JP2003195314A - Method for manufacturing liquid crystal element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To apply uniform alignment treatment to the whole area of a panel. <P>SOLUTION: In the case of fabricating a liquid crystal panel using a chiral smectic liquid crystal, a DC voltage is sometimes applied to the liquid crystal which is just at the point in time of phase transition from a Ch (cholesteric) phase to a SmC* (chiral smectic C) phase for the purpose of imparting deviation to an internal potential inside a cell (refer to sign B<SB>2</SB>of the figure). Before application of the DC voltage (refer to sign B<SB>1</SB>of the figure), a DC voltage with a reverse polarity is applied. Alignment controlling layers are charged by this voltage application, and the charge component ΔV is applied to the liquid crystal during the period B<SB>2</SB>and consequently alignment treatment of the liquid crystal is thoroughly carried out. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a liquid crystal element.

[0002]

2. Description of the Related Art In recent years, liquid crystal panels have been used in viewfinders and projectors of video camcorders as well as monitors for personal computers, but twisted nematic liquid crystals are generally used. However, this twisted nematic liquid crystal has problems of slow response speed and narrow viewing angle, and a liquid crystal free from such problems is desired. For example, there is a field sequential method as one method of displaying in color on a liquid crystal panel. In this method, by irradiating the liquid crystal panel with red (R), green (G), and blue (B) light, a black-and-white image on the liquid crystal panel is recognized as each color image, and light colors and images are switched in a short time. By doing so, it is possible to recognize as a full-color image by utilizing the afterimage phenomenon of the human eye.
In this method, it is essential that the response speed of the liquid crystal is fast.

As a liquid crystal that solves such a problem, there is a chiral smectic liquid crystal such as a ferroelectric liquid crystal, which is disclosed in Japanese Unexamined Patent Publication No. 2000-10076 and 2000-3384.
Japanese Patent Publication No. 64 discloses a liquid crystal panel using a monostable mode ferroelectric liquid crystal or an active matrix element. In the monostable mode ferroelectric liquid crystal, as shown in FIG. 2, when a voltage of one side polarity (+ Vx in the figure) is applied, the light transmittance T is largely changed according to the magnitude of the applied voltage. However, when a voltage of the other polarity (-Vx in the figure) is applied, the light transmittance T is increased regardless of the magnitude of the applied voltage.
Indicates a characteristic that does not change much. In such a liquid crystal, it is necessary to perform a treatment for imparting a bias to the internal potential in the cell in the process of transition from the cholesteric (Ch) phase of the liquid crystal material to the chiral smectic C (Sm-C ^* ) phase. , Ch-SmC ^* A DC voltage of either positive or negative polarity may be applied to the liquid crystal during the phase transition.

[0004]

(1) By the way, in the case of performing the DC voltage application process as described above, the liquid crystal panel at room temperature undergoes a phase transition from the Sm-C * phase to the Ch phase. Heating, and then, in the process of cooling, start voltage application when the liquid crystal is in the Ch phase, and continue applying voltage until the liquid crystal undergoes a phase transition from the Ch phase to the Sm-C * phase, There is.

The heating of the liquid crystal panel in such a case is generally
Is performed by the panel heater, but the entire panel surface is leveled.
It is difficult to raise the temperature all the way to the center of the panel.
Temperature rises faster than in the peripheral area of the panel.
If you stop heating in that state, the panel center will
The temperature will drop more slowly than in the peripheral area of the flannel. Figure 1
1 is the temperature rise in the panel center and the panel periphery
It is a figure which shows the difference in temperature drop. That is, on the vertical axis
The temperature is taken and the horizontal axis is the time. ₁Added
Indicates the heat period (the period when the panel heater is on),
Code A_TwoIs the temperature drop period (the period after turning off the panel heater)
Interval). And the curve 100 is in the center of the panel.
Shows how the temperature changes (temperature rises and falls) at any point
The curve 101 indicates the temperature change at any point around the panel.
The state of (temperature increase and temperature decrease) is shown. Such warmth
In the case of a liquid crystal panel that has a degree history, start of DC voltage application
Timing is when the liquid crystal around the panel is in the Ch phase
(See t1), and the DC voltage application is completed.
The liquid crystal in the center of the panel has a phase transition to the Sm-C * phase.
(See reference numeral t2), the application time is
It takes a long time of about 10 minutes.

(2) However, during such a DC voltage application, the orientation control film is charged, and the voltage applied to the liquid crystal decreases with time (see reference numeral 111 in FIG. 12).

This phenomenon will be described below with reference to FIGS. 4 and 12. Here, FIG. 4 is a circuit diagram showing an equivalent circuit of the liquid crystal panel, and FIG. 12 is a diagram showing a change in potential in an arbitrary portion of the liquid crystal panel.

The liquid crystal panel can be represented by an equivalent circuit as shown in FIG. That is, the alignment control film 6 is arranged in contact with the liquid crystal 2, and the pixel electrode 3b and the common electrode 3a are arranged so as to sandwich them. Reference numeral 4 represents a TFT connected to each pixel electrode 3b, and Ri
ns is the resistance of the alignment control film, Cins is the capacitance of the alignment control film, Rlc is the resistance of the liquid crystal layer, and Clc is the capacitance of the liquid crystal layer. In the liquid crystal panel having such a configuration, the above-mentioned DC voltage is applied between the pixel electrode 3b and the common electrode 3a (see the curve 110 in FIG. 12). However, when the DC voltage is applied for a long time, the alignment control film 6 connected in series to the liquid crystal 2 is charged with time, and the voltage applied to the liquid crystal 2 is the curve 1
As shown in 11, it decreases with time.

Such a charging phenomenon of the orientation control film can be easily confirmed by experiments. That is, D as described above
After applying C voltage for 10 minutes, the pixel electrode 3b and the common electrode 3
As a result of short-circuiting with a, a voltage having a reverse polarity to the applied DC voltage is applied to the liquid crystal layer, and the liquid crystal 2 is
It came to respond to a voltage with a polarity different from the C voltage (anti-electric field response).

(3) That is, the temperature of the liquid crystal panel when the temperature is lowered is non-uniform and varies from pixel to pixel (see FIG. 11), and the above DC voltage (voltage applied to the electrodes 3a and 3b) is The voltage applied to each pixel in the same manner and the voltage actually applied to the liquid crystal 2 is indicated by reference numeral 1 in FIG.
As indicated by 11, it changes (decreases) with time. Therefore, the voltage applied to the liquid crystal 2 during the phase transition from the Ch phase to the Sm-C * phase varies depending on each pixel, and the alignment of the liquid crystal may be affected.

Particularly, in a pixel in which the phase transition to the Sm-C * phase is slow (see symbol t2 in FIG. 11), the applied voltage may be close to 0V, and the voltage application process may not be completed. There is.

Therefore, it is an object of the present invention to provide a method of manufacturing a liquid crystal element which prevents liquid crystal alignment defects.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and a step of arranging a pair of substrates with a predetermined gap left therebetween and a chiral smectic liquid crystal in the gap between the pair of substrates. A step of disposing an alignment control film in contact with the chiral smectic liquid crystal, and a step of sandwiching the chiral smectic liquid crystal and disposing a first electrode and a second electrode so as to form a plurality of pixels. In the method for manufacturing a liquid crystal element, the first voltage applying step of applying a DC voltage of one polarity to the liquid crystal and the DC voltage of another polarity from the cholesteric (Ch) phase to the chiral smectic C (Sm-C ^* )
It is characterized in that a second voltage applying step of applying to the liquid crystal at the time of phase transition is sequentially performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIG.

(1) First, the structure of a liquid crystal element manufactured by applying the present invention will be described with reference to FIG.

A liquid crystal device manufactured by applying the present invention, as shown by a symbol P in FIG. 1, has a pair of substrates 1a and 1b arranged with a predetermined gap therebetween, and the pair of substrates 1a. , 1b, a chiral smectic liquid crystal 2 and alignment control films 6a and 6b arranged so as to be in contact with the liquid crystal 2 to control the alignment state thereof, and form a plurality of pixels and sandwich the liquid crystal 2 therebetween. The first electrode 3a and the second electrode 3b are arranged in such a manner that they are driven by applying a voltage to the chiral smectic liquid crystal 2 through the first electrode 3a and the second electrode 3b. Is configured. The active element 4 may be arranged in each pixel and the active element 4 may be connected to the second electrode 3b.

(2) Next, a method for manufacturing a liquid crystal element according to the present invention will be described.

In manufacturing the above-mentioned liquid crystal element, a step of arranging the pair of substrates 1a and 1b with a predetermined gap left between them, and a chiral smectic liquid crystal 2 in the gap between the pair of substrates 1a and 1b. A step of arranging the orientation control films 6a and 6b so as to contact the chiral smectic liquid crystal 2, and a first electrode 3a and a second electrode which sandwich the chiral smectic liquid crystal 2 and form a plurality of pixels. The step of disposing the electrode 3b and the step of arranging the electrode 3b are performed in an appropriate order.

After that, .Applying a DC voltage of one polarity to the liquid crystal 2
(Code B in FIGS. 6, 8 and 10 ₁reference. Hereafter, "the first voltage mark
"Additional process") ・ For DC voltage of other polarity, cholesteric (Ch) phase
From chiral smectic C (Sm-C^*) Phase transition
Applying to the liquid crystal 2 at the time of
Issue B_Tworeference. Hereinafter, referred to as “second voltage applying step”),
Are sequentially carried out.

As shown in FIG. 3, the second electrode 3
a step of arranging the active element 4 in each pixel in a state of being connected to b, a step of connecting a gate line driving circuit 7 to a gate of the active element 4, and a source line driving circuit 8 connected to a source of the active element 4. And a step of
Performed before the voltage application step, and the first voltage application step, (reference symbol B ₁ in Fig. 6 and 8) it is carried out by sequentially applying a pulse voltage to-the active element 4, - all Alternatively, it may be performed in a state where a constant voltage is continuously applied to the active element 4 (see reference numeral B _{1 in} FIG. 10).

Further, between the first voltage applying step and the second voltage applying step, a step of setting the potential difference between the first electrode 3a and the second electrode 3b to approximately 0 V may be performed. good.

(3) Next, the detailed structure of the liquid crystal element will be described.

(3-1) The chiral smectic liquid crystal 2 will be described. As the chiral smectic liquid crystal 2 used in the present embodiment, the isotropic liquid phase (IS
O. ) -Cholesteric phase (Ch) -Chiraral smectic C phase (SmC *) or isotropic liquid phase (ISO.)-
A chiral smectic C phase (SmC *) having a phase transition series may be used. Specifically, the following (1) to
The compound shown in (4) can be mentioned.

[0024]

[Chemical 1] _{R 1,} R 2: an alkyl group _X 1 having 1 to 20 carbon atoms and is optionally substituted linear or _{branched, X} 2: single _{bond, O, COO, OOC Y 1} , Y ₂ , Y ₃ , Y ₄ : H or F n: 0 or 1

[0025]

[Chemical 2] _{R 1,} R 2: an alkyl group _X 1 having 1 to 20 carbon atoms and is optionally substituted linear or _{branched, X} 2: single _{bond, O, COO, OOC Y 1} , Y ₂ , Y ₃ , Y ₄ : H or F

[0026]

[Chemical 3] _{R 1,} R 2: an alkyl group _X 1 having 1 to 20 carbon atoms and is optionally substituted linear or _{branched, X} 2: single _{bond, O, COO, OOC Y 1} , Y ₂ , Y ₃ , Y ₄ : H or F

[0027]

[Chemical 4] _{R 1,} R 2: an alkyl group _X 1 having 1 to 20 carbon atoms and is optionally substituted linear or _{branched, X} 2: single _{bond, O, COO, OOC Y 1} , Y ₂ , Y ₃ , Y ₄ : H or F

By the way, in the present embodiment, for the chiral smectic liquid crystal 2, the composition of the liquid crystal material is adjusted, and further, the treatment of the liquid crystal material and the element constitution, for example, the materials of the orientation control films 6a and 6b, the treatment conditions, etc. By setting appropriately, when the drive voltage is not applied, the average molecular axis (liquid crystal molecule) of the liquid crystal shows an alignment state in which the liquid crystal molecules are mono-stabilized, and the drive voltage of one polarity is applied to drive. In this case, the average molecular axis of the liquid crystal molecules tilts from the mono-stabilized position to one side at an angle according to the magnitude of the driving voltage, and the other polarity (reverse polarity to the one polarity is set). Hereinafter, when the same voltage is applied, the average molecular axis of the liquid crystal molecules is at an angle corresponding to the magnitude of the driving voltage from the mono-stabilized position on the other side (that is, the one side). Mark the polarity voltage May the side to tilt when tilt in the opposite side), as shown in the characteristic way. That is, the liquid crystal 2 used in the present embodiment is one in which the original memory property (bistability) of the chiral smectic liquid crystal is lost, and the magnitude of the tilt angle can be continuously controlled by the applied voltage. Accordingly, the light quantity of the liquid crystal element can be continuously changed, and gradation display is possible. In this case, the tilt angle in the maximum tilt state by applying the drive voltage of the one polarity may be different from the tilt angle in the maximum tilt state by applying the voltage of the other polarity. good. For example, as shown in FIG. 2, when a voltage of another polarity is applied, the average molecular axis of the liquid crystal may hardly tilt regardless of the magnitude of the voltage.

(3-2) Next, the chiral smectic liquid crystal 2
Each component other than the above will be described.

For the substrates 1a and 1b described above, a highly transparent material such as glass or plastic may be used.

The electrodes 3a and 3b may be made of a material such as In ₂ O ₃ or ITO (indium tin oxide), and these electrodes 3a and 3b may be formed on the respective substrates 1a and 1b. . The second electrodes 3b to which the active elements 4 are connected are arranged in a dot-like matrix, and the other first electrodes 3a are preferably formed on substantially the entire surface (or a specific region) of the substrate 1a. further,
The active element 4 may be a TFT or MIM (Meta).
l-Insulator-Metal) or the like may be used.

Further, at positions contacting the chiral smectic liquid crystal 2, alignment control films 6a and 6b subjected to uniaxial alignment treatment for controlling the alignment state thereof may be arranged. As the alignment control films 6a and 6b, those obtained by applying a solution of an organic material such as polyimide, polyimideamide, polyamide, or polyvinyl alcohol to form a film, and subjecting the surface of the film to a rubbing treatment, An oblique vapor deposition film formed by vapor-depositing an inorganic material such as an oxide such as SiO or a nitride on the substrates 1a and 1b at a predetermined angle from an oblique direction, * Optical alignment capable of generating a uniaxial alignment regulating force by ultraviolet irradiation or the like The thing using a membrane can be mentioned. In addition,
Depending on the material of the alignment control films 6a and 6b and the conditions of the uniaxial alignment treatment, the pretilt angle of the liquid crystal molecules (that is, the angle formed by the liquid crystal molecules with respect to the alignment control films 6a and 6b near the interface between the alignment control films 6a and 6b). ) Is adjusted.

Such alignment control films 6a and 6b may be arranged on both sides of the chiral smectic liquid crystal 2 and both of them may be subjected to uniaxial alignment treatment. In that case, the relationship of the uniaxial alignment treatment direction (particularly the rubbing direction). Takes into account the liquid crystal material used, * anti-parallel (both uniaxial alignment treatment directions are parallel and opposite directions), * parallel (both uniaxial alignment treatment directions are parallel and same directions), * crosses within 45 ° It can be set so that it is either relationship or. 45 °
The relationship of crossing in the following range is a case where two vectors (vectors indicating the uniaxial orientation processing directions) cross in a range of 45 ° or less, and the respective vector directions are in the same direction (to be exact, 45 There is an angle deviation of less than °.)
And the case where the respective vector directions are opposite directions. When the value of the crossing angle (narrower crossing angle) between the vectors is 45 ° or less and close to 0 °, the relation between the respective vectors is regarded as a substantially antiparallel or parallel relation. Good. Further, the above-mentioned anti-parallel or parallel relationship may be regarded as a substantially anti-parallel or parallel relationship, in addition to the fact that the vectors are always parallel to each other, for example, even when they are deviated by several degrees. In the present specification, the orientation control film refers to a film which has some influence on the alignment of the liquid crystal by being in direct contact with the liquid crystal, in addition to the film subjected to the uniaxial alignment treatment. In addition,
The alignment control films on both sides may not be subjected to the uniaxial alignment treatment, but the alignment control films on one side may be subjected to the uniaxial alignment treatment.

Further, a spacer (not shown) made of silica beads or the like is arranged in the gap between the substrates 1a and 1b,
The gap size may be defined by such a spacer. It should be noted that the gap size may be adjusted so as to be in an optimum range in consideration of the liquid crystal material, but it is possible to achieve uniform uniaxial orientation and to determine the average molecular axis of liquid crystal molecules in the state where no voltage is applied. It is preferable to set it in the range of 0.3 to 10 μm in order to substantially coincide with the axis of the average orientation direction axis.

Furthermore, if adhesive particles (not shown) made of epoxy resin or the like are dispersed in the gaps between the substrates 1a and 1b to improve the adhesiveness between the substrates 1a and 1b and the impact resistance of the liquid crystal element. good.

Further, the liquid crystal element may be of a transmissive type or a reflective type. In the case of the transmissive type, both substrates 1a and 1b need to be transparent, and in the case of the reflective type, one of the substrates 1a and 1b needs to have a function of reflecting light. Here, as a method of imparting a function of reflecting light, * a method of providing a reflection plate or a reflection film separately from the substrate 1a or 1b, or a method of forming the substrate 1a or 1b itself with a reflection member, or , And the like. Here, in the case of a transmissive liquid crystal element, polarizing plates may be arranged on both substrates 1a and 1b (so that their polarization axes are orthogonal to each other), and in the case of a reflective liquid crystal element, at least one of them may be arranged. Substrate 1a or 1
A polarizing plate may be provided on b.

(4) Next, the effect of this embodiment will be described.

According to the present embodiment, the liquid crystal 2 includes
From cholesteric (Ch) phase to chiral smectic C
A DC voltage is applied when transitioning to the (Sm-C ^* ) phase, but before that, a voltage having a polarity opposite to that of the DC voltage is applied, so that the voltage value applied to the liquid crystal layer is maintained. A good alignment state can be obtained.

[0039]

The present invention will be described in more detail below with reference to examples.

Example 1 In this example, a liquid crystal panel (liquid crystal element) P shown in FIGS. 1 and 3 was produced.

That is, as shown in FIG. 3, on one substrate 1b side, a large number of gate lines G _i (i = 1, 2, ...) Are arranged laterally in the drawing (only one is shown in the drawing). , Source lines S _j (j = 1, 2, ...) Are arranged in the vertical direction in the figure (only one line is shown in the figure). And these gate lines G
A thin film transistor (amorphous SiTF) as an active element is provided at a pixel at each intersection of _i and the source line S _j.
T) 4 and the pixel electrode (second electrode) 3b are formed.

Further, as shown in FIG. 1, a substrate 1a was arranged so as to face the substrate 1b, and a common electrode (first electrode) 3a was formed on the substrate 1a. And the substrate 1
The gap between a and 1b, the pixel electrode 3b and the common electrode 3a
Between them and the chiral smectic liquid crystal 2 having spontaneous polarization was arranged in contact with the alignment control films 6a and 6b.
Further, the gate electrode of the TFT 4 is the gate line G _i described above.
The source electrode 47 of the TFT 4 is connected to the information signal driver (source line drive circuit) 8 via the source line S _j .

The liquid crystal panel manufactured in this embodiment can be replaced with an equivalent circuit as shown in FIG. 4, but the applied voltage (NodeA-NodeC) and the voltage of the liquid crystal layer (NodeB-NodeC) are different. As shown in FIG.

When manufacturing this liquid crystal panel, 2
The common electrode 3a, the pixel electrode 3b, the TFT 4, etc. were formed on the respective surfaces of the substrates 1a, 1b, and the alignment control films 6a, 6b were formed so as to cover them. Then, spacers were scattered and the pair of substrates 1a and 1b were bonded together. Then, the liquid crystal 2 was injected into the gap between the substrates from the liquid crystal injection port, and the injection port was sealed. Further, the scanning signal driver 7 was connected to the gate line of the liquid crystal panel, and the information signal driver 8 was connected to the source line.

The liquid crystal panel P thus manufactured is
It was placed on the surface heater 50 as shown in FIG. A temperature controller 51 is connected to the surface heater 50 so that its temperature can be controlled, and a drive controller 52 is connected to the liquid crystal panel P.
Was connected to enable voltage application. Then, a soaking material 53 such as silicone rubber is placed on the upper surface of the liquid crystal panel P so that the liquid crystal panel P is heated (or cooled) at a relatively uniform temperature. In addition, the liquid crystal panel P
A temperature sensor 54 is attached to the panel so that the panel temperature can be detected. It should be noted that the temperature distribution occurs on the liquid crystal panel, but it is necessary and sufficient to measure the temperature distribution of the panel in advance and attach the temperature sensors to the two places, the place where the temperature hardly rises and the place where the temperature hardly falls. Various monitors are possible. Furthermore, if you know the temperature settings and time settings of the heater and the panel temperature profile, including the differences between the panels, you can adjust the heater temperature without installing a temperature sensor for each panel and monitoring the temperature. Temperature control is possible only by controlling the vessel. The temperature distribution of the liquid crystal panel is slightly improved by covering the side of the liquid crystal panel which is not in contact with the surface heater with a heat equalizing material such as silicone rubber. Also, as a temperature control means, it is considered that the constant temperature layer is more effective than the surface heater, but the productivity is higher, but there are many experimental factors such as temperature monitoring and visual confirmation of the phase transition process. Therefore, the surface heater was used.

Using this apparatus, the liquid crystal 2 is heated until it becomes the Ch phase, and then the liquid crystal 2 is changed from the cholesteric (Ch) phase to the chiral smectic C (Sm-C) in the temperature decreasing process.
^* ) A DC voltage of 5 V was applied during the phase. The application of the DC voltage was performed via the drive controller 52 and the drivers 7 and 8. That is, reference numeral B in FIG.
_As indicated by reference numeral ₁ , the gate line G _i is line-sequentially scanned by the scanning signal driver 7 as in the case of driving for normal display, and the desired DC voltage is applied from the information signal driver 8 to the source electrode 47 of the TFT 4. Was applied. At this time, for example, in the case of an information signal driver compatible with dot inversion drive,
Due to its configuration, it is difficult to output a desired DC voltage from all output pins, so that 0 V is output and the desired DC voltage is applied to the liquid crystal pixels by adjusting the potential on the counter substrate side of the liquid crystal panel. Good. Further, in the case of an information signal driver compatible with line inversion, it is relatively easy to output a desired DC voltage from all output pins. When line-sequential scanning is performed on the gate line G _i , a feedthrough voltage is generated, and therefore the voltage applied to the liquid crystal pixel cannot be accurately grasped. However, depending on the specifications of the TFT array of the liquid crystal panel, the feedthrough voltage is 1-2V.
However, the variation between panels is not so large. Further, it has been confirmed that even if an error of about ± 1 V occurs in the voltage applied during the phase transition, a large difference does not occur in the obtained alignment state. The period during which the voltage is applied is from before the lowest temperature portion of the liquid crystal panel falls below the phase transition temperature (t1 in FIG. 11) until the highest temperature portion of the liquid crystal panel falls below the phase transition temperature (t in FIG. 11).
2). The voltage application time was about 10 minutes in the case of a panel having a diagonal length of 10.4 inches, although it varied depending on the size of the liquid crystal panel. By applying the DC voltage for about 10 minutes, the orientation control film is considerably polarized and an anti-electric field is formed in the liquid crystal layer. After the DC voltage was continuously applied for 30 minutes or more, the applied voltage was set to 0 V, and the liquid crystal responded in the opposite direction. That is, since the polarization of the film is almost completed, it is assumed that the polarization of the orientation control film is considerably advanced even after 10 minutes in view of the time constant. In addition, the time taken for the polarization of the alignment control film to differ depending on the individual panel, and in some panels the alignment state obtained at and near the highest temperature part of the liquid crystal panel may be different from the other part. Came out. In other words, the part with the highest temperature and its surroundings are Sm-C * from the Ch phase.
At the time of transition to the phase, the voltage applied to the liquid crystal layer is 0V.
It is presumed that it was in a state close to.

Therefore, before the time t1 in FIG. 11, for 10 minutes or more, a voltage having a polarity opposite to that of the voltage during the alignment treatment (here, −).
Step B ₂ of applying a DC voltage (here, 5 V) in the process of transitioning from the Ch phase to the Sm-C * phase while lowering the temperature in the same manner as the above-mentioned process after providing the pretreatment period B ₁ for applying 5 V). And

As a result, as shown in FIG. 7, the polarization component ΔV generated in the pretreatment period B ₁ causes B ₂ during the alignment treatment.
Further, a large voltage can be applied to the liquid crystal layer, and the entire panel can be uniformly aligned.

Example 2 In this example, a liquid crystal panel having an equivalent circuit shown in FIG. 4 was produced and driven by the method shown in FIG. 8 to change the potential of each part as shown in FIG. Figure 8
FIG. 9 is a timing chart showing a voltage application process for the liquid crystal panel, and FIG. 9 is a diagram showing a relationship between the applied voltage and the voltage of the liquid crystal layer.

The major difference from the driving method of the first embodiment is that
Between the pretreatment period B ₁ and the alignment treatment period B ₂ , a relaxation period B
₁₂ is provided, and the applied voltage at B ₁₂ is kept at 0 V during that period.

According to this embodiment, the maximum value of NodeB-NodeC (the maximum voltage value applied to the liquid crystal) in the alignment treatment period B ₂ can be made appropriate.

Example 3 In this example, a liquid crystal panel having an equivalent circuit shown in FIG. 4 was produced and driven by the method shown in FIG. That is, the gate voltage having a constant potential is continuously applied to each gate line.

As a result, the feedthrough voltage generated when the TFT is turned off does not occur, so that the value of the DC voltage applied during the alignment process can be managed more accurately.

However, when this method is adopted, it is necessary to have a function for setting the outputs of all the gate driver ICs to a level for turning on the TFT gates, and if the TFT gates are kept on under a constant temperature environment, Since the threshold voltage shift occurs, it is necessary to fully consider the characteristics of the TFT array used.

[0055]

According to the present invention, the liquid crystal contains a chiral smectic C (Sm) from a cholesteric (Ch) phase.
A DC voltage is applied at the time of transition to the -C ^* ) phase, but before that, a voltage having a polarity opposite to that of the DC voltage is applied, so that the voltage value applied to the liquid crystal layer is maintained and good. It is possible to obtain various alignment states.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the structure of a liquid crystal panel.

FIG. 2 is a characteristic diagram showing an example of transmittance-voltage characteristics of a chiral smectic liquid crystal.

FIG. 3 is a circuit diagram showing an example of a structure of a liquid crystal panel.

FIG. 4 is an equivalent circuit diagram showing an example of a structure of a liquid crystal panel.

FIG. 5 is a schematic diagram showing an apparatus for heating a liquid crystal panel.

FIG. 6 is a timing chart showing a voltage application process for a liquid crystal panel.

FIG. 7 is a diagram showing a relationship between an applied voltage and a voltage of a liquid crystal layer.

FIG. 8 is a timing chart showing a voltage application process for a liquid crystal panel.

FIG. 9 is a diagram showing a relationship between an applied voltage and a voltage of a liquid crystal layer.

FIG. 10 is a timing chart showing a voltage application process for a liquid crystal panel.

FIG. 11 is a diagram showing a temperature change when the liquid crystal panel is heated and cooled.

FIG. 12 is a diagram for explaining a conventional problem.

[Explanation of symbols]

1a, 1b Substrate 2 Chiral smectic liquid crystal 3a Common electrode (first electrode) 3b Pixel electrode (second electrode) 4 TFT (active element) 6a, 6b Alignment control film 7 Scan signal driver (gate line drive circuit) 8 Information signal driver (Source line drive circuit) G _i (i = 1, ...) Gate line P Liquid crystal panel (liquid crystal element) S _j (j = 1, ...) Source line

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1345 G02F 1/1345 1/141 1/141 F term (reference) 2H088 GA03 GA04 GA17 HA03 HA08 JA14 JA17 MA18 2H090 KA09 KA14 LA04 MA10 MA17 MB14 2H092 GA45 GA60 JA24 JB22 JB31 JB61 NA01 PA02 PA03 QA11 QA13 QA18 4H027 BA06 CD01 CD03 CD05 CM01 CM03 CM05 CT01 CT03 CT05 DE01 DE03 DE05 DF01 DF03 DF05 DJ01 DJ03 DJ05 DL01 DL03 DL05

Claims (3)

[Claims] 1. A step of arranging a pair of substrates with a predetermined gap left therebetween, a step of arranging a chiral smectic liquid crystal in the gap between the pair of substrates, and arranging an alignment control film in contact with the chiral smectic liquid crystal. And a step of disposing the first electrode and the second electrode so as to form a plurality of pixels while sandwiching the chiral smectic liquid crystal, and a DC voltage of one polarity is applied to the liquid crystal. And a second voltage application step of applying a DC voltage of another polarity to the liquid crystal when transitioning from a cholesteric (Ch) phase to a chiral smectic C (Sm-C ^* ) phase. The method for manufacturing a liquid crystal element is characterized in that: 2. A step of arranging an active element in each pixel in a state of being connected to the second electrode, a step of connecting a gate line driving circuit to a gate of the active element, and a source line driving to a source of the active element. A step of connecting a circuit and a step of connecting the circuits before the first voltage applying step, and the first voltage applying step is performed in a state where a constant voltage is continuously applied to all the active elements. The method for manufacturing a liquid crystal element according to claim 1. 3. The step of setting the potential difference between the first electrode and the second electrode to approximately 0 V is performed between the first voltage applying step and the second voltage applying step. Item 3. A method for manufacturing a liquid crystal device according to item 1 or 2.