltage -V Following ₁ by applying a voltage V ₁ of the pulse width t _0, the pixel A _ijA, A _ijB, in FIG. 7 is a potential difference between the scanning electrodes and signal electrodes to A _IJC (8), (10) , (12) are applied to maintain the stable state of the FLC molecules forming the pixel A _ij . The scan electrodes L _K not selected are shown in FIG.
(4) a voltage V _g of the pulse width t ₀ is applied subsequent to the voltage -V _g pulse width t ₀ of, constituting pixels A _KJ on the scanning electrodes are the non-selection voltage V _CD is applied L _K The stable state of the FLC molecule is maintained regardless of the voltage applied to the signal electrode S _J.

In the present embodiment, the selection voltage V _CB of FIG. 5 (2) applied to the scanning electrode L _iB is directly supplied from the scanning side drive circuit, but the selection voltage V _CB of FIG. 5 (2) is Figure 5
Since the voltage is an intermediate voltage between the selection voltage V _CA of (1) and the selection voltage V _CC of FIG. 5C, the scan electrode L _iB is capacitively coupled to the scan electrode L _iA and the scan electrode L _iC , and the scan electrodes at both ends. There is also a method of indirectly supplying a voltage to the scanning side driving L _iB by directly supplying a voltage to the scanning side driving circuit to L _iA and L _iC . In this case, if the coupling capacitance is large, the coupling impedance is small, and the voltage waveform applied to the scan electrode L _iB is not distorted so much, so that uniform gray scale display can be obtained in the panel.

When a ferroelectric liquid crystal having a positive dielectric anisotropy is used, the memory pulse width decreases monotonously with the voltage applied to the pixel. It is also possible to apply a selection voltage to a plurality of scanning electrodes at the same time as in the present invention using such a liquid crystal to perform gradation display.

In this case, the voltage waveform shown in FIG. 8 is used instead of the voltage waveform shown in FIG. 5 of the previous embodiment. Each voltage of 8 _{V a + V 1> V a} + V 2> V a + V 3> V a + V 4 V c + V 1 = V b + V 2 = V a + V 3 V c + V 2 = V b + V 3 = V and _a + V _4, by applying a voltage V _c + V ₁ of the pulse width t ₀ Following voltage -V _c -V ₁ pulse width t ₀ to the pixel, the stable state of the FLC molecules constituting the pixel one stable Although rewritten from the state to the other stable state, the voltage V _c + V pulse width t ₀ Following voltage -V _c -V ₂ of the pulse width t ₀ to the pixel
_{Even if 2} is applied, it is necessary that the stable state of the FLC molecule forming the pixel cannot be rewritten from one stable state to the other stable state. However, in such a liquid crystal, the potential difference between the voltage V _c + V ₁ and the voltage V _c + V ₂ is larger than the potential difference between the voltage V _e −V ₄ and the voltage V _e −V _{3 in} the above-described embodiment, and driving is possible. A large voltage width is required, and if the voltage width is reduced, there are drawbacks such as increased malfunctions, but this is feasible. This is an embodiment of the second invention of the present application.

In the above embodiment, one signal electrode forming one pixel is used, but a plurality of signal electrodes may be used, and the number of scanning electrodes may be two or four or more. Therefore, the signal electrodes S _jA and S _jB have two lines with a line width ratio of 2: 1 and the line width ratio of the three scanning electrodes L _iA , L _iB and L _iC is 1: 2 ² −1: 1 is the example of the mode shown in FIG. FIGS. 12 (a) to 12 (d) are examples showing the electrode configuration of the first invention of the present application. As shown in FIG. 9, in this display method, the three partial pixels on the same signal electrode are necessarily inverted from the dark display state to the bright display state in the order of the scanning electrodes L _iA → L _iB → L _iC , and each signal electrode Four gradation display of 0, 1, 2 ² , 2 ² +1 can be performed for each.

In this case, all the FLC molecules forming the partial pixels of the pixel A _ij are set in one stable state in advance, and then the three scan electrodes L _iA , L _iB , and L _iC forming the pixel A _ij are formed. The selection voltages V _CA , V _CB and V _CC of (1) to (3) are applied. At this time, if the voltages V _SE , V _SF , V _SC , and V _SH of (5) to (8) in FIG. 5 are _applied to the signal electrode S _jA , the signal electrode S _j
0, 1, using the pixels A _ijAB , A _ijBB , and A _ijCB on _JB
4,5 can be represented is four gradations of the voltage V _SE of FIG. 5 to the signal electrodes _{S jB (5) ~ (8} ), V SF, V SG, by applying a V _SH, on signal electrodes S _jA It can be similarly represented four gradations of 0,2,8,10 the case of using the fractional pixel having 8 area ratio: pixels _a ijAA, a ijBA, 2 with _a ijCA.

If these two 4-gradation displays are combined,
As shown in FIG. 9, the pixels A _ijAB , A _ijBB , and A on the signal electrode S _jB are
pixels A _IjAA on _ijCB and signal electrodes _{S jA,} A ijBA, 16 gradations using A _IjCA becomes possible display. Similarly, the signal electrodes S _jA , S _jB and S _jC have three line width ratios of 3: 1: 1, and the three scan electrodes L _iA , L _iB and L _{iC have} a line width ratio of 1. : 3 ² -1: 1 is the example of the embodiment of FIG. 12 (b). Also in this case, as in FIG. 9, three partial pixels on the same signal electrode are necessarily inverted from the dark display state to the bright display state in the order of the scanning electrodes L _iA → L _iB → L _iC , and 0 for each signal electrode. 4 gradation display of 1, 3 ² , 3 ² +1 is possible.

Further, the signal electrodes S _jA , S _jB and S _jC are _set to 4:
The number of scan lines L _iA , L _iB , and L _iC is 3 with a line width ratio of 2: 1.
In FIG. 12C, the line width ratio of the three scan electrodes is set to 1: 2 ³ -1: 1. Also in this case, as in FIG. 9, the three partial pixels on the same signal electrode must be the scanning electrodes L.
_iA → L _iB → L _iC sequentially with inverted from a dark display state to a bright display state of each signal electrode 0,1,2 ^3, 2 ³ +1 4
Gradation display is possible.

Looking at the above embodiments, it seems that the present invention is limited to the case where the number of scanning electrodes forming one pixel is three, but the signal electrodes S _jA and S _jB are _arranged in a 2: 1 line. With a width ratio of two, the scan electrodes L _iA , L _iB , L _iC , L _iD , L _iE ,
The line width ratio of the seven scanning electrodes L _iF and L _iG is 1: 2 ² −1:
1: 2 ³ − (2 ² +1): 1: 2 ² −1: 1 in FIG.
The example of the mode (d) is also an example showing the electrode configuration of the first invention of the present application.

As described above, in the electrode configuration of the first invention of the present application, the line width ratio of the three scanning electrodes L _iA , L _iB , and L _iC among the plurality of scanning electrodes forming one pixel is 1: M. ^P- 1: 1
(M and P are both integers of 2 or more). Further, the case of applying the drive waveform of FIG. 5 to the scan electrodes divided in this way is the embodiment of the third invention of the present application.

If the liquid crystal display device is already capable of displaying 16 gradations by the method shown in FIG. 9, all the scanning electrodes constituting the liquid crystal display device are (1 + M) / 2 = 17/2 ≧ 8 sets of scan electrode sets, and a certain scan electrode set is divided by time t
= ₀ to T ₀ , followed by scanning that set of scan electrodes during time t = T _{0 to} 2T ₀ , then another set of scan electrodes in the same manner, and again that scan electrode. Time for 17T
If scanning is carried out between _{0 and} 18T ₀ , it is disclosed in JP-A-64-61180.
No. The method of publication can be applied to M gradations displayable liquid crystal display device, a 0-16 ¹⁶ -1 to 16 ¹⁶ gradations can be displayed.

[0056] That is, all of the scanning electrodes constituting the FLC panel is divided into eight blocks from G ₀ ~G ₇ as shown in FIG. 10, scans between blocks G ₀ time 0 to T ₀ (Fig. 1
0 In expresses put oblique solid line in the frame of the time 0 to T ₀ of block G ₀ for scanning are) scans between blocks G ₀ time T ₀ ～2T _0, during the time 2T ₀ ～3T ₀ scanning the blocks G _1, scanning between blocks G ₁ time 3T ₀ ~4T _0, ...
..., scanning the block G ₇ during time 14T _{0 to} 15T ₀ ,
Scans between block G ₇ time 15T ₀ ~16T _0, time 16T ₀ between ～17T ₀ Which block is also not scanning, scans between blocks G ₀ again time 17T ₀ ~18T _0, ...
If so, the ratio of the time from the first scan to the next scan for each block and the time from the next scan to the second scan can be set to 1:16, and the time of 1:16 Pixels can be lit in width.

Since the amount of transmitted light is the area of the pixel × lighting time,
If one pixel can be used to light an area from 0 to 15 as shown in FIG. 9, the pixel is time-divisionally scanned as shown in FIG. 10 so that partial pixels forming the pixel are scanned from the first scan. The area illuminated at T ₀ time until the next scan,
The lighting area can be set separately for 16T ₀ hours from the next scan to the next scanning, and ₀ can be set by the area x lighting time.
Up to 255 gradations can be displayed. This is the fifth embodiment of the present invention.

By the way, the information signal normally output to the display of a personal computer or the like is a sequential scanning signal, but the information signal output to the display of a television or the like is an interlaced scanning signal. If an interlaced scanning signal is input as it is to a display with memory such as FLCD,
The data of the odd-numbered field is displayed even in the even-numbered field, and when a moving image is displayed, an afterimage or the like occurs.

[0059] Therefore, the scanning electrodes L _2n is an even field in TFT or the like, L _{2n + 1} writes data of the scanning electrodes L _2n to the scanning electrodes L _{2n + 1} is an odd field, L _{2n + 2} to the scanning electrodes L _{2n +} Methods such as writing the data of ₁ have been proposed. Although it is possible to scan in the same manner in this embodiment,
In the even field (expresses put oblique solid line in the frame of the time 0 to T ₀ in FIG. 10 block G _0.) Scanning electrodes L _{2n + 1} while erasing as shown in Figure 11 scanning electrodes L _2n There is also a method of writing and writing L _{2n + 1} while erasing the scan electrode L _2n in the odd field.

That is, the odd-numbered scan electrodes G _{0 to} G ₇ forming the FLC panel are divided into 8 blocks, and the even-numbered scan electrodes G _{8 to} G _F are divided into 8 blocks. While scanning the block G ₀ from ₀ to T _0, the block G ₈ is erased at the same time (in FIG. 11, a diagonal broken line is shown in the frame of the time ₀ to T ₀ of the block G ₈ ). scans between blocks G ₀ of T ₀ ~2T _0, time 2T ₀ to 3
While scanning the block G ₁ during T _0, the block G ₁ is simultaneously scanned.
Clear _9, scans between blocks G ₁ time 3T ₀ ~4T _0, ......, while scanning between block G ₇ time 14T ₀ ~15T _0, erase the block G _F simultaneously, time 15T ₀
Scans between block G ₇ of ~16T _0, time 16T ₀ to 1
No block is scanned during 7T ₀ , and time is 17T ₀ to 1
While scanning between block G ₈ of 8T _0, erase the block G ₀ at the same time, scanning between block G ₈ time 18T ₀ ~19T _0, ......, block G _F for a time 31T ₀ ~32T ₀
Block G ₇ is erased at the same time while scanning
The block G _F is scanned between 2T _{0 and} 33T ₀ at time 33T _0.
No block is scanned between ~ 34T ₀ and time 3 again
There is also a method in which while scanning the block G ₀ for 4T _{0 to} 35T _0, the block G ₈ is erased at the same time, and the driving is performed.

In this case, if the combination of the voltage waveforms of FIG. 5 is used to write the pixel and the combination of the voltage waveforms of FIG. 6 is used to erase the pixel, the required scanning time does not change. Further, when the FLC molecule forming the pixel is rewritten to one stable state by the combination of the voltage waveforms in FIG. 6, it is desirable that the pixel be in a dark display state.

In the case of FIG. 11, it seems that all the scan electrodes constituting the liquid crystal display device are divided into 16 sets of scan electrodes, but essentially, "in the time ₀ to 2T ₀ , the blocks G ₀ and G are separated." ₈ are scanned, and blocks G ₀ and G are scanned between times 2T _{0 and} 4T _0.
Scanning the _8, in accordance with the interlaced scanning as it can be with ...... ", scanning the block G ₀ during the" time 0 to T _0, block G ₈ during the time 17T ₀ ~18T ₀
Scanning the scans blocks G ₀ during the time T ₀ ~2T _0, scanning the block G ₈ during the time 18T ₀ ~19T _0, can be understood only by the ...... ".

[0063]

As described above, according to the first invention of the present application, it is possible to perform pixel division which prevents inadvertent pairing with adjacent pixels as shown in FIG. Further, according to the second invention of the present application, different voltages can be applied to partial pixels composed of a plurality of scanning electrodes and one signal electrode, and the ferroelectric liquid crystal forming each partial pixel can be switched separately. Therefore, gradation display is possible.

In particular, according to a preferred embodiment of the present invention,
A ferroelectric liquid crystal display device in which one pixel is composed of a plurality of scanning lines and divided into pixels can be driven with a small drive voltage width when the plurality of scanning lines are simultaneously selected for gradation display. In addition, the controllability of gradation display can be improved.

Further, the direct current balance of the liquid crystal molecules can be kept good. Furthermore, as shown in the fifth embodiment, by using the liquid crystal display device which already became M gradations displayable in the first to fourth invention or the like of the present application, M ^M gradations to 0 to M ^M -1 Can be displayed.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the voltage value of a pulse of the same polarity and the pulse of the opposite polarity and the memory pulse width when the dielectric anisotropy is negative.

FIG. 2 is a schematic configuration diagram of a liquid crystal display device common to the embodiments of the present invention.

FIG. 3 is a plan view showing a pixel portion electrode configuration of an embodiment of the second and fourth inventions.

FIG. 4 is a diagram showing a relationship between a switching pulse width and a continuous pulse in the embodiment of the present invention.

FIG. 5 is a diagram showing voltage waveforms of a preferred embodiment of the third and fourth inventions.

FIG. 6 is a diagram showing voltage waveforms applied before selection voltage application in the third and fourth embodiments of the invention.

FIG. 7 is a diagram showing voltage waveforms applied independently of the third and fourth embodiments of the invention.

FIG. 8 is a diagram showing another voltage waveform of the second invention.

FIG. 9 is a diagram illustrating a 16-gradation display state according to the embodiment of the first invention.

FIG. 10 is a diagram illustrating scanning timing of time division gray scale display according to a fifth embodiment.

FIG. 11 is a diagram illustrating scanning timing of second time division gray scale display according to the fifth embodiment.

12A to 12D are plan views showing an example of the configuration of the pixel electrode of the embodiment of the first invention.

FIG. 13 is an explanatory diagram schematically showing an example of a conventional pixel division method.

FIG. 14 is an explanatory diagram schematically showing an example of a conventional time division method.

Claims (7)

[Claims] 1. A pixel is formed by interposing a ferroelectric liquid crystal at an intersection of a scanning electrode and a signal electrode, a plurality of scanning electrodes forming one pixel are provided, and one pixel is formed by a plurality of partial pixels. A liquid crystal display device including pixels, wherein a ratio of the line widths of a plurality of scanning electrodes forming one pixel is 1: N ^P -1: 1 (N and P are both integers of 2 or more). A ferroelectric liquid crystal display device characterized by the above. 2. A pixel is formed by interposing a ferroelectric liquid crystal at an intersection of a scanning electrode and a signal electrode, a plurality of scanning electrodes constituting one pixel are provided, and one pixel is formed by a plurality of partial pixels. A liquid crystal display device having pixels, wherein a different voltage is independently and simultaneously applied to a plurality of scan electrodes forming one pixel. 3. A pixel is formed by interposing a ferroelectric liquid crystal at an intersection of a scanning electrode and a signal electrode, a plurality of scanning electrodes forming one pixel are provided, and one pixel is formed by a plurality of partial pixels. A liquid crystal display device including pixels, wherein a ratio of the line widths of a plurality of scanning electrodes forming one pixel is 1: N ^P -1: 1 (N and P are both integers of 2 or more). A ferroelectric liquid crystal display device having a negative dielectric anisotropy is used as a ferroelectric liquid crystal, and different waveform voltages are simultaneously applied to a plurality of scan electrodes forming one pixel. , The signal electrode corresponding to the scan electrode has a continuous pulse waveform of the same polarity when the voltage waveform applied to the corresponding partial pixel changes the display state of the partial pixel, and the display state of the partial pixel is changed. If it is not changed, a continuous pulse waveform of opposite polarity Gradation display driving method of the electrode ferroelectric liquid crystal display device comprising applying a so that voltage. 4. A pixel is formed by interposing a ferroelectric liquid crystal at an intersection of a scanning electrode and a signal electrode, a plurality of scanning electrodes forming one pixel are provided, and a plurality of partial pixels form one pixel. A liquid crystal display device having pixels, wherein a ferroelectric liquid crystal display device in which different voltages are simultaneously and independently applied to a plurality of scan electrodes forming one pixel has a negative dielectric anisotropy as a ferroelectric liquid crystal. Having a property of applying a voltage having a different waveform to each of the plurality of scan electrodes forming one pixel at the same time, and applying the voltage to the signal electrode corresponding to the scan electrode to the corresponding partial pixel. The voltage is applied so that the voltage waveform is a continuous pulse waveform of the same polarity when the display state of the partial pixel is changed, and is a continuous pulse waveform of the opposite polarity when the display state of the partial pixel is not changed. That A method for driving gradation display of a characteristic ferroelectric liquid crystal display device. 5. The ferroelectric liquid crystal display device according to claim 3, wherein the product of the time component of the voltage waveform applied to the partial pixel and the voltage is the same for all voltage waveforms. Driving method of gradation display. 6. A liquid crystal display device capable of M gray scale display is used, and all scan electrodes constituting the liquid crystal display device are (1+
M) / 2 or smaller scan electrode groups, and scan one scan electrode group, then scan that scan electrode group, and then scan another scan electrode group. The ferroelectric liquid crystal display device according to claim 1 or 2, wherein 7. A liquid crystal display device capable of M gray scale display is used, and all the scanning electrodes constituting the liquid crystal display device are (1+
M) / 2 or less scan electrode groups, and scan one scan electrode group, then scan that scan electrode group, and then scan another scan electrode group. A gradation display driving method for a ferroelectric liquid crystal display device according to claim 3, 4, or 5.