JPH0799416B2 - Liquid crystal device - Google Patents

Description

The present invention relates to a gray scale display liquid crystal device using an area gray scale method and a driving direction thereof, and more specifically, to a ferroelectric liquid crystal under bistability. The present invention relates to a gradation display liquid crystal device suitable for a display panel such as a liquid crystal television.

[Conventional technology]

In a liquid crystal television panel using the conventional active matrix driving method, thin film transistors (TFTs) are arranged in a matrix for each pixel, and a gate-on pulse is applied to the TFTs to establish a conduction state between the source and the drain. Is applied from the source and accumulated in the capacitor,
A liquid crystal (for example, a twisted nematic-TN liquid crystal) is driven in response to the stored image signal, and at the same time, a gradation display is performed by modulating the voltage of the video signal.

However, in such an active matrix drive type television panel using TN liquid crystal, since the TFT used has a complicated structure, the number of structural steps is large and the high manufacturing cost is a problem. In addition, there is a problem that it is difficult to form a thin film semiconductor (for example, polysilicon or amorphous silicon) forming a TFT over a wide area.

On the other hand, a passive matrix drive type display panel using a TN liquid crystal is known as one that can be manufactured at a low manufacturing cost. In this display panel, one screen (one frame) is displayed as the scanning line (N) increases. The time (duty ratio) during which an effective electric field is applied to one selected point during scanning is reduced by a ratio of 1 / N, which causes crosstalk and does not result in a high-contrast image. In addition to its drawbacks, it is difficult to control the gradation of each pixel by voltage modulation when the duty ratio is low. Therefore, it is not suitable for a display panel with a high-density wiring, especially a liquid crystal television panel.

As a solution to such a fundamental problem of the conventional TN liquid crystal, US Pat.
A ferroelectric liquid crystal element having bistability has been proposed in Japanese Patent No. 67924 and the like.

[Problems to be solved by the invention]

However, in the image display using the above-mentioned bistable ferroelectric liquid crystal, if the state of the ferroelectric liquid crystal molecules has a memory property, the bistable state tries to stabilize in one of two bistable states. Since the intermediate molecular position is not ideally taken at least, the conventional analog-like molecular behavior cannot be obtained, and it is considered to be unsuitable for gradation expression. However, in the gradation display by the dither method, the resolution is lowered and it is not possible to meet the demand for the display quality. Especially, when the electrodes are formed by etching,
It is not preferable because the size of the pixel is limited.

[Means for Solving Problems] and [Operation] An object of the present invention is to solve the above-mentioned drawbacks, and more specifically, in a display panel having high-density pixels over a large area, particularly in a liquid crystal television panel. An object of the present invention is to provide a liquid crystal device for gradation display.

That is, the present invention includes: a.
The striped electrode and the second striped electrode, and along the short direction of the first striped electrode in the intersection where the first striped electrode and the second striped electrode intersect. Matrix electrodes in which the first stripe-shaped electrode is opposed to the second stripe-shaped electrode at a distance so as to form different inter-electrode distances, and the first stripe-shaped electrode is provided on the first stripe-shaped electrode. An alignment control film subjected to a uniaxial alignment treatment along the longitudinal direction of the first stripe-shaped electrode and a chiral smectic liquid crystal arranged at a distance between the first stripe-shaped electrode and the second stripe-shaped electrode were provided. A liquid crystal panel, and b. A second strike on the first stripe-shaped electrode to which the scan signal is applied by sequentially applying a scanning signal to the first stripe-shaped electrode Matrix driving means for applying an information signal to the second stripe-shaped electrode in synchronization with the scanning signal so that a voltage signal according to gradation information is applied to the intersection with the shape electrode, or the second. Scan signals are sequentially applied to the stripe-shaped electrodes of, and a voltage signal according to the grayscale information is applied to the intersection of the first stripe-shaped electrodes on the second stripe-shaped electrodes to which the scan signals are applied. As described above, the liquid crystal device is characterized by having the matrix driving means for applying the information signal to the first stripe-shaped electrode in synchronization with the scanning signal.

〔Example〕

 The present invention will be described below with reference to the drawings.

The ferroelectric liquid crystal used in the present invention has one of a first optical stable state and a second optical stable state depending on an applied electric field, that is, a substance having a bistable state with respect to an electric field, particularly A liquid crystal having such properties is used.

As a ferroelectric liquid crystal having bistability that can be used in the driving method of the present invention, a chiral smectic C-phase (SmC *) or H-phase (SmC *) liquid crystal having ferroelectricity is suitable. . For this ferroelectric liquid crystal, refer to "LE JOURNAL DE
PHYSIQUE LETTER ") 1975, 36 (L-69)," Ferroelectric Liquid Crystals "(" Ferroe
lectric Liquid Crystals ");" Applied Physics Lettere "(19
1980, No. 36 (11), “Sub-micro second bistable estro optics switching in.
Liquid Crystals "(" Submicro Second Bistab
le Electrooptic Switching in Liquid Crystals ”);
"Solid state physics", 1981, 16 (141), "Liquid crystal", etc., and the ferroelectric liquid crystal disclosed therein is also used in the present invention.

More specifically, examples of the ferroelectric liquid crystal compound used in the method of the present invention include desiloxybenzylidene-p'-amino-2-methylbutylcinnamate (DOBAMBC) and hexyloxybenzylidene-p'-amino-. 2-chloropropyl cinnamate (HOBACPC) and 4-o- (2
-Methyl) -butyl resorcylidene-4'-octylaniline (MBRA8) and the like.

When constructing an element using these materials, the element is supported by a copper block with a heater embedded, if necessary, in order to maintain the temperature at which the liquid crystal compound becomes the SmC * phase or SmH * phase. can do.

In addition to the above-mentioned SmC * and SmH *, chiral smectic I
Phase (SmI *), J phase (SmJ *), G phase (SmG *), F phase (S
It is also possible to use a ferroelectric liquid crystal that appears in mF *), K phase (SmK *), or the like.

Further, in the present invention, in addition to the above-mentioned bistable chiral smectic liquid crystal, it can be applied to a chiral smectic liquid crystal having at least two stable alignment states.

FIG. 10 is a schematic drawing of an example of a ferroelectric liquid crystal cell. 1a and 1b are In ₂ O ₃ , SnO ₂ and ITO (Indium-Tin Oxid)
This is a substrate (glass plate) coated with a transparent electrode such as e), in which the SmC * phase oriented so that the liquid crystal molecular layer 2 is perpendicular to the glass surface is filled with liquid crystal. A thick line 3 represents a liquid crystal molecule, and the liquid crystal molecule 3 is
Dipole moment (P⊥) 4 in the direction orthogonal to the molecule
have. When a voltage equal to or higher than a threshold value is applied between the electrodes on the substrates 1a and 1b, the helical structure of the liquid crystal molecules 3 is unraveled, and all the dipole moments (P⊥) 4 are oriented in the electric field direction. Can be changed.
The liquid crystal molecules 3 have an elongated shape and exhibit refractive index anisotropy in the major axis direction and the minor axis direction thereof. Therefore, for example, polarizers arranged in a crossed Nicols positional relationship above and below a glass surface (cross polarized light). It is easily understood that the liquid crystal optical modulation element whose optical characteristics change depending on the polarity of voltage application is provided. Furthermore, when the thickness of the liquid crystal cell is made sufficiently thin (for example, 1 μ), the helical structure of the liquid crystal molecules is untwisted (non-helical structure) and its dipoles are obtained even when no electric field is applied as shown in FIG. The child moment Pa or Pb is either in the upward (4a) or downward (4b) state.
When an electric field Ea or Eb of different polarity equal to or greater than a certain threshold value is applied to such a cell for a predetermined time as shown in FIG. 4, the dipole moment is directed upward 4a or downward depending on the electric field vector of the electric field Ea or Eb. 4b, and the liquid crystal molecules are aligned in either the first alignment state 5a or the second alignment state 5b accordingly.

There are two advantages of using such a ferroelectric liquid crystal as an optical modulation element. First, the response speed is extremely fast, and the alignment of the second liquid crystal molecules has a bistable state. Explaining the second point with reference to FIG. 11, for example, when an electric field Ea is applied, the liquid crystal molecules are aligned in the first alignment state 5a, but this state is stable even when the electric field is cut off. When a reverse electric field Eb is applied, the liquid crystal molecules are in the second alignment state 5b.
The molecules are oriented to change their orientation, but they remain in this state even when the electric field is turned off. Also, unless the applied electrode Ea exceeds a certain threshold value, the respective alignment states are also maintained. In order to effectively realize such a high response speed and bistability, it is preferable that the cell is as thin as possible, generally 0.5 μ to 20 μ, particularly 1 μ.
~ 5μ is suitable. A liquid crystal-electro-optical device having a matrix electrode structure using a ferroelectric liquid crystal of this kind has been proposed by Clark and Lagabal in US Pat. No. 4,367,924.

The present invention is to improve the cell structure when used in a ferroelectric liquid crystal having at least two stable states, particularly in a state having the bistability of the above-mentioned ferroelectric liquid crystal. By changing the layer thickness of the organic liquid crystal continuously or stepwise, and also by continuously or stepwise changing the interval between the pair of electrodes in response to this layer thickness change,
This enables desired gradation display.

As described above, the ferroelectric liquid crystal element having bistability can change the alignment direction of the liquid crystal by applying two electric fields of different polarities to each other, thereby performing optical modulation.

In the present invention, a device using a ferroelectric liquid crystal is generally driven by applying a rectangular pulse to a liquid crystal layer from between a pair of electrodes. Ferroelectric liquid crystal has a rapid threshold characteristic with respect to an electric field given by a rectangular pulse. That is, there is no response below a certain electric field, but above a certain electric field, for example, a transition between two stable states occurs. In the present invention, the liquid crystal layer film and the electrode spacing in one pixel are provided with a change distribution to generate a difference in the electric field strength when a voltage pulse within the pixel is applied, and the electric field strength causes Since there are regions that are inverted and regions that are not inverted, it is possible to control gradation by the ratio of the inverted regions.

FIG. 1 is a cross-sectional view showing a typical example of the liquid crystal element of the present invention.

The gradation display liquid crystal element 11 shown in FIG.
Has a distribution in which the film thickness of the transparent electrode 13 changes stepwise to d ₁ , d ₂ , d ₃ and d _4, and the pair of transparent electrodes 13a
The distance between the (step electrode) and 13b (flat electrode) has a distribution that changes stepwise. A substrate 14a such as a glass plate or a plastic film for forming a film thickness having the above-mentioned changed distribution and an electrode interval having the changed distribution.
A step insulating film 15 is formed on the surface. Further, orientation control films 16a and 16b having a wall effect for orienting the smectic molecular layer of the ferroelectric liquid crystal 12 preferentially in one direction can be formed on the transparent electrodes 13a and 13b, respectively.

As described above, the ferroelectric liquid crystal 12 having the film thicknesses d ₁ , d ₂ , d ₃ and d ₄
Since the electric field strength applied to each of the film thickness regions is different, a pulse signal with a voltage peak value according to the gradation or a signal with a pulse width or pulse number according to the gradation is applied.
Gradation can be expressed by forming regions in the pixel that exceed the inversion threshold voltage and regions that do not exceed the inversion threshold voltage in accordance with the film thicknesses d _{1 to} d ₄ .

Further, in the present invention, prior to applying the above-mentioned gradation signal,
After the erasing step for setting the pixel to either the bright state or the dark state, the inversion voltage for inverting the state is controlled according to the gradation and applied to the ferroelectric liquid crystal. It is necessary.

FIG. 2 schematically shows a method of applying an electric signal, and FIGS. 3 and 4 show the electric signal. FIG. 3 shows the waveform of the signal (a) generated by the drive circuit 23 of FIG.
4 (a) to 4 (e) show the waveforms of the signal (b) generated in the drive circuit 23 of FIG.

An erasing step for providing a 12 V 1 msec pulse as the signal (a) and a -8 V 1 msec pulse in synchronism beforehand (this is called an erasing pulse) is provided as the signal (a). Then, the liquid crystal is switched to the first stable state, and the entire pixel A is in the bright state (the cross polarizing plate is arranged in this way). From this state, FIG.
A gradation signal having various pulses as shown in (e) is applied as a signal (b) to the transparent step electrode 13a in synchronism with the pulse shown in FIG. 3, whereby the optical state of the pixel A is shown in FIG. The states shown in (a) to (e) can be set.

The display state shown in FIG. 5 (a) is a state when the pulse (OV) shown in FIG. 4 (a) is applied, and the bright state 51 at the previous erase step is maintained as it is. FIG. 5 (b)-
In the display state shown in (d), the pulses shown in FIGS. 4 (b) to (d) corresponding to the halftone signals are applied, and the bright state 51 changes to the dark state 52 depending on the film thickness d _{1 to} d _4. The state is inverted.

That is, FIG. 5 (b) shows −2V, 1 shown in FIG. 4 (b).
When a pulse of msec is applied, the region corresponding to the film thickness d ₁ in the pixel A is displayed in a dark state. FIG. 5C shows a display state in which the region corresponding to the film thickness d ₁ and d ₂ in the pixel A is inverted to the dark state when the −4V, 1 msec pulse shown in FIG. 4C is applied. Fig. 5 (d) shows that when a pulse of -6V, 1msec shown in Fig. 4 (d) is applied,
The region corresponding to the film thicknesses d ₁ , d ₂ and d ₃ in the pixel A represents the display state in which the dark state is inverted.

Then, the display state of FIG. 5 (e) is the film thickness d ₁ in the pixel A,
The area corresponding to d ₂ , d ₃ and d ₄ , that is, the entire pixel A is in the state of being inverted to the dark state 52.

Further, the present invention has a matrix electrode structure in which the transparent flat electrode 13b shown in FIG. 2 has a stripe shape, the transparent step electrode 13a has a stripe shape, and the transparent electrodes 13a and 13b cross each other. You can

In the driving method of the present invention, the gradation can be reproduced by changing the frequency according to the gradation. FIG. 6 shows a specific example thereof. That is, FIG. 6 (a)-
As shown in FIG. 5E, the gradation shown in FIG. 5 can be obtained by applying a signal having a pulse width corresponding to the gradation in place of the pulse in FIGS. 4A to 4E described above. Can be displayed. At this time, the pulses shown in FIGS. 6B to 6C correspond to the halftone signal. Further, in the present invention, similar gradation display can be performed by changing the number of pulses.

In the liquid crystal element shown in FIGS. 1 and 2, only the transparent electrode on one side is used as the transparent step electrode, but in the liquid crystal element of the present invention, the two transparent electrodes paired on both sides are transparent step electrodes. Can be

FIG. 7 is a sectional view showing another mode of the liquid crystal element of the present invention. The liquid crystal element shown in FIG. 7 has a wedge-shaped insulating film 72 and a transparent electrode formed thereon in order to form a distribution in which the distance between the pair of electrodes and the film thickness of the ferroelectric liquid crystal continuously change. 71 are provided.

The orientation control films 16a and 16b used in the present invention include, for example,
Inorganic insulating materials such as silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide and boron nitride, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, Uniaxiality such as rubbing treatment on a film formed using an organic insulating material such as polyparaxylelin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin or acrylic resin An alignment control film that has been subjected to an alignment treatment can be used.

Further, the step insulating film 15 used in the liquid crystal element of the present invention can be obtained by repeating the photolithographic technique, and as the insulating material used at this time, a photo-resist resin is suitable, but polyvinyl alcohol, It is also possible to use polystyrene, cellulose resin, resin such as polyamide or polyimide.

FIG. 8 shows a concrete example when the gradation expression method according to the present invention is applied to matrix driving.

In the display panel shown in FIG. 8, a plurality of stripe-shaped transparent step electrodes 81 (81a, 81b, --81g) are arranged on a glass substrate. The stripe-shaped transparent flat electrode 82 (82a, 82b,-82-82) facing the transparent step electrode 81
f) is wired so as to cross the transparent step electrode 81, and the ferroelectric liquid crystal is arranged between the pair of transparent electrodes 81 and 82.

In the matrix driving method of the present invention, all or a predetermined portion of the pixels formed at the intersections of the stripe-shaped transparent step electrode 81 and the stripe-shaped transparent flat electrode 82 prior to writing are either in a bright state or a dark state at a time. It is possible to use a method of writing a gradation image by sequentially applying a writing signal accompanied by a gradation signal for each row to the pixels on the row from one state, and before writing one line. After setting all or a predetermined part of the pixels on the row to either the bright state or the dark state, the step of applying the write signal accompanied by the gradation signal to the pixels on the row is sequentially performed for each row. A method of writing gradation pixels can be used. These driving methods are disclosed in, for example, JP-A-59-193427 and JP-A-60-156047, which are suitable driving examples in the present invention.

In the driving method of the present invention, the striped transparent step electrode 81
As a scanning electrode group, a scanning signal is applied to the scanning electrode group, and the opposing stripe-shaped transparent flat electrode 82 is used as a signal electrode group to selectively apply the gradation signals shown in FIG. 4 or FIG. Writing can be performed. Conversely, writing can also be performed by applying a scanning signal or a voltage to the stripe-shaped transparent flat electrode 82 and selectively applying a gradation signal to the other stripe-shaped transparent step electrode 81. You can

Hereinafter, detailed examples of the present invention will be described.

Example 1 A step insulating film shown in FIG. 1 was formed on a glass plate by an acrylic negative resist resin (“RFG” of Sekisui Fine Chemical), and ITO serving as a stripe-shaped transparent step electrode was formed on the step insulating film. A polyimide film having a film thickness of 1000Å is provided over one surface (the polyimide film is 5% by weight of polyamic acid N- which is a dehydration condensation product of pyromellitic dianhydride and 4,4'-diamidediphenyl ether).
After applying the methylpyrrolidone solution, it was formed by causing a dehydration ring closure reaction by heating at a temperature of 180 ° C.).
A rubbing process was performed along the longitudinal direction of the stripe electrode. This was used as the A electrode plate.

Next, facilitate another glass plate, provide a striped ITO film on it, then provide a 1000 Å polyimide film similar to that used when the A electrode plate was created, and then make this flat striped film. The rubbing treatment was performed in the direction perpendicular to the longitudinal direction of the electrode. This was used as a B electrode plate.

Then, so that the striped electrodes are orthogonal to each other (so that the rubbing directions are parallel), A
The electrode plate and the B electrode plate were overlapped with each other, and the periphery thereof was sealed with an epoxy adhesive except for a portion serving as an injection port to form a cell. Then, the following composition under isotropic phase was injected into the cell under vacuum, and then the injection port was sealed. Then 0.5
A bistable chiral smectic phase ferroelectric liquid crystal device was prepared by gradually cooling at a rate of ° C / hour.

Composition The phase transition mode of the above composition was as follows.

Phase transition mode In the formula, ch is the cholesteric phase, SmA is the smectic A
Phase, SmB indicates smectic B phase) The electric field response characteristics of this composition in the chiral smectic phase are shown in FIG. 9 (however, the liquid crystal film thickness at this time was 1.0 μm). The characteristic curve shown in Fig. 9 is obtained by applying a bistable chiral smectic phase cell with a thickness of 1.0 µm to a cell under orthogonal Nicols.
It was obtained by measuring the amount of transmitted light when a rectangular pulse having a pulse width of 1 msec was applied. It can be seen from FIG. 9 that when the rectangular pulse having the pulse width of 1 msec is applied, the reverse switching is performed from the first stable alignment state to the second stable alignment state with the electric field strength of 13 V / μm.

Further, the film thickness of the liquid crystal in the above-mentioned ferroelectric liquid crystal element and the electric field strength at the time of reversal switching with this film thickness were measured.
The results are shown in Table 1.

Table 1 Field strength of ferroelectric liquid crystal during film thickness inversion switching d ₁ = 0.9 μm 11.7V d ₂ = 1.1 μm 14.3V d ₃ = 1.3 μm 16.9V d ₄ = 1.5 μm 19.5V Ferroelectric liquid crystal prepared in this way 1msec at 12V for all stripe-shaped transparent flat electrode groups on the B electrode plate in the device
By simultaneously applying the rectangular pulse of 1 msec at −8 V to all the stripe-shaped transparent step electrode groups on the A electrode plate at the same time, all the pixels were temporarily cleared to the dark state. Next, a rectangular pulse of 12 V and 1 msec shown in FIG. 3 is sequentially applied to each of the stripe-shaped flat electrodes of the B electrode plate as a scanning selection signal for each row, and when scanning is not selected.
OV was applied. The stripe-shaped transparent step electrode of the A electrode plate is synchronized with the scanning selection signal by the OV shown in FIG.
1msec at -2V, 1msec at -4V, 1msec at -6V and 1ms at -8V
When a rectangular pulse of ec was applied according to the gradation information, it was possible to display an image with good gradation in which flicker was suppressed. Further, in the present example in which the rubbing treatment along the longitudinal direction of the stripe-shaped step electrodes was performed on the above-mentioned A electrode plate, in the comparative experiment example obtained by performing the rubbing treatment along the lateral direction of such electrodes. Compared to
The controllability and reproducibility of the voltage signal of the inversion area generated by the application of the voltage signal having the gradation information is high, and thus high gradation reproducibility is obtained.

〔The invention's effect〕

As described above, it is possible to provide a liquid crystal device that can realize gradation display of a liquid crystal element having bistability, which has been considered difficult until now, while suppressing the occurrence of flicker under matrix driving.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid crystal element of the present invention. FIG. 2 is an explanatory diagram showing a specific mode of the liquid crystal element of the present invention. FIGS. 3 and 4 (a) to 4 (e) are explanatory views showing a scan selection signal and a gradation signal used in the driving method of the present invention, respectively. FIGS. 5A to 5E are explanatory diagrams schematically showing the gradation display state appearing in the pixel. 6 (a) to 6 (e) are explanatory views showing another gradation signal used in the driving method of the present invention. FIG. 7 is a sectional view showing another mode of the liquid crystal element of the present invention. FIG. 8 is a plan view of a matrix electrode used in the liquid crystal element of the present invention. 9th
The figure is an explanatory view showing the relationship between the electric field strength and the amount of transmitted light in the ferroelectric liquid crystal used in the present invention. 10 and 11 are perspective views schematically showing a ferroelectric liquid crystal used in the present invention.

Front Page Continuation (72) Inventor Yutaka Inaba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Shinjiro Okada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-51-41920 (JP, A) JP-A-47-23196 (JP, A) JP-A-47-24827 (JP, A) JP-A-60-123825 (JP, A) Kai 60-229012 (JP, A)

Claims (3)

[Claims] 1. A first stripe-shaped electrode and a second stripe-shaped electrode, which are arranged to intersect each other with a space therebetween, wherein the first stripe-shaped electrode and the second stripe-shaped electrode intersect each other. In the intersection, the first stripe-shaped electrode is arranged to face the second stripe-shaped electrode so as to face each other so as to form different inter-electrode distances along the lateral direction of the first stripe-shaped electrode. Matrix electrode, first
An alignment control film which is provided on the stripe-shaped electrode and is subjected to a uniaxial alignment treatment along the longitudinal direction of the first stripe-shaped electrode; and a first stripe-shaped electrode and a second stripe-shaped electrode. A liquid crystal panel provided with a chiral smectic liquid crystal arranged at intervals of b., B. A scanning signal is sequentially applied to the first stripe-shaped electrode, and a second stripe on the first stripe-shaped electrode to which the scanning signal is applied. Matrix driving means for applying an information signal to the second stripe-shaped electrode in synchronization with the scanning signal so that a voltage signal corresponding to gradation information is applied to the intersection with the stripe-shaped electrode, or A scanning signal is sequentially applied to the two stripe-shaped electrodes, and the grayscale information is applied to the intersection of the first stripe-shaped electrode on the second stripe-shaped electrode to which the scanning signal is applied. And as the voltage signal is applied, the liquid crystal device having a matrix drive means for applying an information signal to the first stripe-shaped electrode in synchronization with the scanning signal. 2. The liquid crystal device according to claim 1, wherein the uniaxial alignment treatment is a rubbing treatment. 3. The matrix driving means sequentially applies a scanning signal to the first stripe-shaped electrode, and an intersection of the first stripe-shaped electrode to which the scanning signal is applied and a second stripe-shaped electrode. Then, the information signal is applied to the second stripe-shaped electrode in synchronization with the scanning signal so that the voltage signal according to the gradation information is applied, and prior to the application of the information signal in synchronization with the scanning signal. , An erase voltage signal for orienting the chiral smectic liquid crystal in one orientation state is provided between the electrodes at the intersections of the first stripe-shaped electrodes to which the scanning signal is applied and all or a predetermined number of second stripe-shaped electrodes. The liquid crystal device according to claim 1, further comprising means for erasing a written state at the intersection in advance by applying the voltage.