JP2020052081A - Method for manufacturing ferroelectric liquid crystal cell - Google Patents

Abstract

To provide a method for manufacturing a ferroelectric liquid crystal cell, by which a ferroelectric liquid crystal cell aligned to give a stable black state as a whole can be obtained with a high probability by performing a predetermined alignment treatment on the ferroelectric liquid crystal cell.SOLUTION: The method for manufacturing a ferroelectric liquid crystal cell includes: a substrate bonding step (ST1) of bonding substrates via a sealing material; a liquid crystal filling step (ST2) of filling a space between the substrates with a ferroelectric liquid crystal; a specific environmental treatment step (ST4) of leaving the ferroelectric liquid crystal cell in a predetermined moisture environment for a given time; and an alignment treatment step (ST5) of heating the ferroelectric liquid crystal cell to a temperature where a phase transition to a smectic A phase or an isotropic phase occurs, and applying a predetermined electric field to the ferroelectric liquid crystal cell while gradually cooling the cell from the above temperature.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method of manufacturing a ferroelectric liquid crystal cell having a ferroelectric liquid crystal alignment treatment step.

  2. Description of the Related Art Conventionally, liquid crystal display devices have been used in a wide range of fields, taking advantage of their features of being thin and having low power consumption. In recent years, a liquid crystal display device using a ferroelectric liquid crystal (hereinafter abbreviated as FLC) having characteristics such as a quick response time has been commercialized.

[Description of Basic Structure of Ferroelectric Liquid Crystal Cell: FIG. 10]
FIG. 10 is a sectional view showing a basic structure of a conventional ferroelectric liquid crystal cell used in a liquid crystal display device or the like. As shown in FIG. 10, in the ferroelectric liquid crystal cell 1, a pair of substrates 110 and 120 are bonded to each other via a sealing material 102 including a spherical spacer 101. A small gap between the substrate 110 and the substrate 120 is filled with the FLC 130.

  The substrate 110 is a transparent glass substrate, and a solid transparent electrode 111 is formed on an inner surface thereof, and an organic alignment film 112 is formed thereon. The substrate 120 is a silicon substrate, on which an aluminum electrode 121 patterned for each pixel is formed on the inner surface, and an organic alignment film 122 is formed thereon.

  The liquid crystal molecules (not shown) of the FLC 130 filled between the pair of substrates 110 and 120 are regularly aligned by the organic alignment films 112 and 122, that is, are aligned, that is, are aligned. Although not shown here, a layer structure is formed, and the entire liquid crystal layer exhibits a smectic C phase (SmC phase).

[Explanation of FLC molecular sequence: FIG. 11]
Next, a well-known molecular arrangement of FLC, particularly a molecular arrangement of surface-stabilized ferroelectric liquid crystal (SSFLC) will be described with reference to FIG. 11 in order to understand the present invention. FIG. 11A shows a state in which the FLC is in an isotropic phase (ISO phase), and the ferroelectric liquid crystal molecules 131 (hereinafter, referred to as FLC molecules 131) are oriented in different directions. This ISO phase is, for example, a state at a temperature of + 110 ° C. or higher.

  FIG. 11B shows a state in which the FLC is in a nematic phase (N * phase), and all the FLC molecules 131 are oriented in the direction of the alignment control force (arrow E). This N * phase is, for example, in a state where the temperature is between + 90 ° C. and + 110 ° C.

  FIG. 11C shows a state in which the FLC is in a smectic A phase (SmA phase). In this state, the FLC molecules 131 form a predetermined layer structure, and the FLC molecules 131 in each layer are aligned in the direction of the alignment control force ( It points to arrow E). This SmA phase is, for example, in a state where the temperature is between + 80 ° C. and + 90 ° C.

  FIGS. 11D to 11F show three states in which the FLC is in the smectic C phase (SmC * phase). In this state, the FLC molecules 131 form a predetermined layer structure, and The FLC molecules 131 have a predetermined inclination (tilt angle) with respect to the direction of the alignment control force (arrow E). The SmC * phase is, for example, in a state where the temperature is between -35 ° C and + 80 ° C. Therefore, FLC is usually used in the SmC * phase.

  Here, FIGS. 11D to 11F show differences in the inclination of the FLC molecules 131 in the SmC * phase when no voltage is applied. FIG. 11D shows a case where the inclination of the FLC molecules 131 is on the left side of the drawing with respect to the alignment regulating force direction E, and the appearance of display is black. FIG. 11E shows a case where the tilt of the FLC molecules 131 is a double domain in which the left and right sides are mixed with respect to the alignment regulating force direction E (a black stable portion and a white stable portion are mixed). FIG. 11F shows a case where the inclination of the FLC molecule 131 is rightward in the drawing with respect to the alignment regulating force direction E, and the appearance of display is white stable.

  Here, the preferred orientation direction of the FLC molecules 131 is good in black stability (tilt is left) for display use. The reason for this is that black is more stable because black is less likely to appear in black and less uneven during black display. Therefore, it is a characteristic generally required for a ferroelectric liquid crystal cell to make the orientation direction of the FLC molecules 131 black stable (state shown in FIG. 11D) when no voltage is applied.

[Explanation of basic operation of liquid crystal molecules of FLC: FIG. 12]
Next, the basic operation of the liquid crystal molecules of the FLC will be described with reference to FIG. FIG. 12 schematically shows the operation of the liquid crystal molecules of the ferroelectric liquid crystal cell 1 shown in FIG. As shown in FIG. 12, the ferroelectric liquid crystal cell 1 is filled with the FLC 130 between the polarizing plates 140a and 140b adjusted to cross Nicols.

  Here, the FLC molecule 131 of the FLC 130 is positioned on one of the polarization axis A of the polarizing plate 140a and the polarization axis B of the polarizing plate 140b, in the direction of the long axis of the first stable state of the FLC molecule 131 (arrow C) or The orientation regulating force direction (rubbing direction: arrow E) of the orientation film (not shown) is determined so that one of the molecular long axis directions (arrow D) in the second stable state is substantially parallel. Be placed. In FIG. 12, the polarization axis A of the polarizing plate 140a and the molecular long axis direction (arrow C) in the first stable state are arranged to be substantially parallel.

  Here, the switching of the FLC molecule 131, that is, the transition from one stable state to the other stable state occurs when the value of the drive voltage applied to the FLC becomes equal to or higher than a threshold value. For example, a first stable state (arrow C) is selected when a negative voltage equal to or more than the threshold is applied, and a second stable state (arrow D) is selected when a positive voltage equal to or more than the threshold is applied.

  As a result, when the polarizing plates 140a and 140b are arranged as shown in FIG. 12, the first stable state (arrow C) is black stable (non-transmission state), and the second stable state (arrow D) is white stable (arrow D). Transmission state). By changing the arrangement of the polarizing plates 140a and 140b, white stability (transmission state) in the first stable state and black stability (non-transmission state) in the second stable state can be achieved.

  Here, since the FLC molecules 131 have spontaneous polarization, there is a problem that the alignment direction is likely to be unstable due to the influence of the internal electric field of the liquid crystal cell. If the orientation direction of the FLC molecules 131 becomes unstable, a state of a double domain (see FIG. 11E) in which a black stable portion and a white stable portion are mixed undesirably occurs.

[Explanation of unstable operation of liquid crystal molecules caused by internal electric field: FIG. 13]
Next, the cause of the assumption that the orientation direction of the FLC molecules becomes unstable due to the effect of the internal electric field of the ferroelectric liquid crystal cell 1 will be described with reference to the behavior of ions shown in FIG. FIG. 13A schematically shows a cross section of the ferroelectric liquid crystal cell 1 and shows a state immediately after completion of the ferroelectric liquid crystal cell 1. Note that the basic structure of the ferroelectric liquid crystal cell 1 is the same as that of FIG. 10 described above, and each element is denoted by the same reference numeral.

  As shown in FIG. 13A, in the ferroelectric liquid crystal cell 1, a transparent electrode 111 and an aluminum electrode 121 are formed on opposing surfaces of a pair of substrates 110 and 120, and a gap therebetween is filled with an FLC. . It is presumed that this FLC 130 contains positive ions 141 and negative ions 142 mainly due to moisture. Here, for convenience of explanation, the respective ion amounts of the positive ions 141 and the negative ions 142 are shown as 8 (the eight positive ions 141 and the negative ions 142 are schematically shown).

  On the other hand, in the ferroelectric liquid crystal cell 1, there is an electric field generated by a dissimilar metal due to the transparent electrode 111 and the aluminum electrode 121 facing each other, and this electric field is represented by an internal electric field E1 (shown by an upward arrow located on the left side in the drawing). Called. The magnitude of the internal electric field E1 is defined as E1 = + 10 for convenience.

  Here, when the FLC 130 is filled, it is heated and then gradually cooled. However, the FLC 130 changes from an isotropic phase (ISO phase) in which the liquid crystal molecules lose the alignment regularity, and thereafter, the heating temperature decreases. This causes a phase transition to a smectic C phase (SmC * phase) (see FIG. 11). With this phase transition, the adsorption of ions inside the FLC 130 proceeds.

  That is, due to the internal electric field E1, the positive ions 141 are attracted and adsorbed to the transparent electrode 111 on the substrate 110 side, and the negative ions 142 are attracted and adsorbed to the aluminum electrode 121 on the substrate 120 side. When an alignment film (not shown) is formed on the transparent electrode 111 and the aluminum electrode 121, the positive ions 141 and the negative ions 142 are adsorbed on the alignment films, respectively.

  As a result, an internal electric field is generated inside the ferroelectric liquid crystal cell 1 by the adsorbed ions, and this electric field is referred to as an internal electric field E2 (shown by a downward arrow inside the ferroelectric liquid crystal cell 1 in the drawing). Here, assuming that all the ions are adsorbed, the amounts of the adsorbed positive and negative ions are 8 respectively, so that the value of the internal electric field E2 is set to E2 = −8. That is, the internal electric field E2 is shown as a value equal to the amount of adsorbed ions. The polarity of the internal electric field E2 is negative because the internal electric field E2 is generated in a direction to cancel the internal electric field E1.

As a result, the total internal real electric field ER (indicated by an upward arrow located on the right side in the drawing) inside the ferroelectric liquid crystal cell 1 is:
Actual internal electric field ER = Internal electric field E1 + Internal electric field E2 [Equation 1]
Therefore, the actual internal electric field ER = 10−8 = + 2, and the actual internal electric field ER is a positive electric field.

  Here, the internal electric field E1 is substantially constant because it is determined by the material of the counter electrode. However, the amounts of the positive ions 141 and the negative ions 142 inside the ferroelectric liquid crystal cell 1 change depending on the environment in which the liquid crystal cell is placed, whereby the amount of ions adsorbed on the electrode also changes. Therefore, the value of the internal electric field E2 due to the adsorption of ions changes, and as a result, the actual internal electric field ER also changes.

  FIG. 13B shows the orientation direction of the FLC molecules 131 immediately after the completion of the ferroelectric liquid crystal cell 1 in a commonly used cone shape. Here, the orientation direction of the FLC molecules 131 depends on the polarity of the actual internal electric field ER. That is, if the actual internal electric field ER is a positive electric field, the alignment direction of the FLC molecules 131 is on the right side (white stable) in the drawing with respect to the alignment control force direction (arrow E). If the actual internal electric field ER is a minus electric field, the alignment direction of the FLC molecules 131 is on the left side (black stable) in the drawing with respect to the alignment control force direction (arrow E).

  Here, since the actual internal electric field ER immediately after the completion of the ferroelectric liquid crystal cell 1 is a plus electric field (ER = + 2) as described above, the alignment of the FLC molecules 131 immediately after the completion of the ferroelectric liquid crystal cell 1 is performed. As shown, the direction is assumed to be located slightly to the right (slightly white stable) on the drawing with respect to the orientation regulating force direction (arrow E).

  However, as described above, the preferred orientation direction of the FLC molecules 131 is good black stability (to the left with respect to the orientation regulating force direction (arrow E)) which is good for display use. In a slightly white stable state, it is likely to be in a double domain state (see FIG. 11E) under the influence of the fluctuation of the actual internal electric field ER.

  If the orientation direction of the FLC molecules 131 is in the double domain, display unevenness, that is, a problem such as a decrease in in-plane uniformity (brightness and color) of the display screen occurs when the liquid crystal cell is driven, which is not preferable. As described above, in the conventional ferroelectric liquid crystal cell, the orientation direction of the FLC molecules 131 is unstable due to the influence of the fluctuation of the actual internal electric field ER and the like, and the FLC molecules 131 are likely to be in a double domain, and the display quality is degraded.

[Description of Conventional Orientation Treatment Method: FIGS. 14 and 15]
In order to solve the above-mentioned problem, conventionally, a completed ferroelectric liquid crystal cell is maintained at a temperature at which a phase transition from a smectic A phase to an isotropic phase is performed for a certain period of time. A predetermined alternating electric field is applied to the cell, and in the state where the alternating electric field is applied, the ferroelectric liquid crystal cell is gradually cooled, the temperature is lowered to room temperature, and then the application of the predetermined alternating electric field is canceled. A method has been proposed (for example, see Patent Document 1).

  Hereinafter, a conventional alignment treatment method will be described with reference to FIGS. FIG. 14 is an explanatory view showing a conventional alignment process in which a predetermined alternating electric field is externally applied to a ferroelectric liquid crystal cell. As shown in FIG. 14, a power supply 2 for generating an alternating electric field is electrically connected to a transparent electrode 111 of a substrate 110 of the ferroelectric liquid crystal cell 1 and a pad 123 connected to an aluminum electrode 121 of the substrate 120. Is applied for a predetermined time. The alternating electric field is preferably a sine wave having a predetermined offset voltage.

  FIG. 15 is a graph schematically showing the transition of the heating temperature TX for the ferroelectric liquid crystal cell when the conventional alignment treatment is performed. The horizontal axis represents the elapsed time t, and the vertical axis represents the heating temperature TX. As shown in FIG. 15, first, the heating temperature TX of the completed ferroelectric liquid crystal cell 1 is raised from the normal temperature T0 to a temperature T1 at which the FLC 130 shows a smectic A phase or an isotropic phase, and is maintained for a certain time ( Period t1).

  In this period t1, the alternating electric field shown in FIG. 14 is applied, and after the end of the period t1, the heating temperature TX of the liquid crystal cell is gradually lowered to room temperature T0 while the alternating electric field is applied to the ferroelectric liquid crystal cell 1. (Period t2). When the period t2 ends, the conventional alignment processing ends.

[Explanation of change in orientation direction of FLC molecules by conventional orientation treatment: FIG. 16]
Next, how the alignment direction of the FLC molecules of the ferroelectric liquid crystal cell 1 changes by performing the conventional alignment processing will be described with reference to FIG. FIG. 16A schematically shows a cross section of the ferroelectric liquid crystal cell 1 similarly to FIG. 13A described above, and shows the state of an internal electric field and ions when a conventional alignment treatment is performed. Is shown.

  As shown in FIG. 16A, similarly to FIG. 13A, the value of the internal electric field E1 generated by the dissimilar metal is E1 = + 10, and the internal electric field E2 generated by the adsorption of the positive ions 141 and the negative ions 142. Is set to E2 = −8.

Further, the offset value of the alternating electric field applied from the outside by the alignment process is set as an example, and the externally applied electric field EO = −3 (downward arrow on the left end in the drawing). Thus, the actual internal electric field ER due to the alignment process is
Actual internal electric field ER = Internal electric field E1 + Internal electric field E2 + External applied electric field EO [Equation 2]
ER = 10−8−3 = −1. Therefore, by applying the alternating electric field, the actual internal electric field ER of the ferroelectric liquid crystal cell 1 can be made slightly negative.

  The application of the externally applied electric field EO causes the adsorbed positive ions 141 and negative ions 142 to start floating (separating), and the actual internal electric field ER is estimated to go from a minus electric field to a plus electric field. Since it takes a certain amount of time until the electric field is generated, it is considered that the polarity of the actual internal electric field ER is a minus electric field during most of the alignment process.

  The actual internal electric field ER is a negative electric field, and the heating temperature TX for the ferroelectric liquid crystal cell 1 is raised to a temperature T1 showing a smectic A phase or an isotropic phase, and is gradually lowered to a normal temperature T0 after a certain period of time. (See FIG. 15), the orientation direction of the FLC molecules 131 changes.

  FIG. 16B shows the orientation direction of the FLC molecules 131 after the conventional orientation treatment of the ferroelectric liquid crystal cell 1 is performed. As shown in FIG. 16B, the orientation direction of the FLC molecules 131 is the orientation control force direction (arrow E) since the orientation process (alternating electric field application and heating temperature TX) was performed with the actual internal electric field ER being a minus electric field. ) On the left side of the drawing (slightly black stable). That is, the orientation direction of the FLC molecules 131 is a stable black direction which is preferable for display applications.

JP-A-2017-138463 (page 4, FIG. 1)

  However, the present inventors have performed a conventional alignment process (see FIGS. 14 and 15) on a large number of ferroelectric liquid crystal cells to examine the alignment state of FLC molecules. As a result, the occurrence rate of the ferroelectric liquid crystal cell in which the entire surface of the ferroelectric liquid crystal cell becomes black stable alignment (see FIG. 11D) is about 50%, and the required stable alignment direction is obtained. Turned out to be insufficient.

  It is considered that this is because the conventional alignment process can only slightly reduce the actual internal electric field ER to a negative electric field, but is not enough to ensure that the tilt of the FLC molecules 131 is on the black stable side (FIG. 16). (B)).

  An object of the present invention is to solve the above-mentioned problems and to perform a predetermined alignment treatment on a ferroelectric liquid crystal cell, thereby obtaining a ferroelectric liquid crystal cell having a black stable alignment over the entire surface with a high probability. To provide a method for manufacturing a liquid crystal cell.

  In order to solve the above problems, a method for manufacturing a ferroelectric liquid crystal cell of the present invention employs the following method.

  The method of manufacturing a ferroelectric liquid crystal cell according to the present invention includes the steps of: placing a ferroelectric liquid crystal cell filled with ferroelectric liquid crystal between a pair of substrates bonded to each other via a sealing material in a predetermined humidity environment for a predetermined time; An environmental treatment step and an alignment treatment in which the ferroelectric liquid crystal cell is heated to a temperature at which a phase transition from a smectic A phase to an isotropic phase is applied, and a predetermined electric field is applied to the ferroelectric liquid crystal cell while gradually cooling from the temperature. And a step.

  According to the method of manufacturing a ferroelectric liquid crystal cell of the present invention, a large number of ions can be accumulated inside the ferroelectric liquid crystal cell in a specific environment processing step in which the ferroelectric liquid crystal cell is placed in a predetermined humidity environment for a certain period of time. The ions accumulated inside are adsorbed on the electrodes according to the magnitude of the internal electric field generated between the electrodes by the dissimilar metal of the ferroelectric liquid crystal cell. The internal electric field generated by the adsorbed ions and the internal electric field generated by the dissimilar metal are balanced, and the total internal electric field (actual internal electric field) of the ferroelectric liquid crystal cell becomes substantially zero. As a result, the actual internal electric field can be almost certainly changed to the required polarity (negative electric field) by heating in the alignment treatment step and application of the predetermined electric field, and the alignment direction of the liquid crystal molecules is changed to the required direction (black). Stable).

  Further, the specific environment processing step may be performed before the orientation processing step.

  As a result, the ions inside the ferroelectric liquid crystal cell are saturated by the specific environment processing step as a pre-processing, and then the alignment processing step is performed, thereby reliably changing the actual internal electric field to the required polarity. Becomes possible.

  Further, the specific environment processing step may be performed simultaneously with the orientation processing step.

  By performing the specific environment processing step and the orientation processing step at the same time, the manufacturing process can be simplified and the number of manufacturing steps can be reduced.

  Further, the humidity of the humidity environment may be 60% or more.

  Thus, by controlling the humidity in the specific environmental treatment step to 60% or more, it becomes possible to reliably collect many ions inside the ferroelectric liquid crystal cell.

  Further, in the specific environment processing step, the ferroelectric liquid crystal cell is placed in a predetermined high-temperature environment for a predetermined time.

  Thus, as a specific environment processing step, by placing the ferroelectric liquid crystal cell in a predetermined high-temperature environment, accumulation of many ions inside the ferroelectric liquid crystal cell can be promoted.

  Further, the temperature of the high-temperature environment may be 40 ° C. or higher.

  Thus, by controlling the temperature of the specific environmental processing step to 40 ° C. or more, it is possible to reliably store many ions inside the ferroelectric liquid crystal cell.

  Further, the strength of the electric field can be characterized by being equal to or higher than a switching electric field threshold at which the liquid crystal molecules of the ferroelectric liquid crystal switch from one stable state to the other stable state.

  Thereby, the alignment direction of the liquid crystal molecules can be surely aligned with the required direction.

  Further, the strength of the electric field can be characterized by being equal to or higher than the switching electric field threshold at a temperature at which the ferroelectric liquid crystal cell undergoes a phase transition from the smectic A phase to the smectic C phase.

  Thereby, the alignment direction of the liquid crystal molecules can be more reliably aligned with the required direction.

  Also, the strength of the electric field may be substantially equal to the switching electric field threshold.

  Thereby, the alignment direction of the liquid crystal molecules can be more reliably aligned with the required direction.

  Further, it is characterized in that the intensity of the electric field is changed so as to follow a change in the threshold value of the switching electric field.

  Thereby, the alignment direction of the liquid crystal molecules can be more reliably aligned with the required direction.

  In addition, the strength of the electric field can be characterized in that it is smaller than an alignment breakdown electric field threshold at which a prescribed alignment state of the liquid crystal molecules of the ferroelectric liquid crystal is broken.

  Thereby, the alignment direction of the liquid crystal molecules can be surely aligned with the required direction.

  Further, it is characterized in that the intensity of the electric field is changed so as to follow a change in the threshold voltage of the alignment breakdown electric field.

  Thereby, the alignment direction of the liquid crystal molecules can be more reliably aligned with the required direction.

  As described above, according to the present invention, a large number of ions can be accumulated and saturated inside the ferroelectric liquid crystal cell by the specific environmental treatment step of placing the ferroelectric liquid crystal cell in a predetermined humidity environment for a certain period of time. These ions are adsorbed on the electrodes according to the magnitude of the internal electric field generated between the electrodes by the dissimilar metal of the ferroelectric liquid crystal cell. The internal electric field generated by the adsorbed ions and the internal electric field generated by the dissimilar metal are balanced, and the total internal electric field (actual internal electric field) of the ferroelectric liquid crystal cell becomes substantially zero. As a result, the actual internal electric field can be almost certainly changed to the required polarity (negative electric field) by heating in the alignment treatment step and application of the predetermined electric field, and the ferroelectric liquid crystal becomes black stable alignment on the entire surface. It is possible to provide a method for manufacturing a ferroelectric liquid crystal cell capable of obtaining a cell with a high probability.

4 is a flowchart according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a substrate bonding step and a liquid crystal filling step according to the first embodiment of the present invention. FIG. 2 is a top view and a cross-sectional view of a completed ferroelectric liquid crystal cell according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a circuit board mounting process of the ferroelectric liquid crystal cell according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a specific environment processing step of the first embodiment of the present invention. FIG. 3 is an explanatory diagram showing an internal state of a ferroelectric liquid crystal cell and an orientation direction of FLC molecules in a specific environment processing step of the first embodiment of the present invention. FIG. 2 is an explanatory diagram showing an internal state of a ferroelectric liquid crystal cell and an alignment direction of FLC molecules by an alignment treatment step according to the first embodiment of the present invention. 6 is a flowchart according to a second embodiment of the present invention. It is a graph which shows transition of heating, an alternating electric field, and humidification in a specific environment processing process and an orientation processing process of a 2nd embodiment of the present invention. FIG. 9 is a cross-sectional view illustrating a basic structure of a conventional ferroelectric liquid crystal cell. FIG. 3 is an explanatory diagram of a phase and an alignment state of ferroelectric liquid crystal molecules. FIG. 4 is an explanatory diagram showing an operation of a ferroelectric liquid crystal molecule. It is explanatory drawing which shows the internal state immediately after completion of the conventional ferroelectric liquid crystal cell, and the orientation direction of FLC molecule. FIG. 9 is an explanatory diagram illustrating application of an alternating electric field by a conventional ferroelectric liquid crystal cell alignment process. 6 is a graph illustrating a transition of a heating temperature in a conventional ferroelectric liquid crystal cell alignment process. It is explanatory drawing which shows the internal state by the orientation process of the conventional ferroelectric liquid crystal cell, and the orientation direction of FLC molecule.

  The present inventors have studied an alignment treatment method that can increase the probability that the entire surface of a liquid crystal cell becomes black stable alignment. As a result, it was presumed that increasing the amount of ions inside the ferroelectric liquid crystal cell was effective, and the production method of the present invention was obtained.

  Hereinafter, preferred first and second embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or corresponding elements have the same reference characters allotted, and overlapping description will be omitted. The scales and the like of the drawings are appropriately changed for the sake of explanation, and some parts are schematically shown for easy understanding of the structure.

[Features of each embodiment]
The first embodiment is a manufacturing method in which a specific environment processing step is performed before an alignment processing step. The second embodiment is a manufacturing method in which a specific environment processing step and an alignment processing step are performed simultaneously.

[First Embodiment]
[Explanation of Flow of Manufacturing Method According to First Embodiment: FIG. 1]
The flow of the method for manufacturing the ferroelectric liquid crystal cell according to the first embodiment will be described with reference to FIG. As shown in FIG. 1, in the manufacture of a ferroelectric liquid crystal cell, first, a substrate bonding step of bonding a pair of substrates composed of a glass substrate and a silicon substrate via a sealing material is performed (step ST1).

  Next, a liquid crystal filling step of filling the gap between the bonded substrates with FLC is performed (step ST2).

  Next, a circuit board mounting step of fixing the circuit board to the silicon substrate is performed to complete a ferroelectric liquid crystal module (hereinafter abbreviated as FLC module) including a ferroelectric liquid crystal cell and a circuit board (step ST3). .

  Next, a specific environment processing step of placing the FLC module including the ferroelectric liquid crystal cell and the circuit board in a predetermined humidity environment and a predetermined high temperature environment for a predetermined time is performed (step ST4). This specific environmental treatment step aims to store a large number of ions inside the ferroelectric liquid crystal cell.

  Next, an FLC module including a ferroelectric liquid crystal cell and a circuit board is heated at a predetermined temperature, and an alignment processing step of applying a predetermined alternating electric field to the ferroelectric liquid crystal cell is performed (step ST5). In this alignment processing step (ST5), the same processing as the above-described conventional alignment processing (see FIGS. 14 and 15) is performed.

  By performing step ST5, the manufacturing process of the ferroelectric liquid crystal cell is completed, and the FLC module including the ferroelectric liquid crystal cell and the circuit board is completed. This alignment treatment step (ST5) aims at stabilizing the alignment direction of FLC molecules of the ferroelectric liquid crystal cell in black.

[Detailed description of substrate bonding step (ST1) and liquid crystal filling step (ST2): FIG. 2]
Next, the details of the substrate bonding step (ST1) and the liquid crystal filling step (ST2) will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating each manufacturing process of the ferroelectric liquid crystal cell according to the first embodiment. As shown in FIG. 2A, in a substrate bonding step (ST1), a sealing material 102 is applied to one of the opposing surfaces of a glass substrate 110 and a silicon substrate 120, which are a pair of substrates, and the other is applied. Attach the substrates. As a result, an empty ferroelectric liquid crystal cell in which the depletion 105 is formed in the gap between the glass substrate 110 and the silicon substrate 120 is created.

  Next, the process proceeds to a liquid crystal filling step (ST2). As shown in FIG. 2A, an appropriate amount of FLC 130 is applied to the vicinity of the liquid crystal injection opening (liquid crystal injection port) 103 provided in a part of the sealing material 102. Then, the entire empty cell is exposed to a vacuum pressure in a vacuum chamber (not shown) to bring the depletion 105 into a vacuum state.

  Subsequently, as shown in FIG. 2 (b), the entire empty cell is heated to increase the fluidity of the FLC 130, and the FLC 130 is made to penetrate into the depletion 105 to some extent by capillary action. The liquid crystal is continuously injected by utilizing the pressure difference between the inside and the outside of the empty cell by exposure, and the depletion 105 is filled with the FLC 130.

  By heating at the time of filling the FLC 130, the FLC 130 is heated to a temperature at which the liquid crystal molecules become an isotropic phase (ISO phase: see FIG. 11A) in which the alignment regularity is lost. As a result, a phase transition is sequentially performed from an isotropic phase (ISO phase) to a target smectic C phase (SmC phase: see FIG. 11D) through a nematic phase (N phase) and a smectic A phase (SmA phase). I will do it.

  Next, as shown in FIG. 2C, after the filling of the FLC 130 is completed, the heating temperature of the ferroelectric liquid crystal cell is gradually lowered. As a result, the filled FLC 130 decreases in fluidity in the SmC phase alignment state and is fixed inside the liquid crystal cell. Then, after cleaning the excess liquid crystal material attached around the liquid crystal injection port 103, a sealing material 104 is applied near the liquid crystal injection port 103 and cured, thereby completing the ferroelectric liquid crystal cell 100.

[Description of structure of ferroelectric liquid crystal cell: FIG. 3]
Next, a detailed structure of the completed ferroelectric liquid crystal cell 100 of the first embodiment will be described with reference to FIG. The ferroelectric liquid crystal cell 100 has the same basic structure as the above-described conventional ferroelectric liquid crystal cell 1 (see FIG. 10). The part is omitted.

  3A is a top view of the ferroelectric liquid crystal cell 100, and FIG. 3B is a cross-sectional view taken along a cutting line HH ′ in FIG. 3A. As shown in FIG. 3, in the ferroelectric liquid crystal cell 100, a pair of substrates, a glass substrate 110 and a silicon substrate 120 (hereinafter, abbreviated as the substrate 110 and the substrate 120) are disposed via a sealing material 102 including a spacer 101. FLCs 130 are filled with each other, and the narrow gaps between the substrates formed thereby are filled.

  Inside the substrate 110, a transparent electrode 111 and an organic alignment film 112 are formed. On the inside of the substrate 120, an aluminum electrode 121 and an organic alignment film 122 patterned for each pixel are formed.

  The FLC 130 is filled from the liquid crystal injection port 103 and sealed with the sealing material 104. The sealing material 102 is formed on the inner peripheral portions of the substrates 110 and 120, and the FLC 130 is filled in a region surrounded by the sealing material 102. An area (enclosed by a broken line) filled with the FLC 130 becomes an operation area 106 of the FLC 130. Although the aluminum electrode 121 patterned for each pixel can be seen from the operation area 106 shown in FIG. 3A, the illustration is omitted here.

  A plurality of pads 123 are provided side by side on the right end of the substrate 120 in the drawing. These pads 123 function as electrical connection points for inputting power and signals from a circuit board described later. Although not shown, a drive circuit and the like for driving the FLC 130 are formed inside the substrate 120.

[Description of Circuit Board Mounting Step (ST3): FIG. 4]
Next, a circuit board mounting step (ST3) of mounting a circuit board on the completed ferroelectric liquid crystal cell 100 to form an FLC module will be described with reference to FIG. FIG. 4A shows a bonding step in which the completed ferroelectric liquid crystal cell 100 is fixed to a circuit board 150. That is, the back surface 120a of the substrate 120 of the ferroelectric liquid crystal cell 100 and the upper surface 150a of the circuit board 150 are faced to each other and bonded by an adhesive or the like (not shown). Fix in place.

  FIG. 4B shows a bonding step in which the electrodes 151 of the circuit board 150 and the pads 123 on the ferroelectric liquid crystal cell 100 side are connected by a plurality of fine metal wires 152, and the circuit board 150 and the ferroelectric liquid crystal cell are connected. 100 are electrically connected to complete the FLC module 200.

  On the back surface of the circuit board 150, a ROM 160 for storing driving conditions of the ferroelectric liquid crystal cell 100 and the like, and a connector 161 for externally inputting a power supply and a driving signal are mounted. Note that an LED or other electronic component serving as a light source of the ferroelectric liquid crystal cell 100 is also mounted on the circuit board 150, but is not shown here. As described above, the ferroelectric liquid crystal cell 100 is completed as the FLC module 200 by mounting the circuit board 150, and operates by inputting a power supply, a drive signal, and the like from the outside via the connector 161.

[Description of Specific Environment Processing Step (ST4): FIG. 5]
Next, a specific environment processing step (ST4) which is a feature of the present invention performed on the ferroelectric liquid crystal cell 100 will be described with reference to FIG. As described above, the ferroelectric liquid crystal cell 100 is completed as the FLC module 200 with the circuit board 150 mounted thereon. Therefore, the specific environment processing step (ST4) and the alignment processing step (ST5) described below This is performed on the module 200.

  As shown in FIG. 5, the FLC module 200 including the ferroelectric liquid crystal cell 100 and the circuit board 150 is placed in a constant temperature / humidity chamber 300 and placed in a predetermined humidity environment and a predetermined high temperature environment for a predetermined time. The humidity of the predetermined humidity environment is 60% or more, and preferably about 90%. Further, the temperature of the predetermined high-temperature environment is 40 ° C. or higher, and preferably about 60 ° C. An appropriate time is selected as the certain time according to the humidity and the temperature. When the humidity is about 90% and the temperature is about 60 ° C., it is preferably about 20 hours.

  After a certain period of time has passed in the constant temperature and humidity chamber 300, the FLC module 200 is removed from the chamber and returned to the normal temperature and normal humidity environment. The high temperature of about 60 ° C. together with the high humidity of about 90% promotes the accumulation of many ions inside the ferroelectric liquid crystal cell 100. The environment may be at room temperature.

[Explanation of change in orientation direction of FLC molecules in specific environment treatment step (ST4): FIG. 6]
Next, the change in the amount of ions and the change in the internal electric field inside the ferroelectric liquid crystal cell 100 caused by the above-described specific environment processing step (ST4) and the resulting change in the orientation direction of the FLC molecules will be described with reference to FIG. Will be explained. FIG. 6A schematically shows a part of a cross section of the ferroelectric liquid crystal cell 100, and the same reference numerals as in FIG. The state of the ions and the internal electric field immediately after the liquid crystal filling step (ST2) and the orientation direction of the FLC molecules 131 are the same as those in FIG.

As shown in FIG. 6A, in a ferroelectric liquid crystal cell 100, a transparent electrode 111 and an aluminum electrode 121 are formed on opposing surfaces of a pair of substrates 110 and 120, and a gap between them is filled with an FLC 130. . Here, when the ferroelectric liquid crystal cell 100 is placed in an environment having a humidity of about 90% and a temperature of about 60 ° C. for a certain period of time in the specific environment processing step (ST4), moisture enters the liquid crystal cell and becomes positive ions 141 It is assumed that the amount of the negative ions 142 increases. The water content is
It penetrates from the inside and the interface of each element (alignment film etc.) constituting the liquid crystal cell and enters the inside of the liquid crystal cell.

  In the example illustrated in FIG. 6A, it is assumed that the positive ions 141 and the negative ions 142 in the FLC 130 increase and the amount of ions becomes 12 or more, respectively (the 12 positive ions 141 and the negative ions 142 Schematically illustrated).

  Here, it is assumed that the internal electric field E1 generated by the dissimilar metal due to the opposing transparent electrode 111 and aluminum electrode 121 is E1 = + 10 as described above. It is presumed that, due to the internal electric field E1, the positive ions 141 having an ion amount of 10 are adsorbed on the transparent electrode 111, and the negative ions 142 having an ion amount of 10 are also adsorbed on the aluminum electrode 121.

  Then, since the amount of the positive ion 141 and the amount of the negative ion 142 are assumed to be 12, it is presumed that each of the remaining ion amounts 2 after subtracting the adsorbed ion amount 10 floats in the FLC 130. That is, by performing the specific environment processing step (ST4), the amount of ions in the FLC 130 increases, and the ions are saturated with respect to the internal electric field E1.

  Therefore, even if the amount of ions in the FLC 130 further increases, the adsorbed ions are saturated with respect to the internal electric field E1, so that only the floating ions increase and the amount of the adsorbed ions hardly increases.

  Due to the adsorbed ions, an internal electric field E2 (indicated by a downward arrow inside the ferroelectric liquid crystal cell in the drawing) is generated inside the ferroelectric liquid crystal cell 100. Here, since the amount of adsorbed ions is set to 10, the internal electric field E2 generated in a direction to cancel the internal electric field E1 by the adsorbed ions is E2 = −10. As a result, the actual internal electric field ER of the ferroelectric liquid crystal cell 100 is obtained from the above-described equation 1, that is, the actual internal electric field ER = the internal electric field E1 + the internal electric field E2 = 10−10 = 0.

  As described above, by performing the specific environment processing step (ST4), the number of ions inside the ferroelectric liquid crystal cell 100 increases, and the amount of ions adsorbed on the electrode is saturated with respect to the internal electric field E1. Thus, it can be estimated that the internal electric field E2 due to the adsorbed ions and the internal electric field E1 due to the dissimilar metal cancel each other out, and that the total internal electric field ER inside the ferroelectric liquid crystal cell 100 is balanced so as to be substantially zero. That is, by performing the specific environment processing step (ST4), the internal ions of the ferroelectric liquid crystal cell 100 can be saturated with respect to the internal electric field E1, and the actual internal electric field ER can be made substantially zero.

  FIG. 6B shows the orientation direction of the FLC molecules 131 of the ferroelectric liquid crystal cell 100 after the execution of the specific environment processing step (ST4). As shown in FIG. 6B, the orientation direction of the FLC molecules 131 is the same as the direction of the alignment regulating force (arrow E) (between white stable and black stable) since the actual internal electric field ER is almost zero. It is located in.

[Explanation of change in alignment direction of FLC molecules in alignment processing step (ST5): FIG. 7]
Next, a change in the amount of ions and a change in the internal electric field inside the ferroelectric liquid crystal cell 100 caused by the alignment processing step (ST5), and a change in the alignment direction of the FLC molecules resulting therefrom will be described with reference to FIG. . FIG. 7A schematically shows a part of the cross section of the ferroelectric liquid crystal cell 100 as in FIG. 6A, and each element is given the same number as in FIG. 3 described above. .

  As shown in FIG. 7A, in the ferroelectric liquid crystal cell 100, an internal electric field E1 generated by a dissimilar metal of the transparent electrode 111 and the aluminum electrode 121, and an internal electric field E1 generated by adsorption of the positive ions 141 and the negative ions 142. An electric field E2 exists. The offset value of the alternating electric field applied from the outside in the alignment processing step (ST5) is defined as an externally applied electric field EO (downward arrow on the left end in the drawing).

  Here, the internal electric field E1 is set to +10, and the external applied electric field EO in the alignment processing step (ST5) is set to EO = -3 as an example. At the beginning of the alignment treatment step (ST5), the positive ions 141 and the negative ions 142 are assumed to have an ion amount of 10 adsorbed on each electrode as described above (see FIG. 6A). ), The internal electric field E2 = −10.

  However, due to the externally applied electric field EO = −3 in the alignment treatment step (ST5), as time elapses, only 3 ions are removed and the adsorbed ions float, and the total amount of the floating ions is the amount of the ions floating from the beginning. Together with the quantity 2, the ion quantity becomes 5 respectively. As a result, the adsorbed ions of the positive ions 141 and the negative ions 142 decrease from the initial ion amount of 10 to 7 respectively, and the internal electric field E2 generated by the adsorbed ions is reduced at the end of the alignment process (ST5). -7 (FIG. 7A).

  As a result, the actual internal electric field ER of the ferroelectric liquid crystal cell 100 becomes, at the beginning of the alignment processing step (ST5), the actual internal electric field ER = 10−10−3 = −3 according to the above-described equation (2). Also, at the end of the alignment processing step (ST5), the internal electric field E2 = -7 as described above, so that the actual internal electric field ER = 10-7-3 = 0.

  As described above, in the period of the alignment process (ST5), the actual internal electric field ER changes from −3 to finally zero. However, since it takes some time for the actual internal electric field ER to change from −3 to almost zero, the polarity of the actual internal electric field ER is sufficiently negative during most of the alignment process (ST5). Can be inferred.

  The actual internal electric field ER is a minus electric field, and the heating temperature TX to the ferroelectric liquid crystal cell 100 is raised to a temperature T1 showing a smectic A phase or an isotropic phase, and is gradually lowered to a normal temperature T0 after a certain period of time. (See FIG. 15), the layer structure of the FLC molecules 131 is reconstructed, and the orientation direction changes.

  FIG. 7B shows the orientation direction of the FLC molecules 131 of the ferroelectric liquid crystal cell 100 after the execution of the alignment treatment step (ST5). As shown in FIG. 7B, the orientation direction of the FLC molecules 131 is such that the actual internal electric field ER is sufficiently negative to perform the orientation treatment (heating temperature TX and alternating electric field application). It is greatly inclined with respect to the arrow E) and comes to the left side (black stable) on the drawing. As a result, the orientation direction of the FLC molecules 131 does not become a double domain, and black stable for display use is obtained.

  The present inventors have made a large number of prototypes of ferroelectric liquid crystal cells 100 manufactured by the manufacturing method according to the first embodiment, and have inspected them. As a result, a ferroelectric liquid crystal cell having a black stable alignment over the entire surface has a high probability (in some cases). Was obtained with a probability of almost 100%).

  As described above, according to the first embodiment of the present invention, the ferroelectric liquid crystal cell 100 is subjected to the specific environment processing step (ST4) in which the ferroelectric liquid crystal cell 100 is placed in the environment of the predetermined humidity and temperature for a certain period of time. Many ions accumulate inside, and the ions adsorbed according to the internal electric field E1 become saturated. Thus, the internal electric field E2 due to the adsorbed ions and the internal electric field E1 due to the dissimilar metal are balanced, and the total actual internal electric field ER of the ferroelectric liquid crystal cell 100 becomes substantially zero.

  Further, by the alignment processing step (ST5) performed after the specific environment processing step (ST4), the alignment direction of the FLC molecules 131 of the ferroelectric liquid crystal cell 100 becomes black stable as required.

  Thus, a method of manufacturing a ferroelectric liquid crystal cell in which a ferroelectric liquid crystal cell in which the entire surface becomes black stable alignment can be obtained with a high probability can be realized. As a result, when driving the ferroelectric liquid crystal cell, there is no display unevenness, that is, a decrease in in-plane uniformity (brightness and color) of the display screen and the like, and a high quality and stable operation of the ferroelectric liquid crystal cell is realized. Can be provided.

  The following can be said about the externally applied electric field EO which is the offset value of the alternating electric field applied from the outside in the alignment processing step (ST5). First, in order to ensure that the FLC molecules 131 are in a black stable state, the intensity of the externally applied electric field EO is determined by a threshold value at which the FLC molecules 131 switch from a white stable state to a black stable state (hereinafter, a switching electric field threshold value). ). However, if the intensity of the externally applied electric field EO is too large, the FLC molecules 131 move beyond the specified movable range, thereby destroying the specified orientation state of the FLC molecules 131, which is prevented. In order to do so, it is preferable that the intensity of the externally applied electric field EO is smaller than a threshold value at which the prescribed alignment state of the FLC molecules 131 is destroyed (hereinafter, referred to as an alignment breakdown electric field threshold value). In addition, as the strength of the externally applied electric field EO increases, it becomes easier to remove adsorbed ions, and the actual internal electric field ER tends to change from a negative electric field to a positive electric field (FIG. 7A). The intensity of the externally applied electric field EO is preferably as small as possible (close to zero). In summary, it can be said that it is particularly preferable that the intensity of the externally applied electric field EO is substantially equal to the switching electric field threshold of the FLC molecule 131.

  The switching electric field threshold of the FLC molecule 131 is, for example, an electric field corresponding to a voltage of about 0.2 V, and the alignment breakdown voltage threshold of the FLC molecule 131 is, for example, an electric field corresponding to a voltage of about 3.0 V. These values change according to the configuration of the ferroelectric liquid crystal cell 100 and the environment (temperature, etc.). In particular, the switching electric field threshold of the FLC molecules 131 is likely to change according to the temperature of the ferroelectric liquid crystal cell 100. Specifically, the switching electric field threshold of the FLC molecules 131 tends to decrease as the temperature of the ferroelectric liquid crystal cell 100 increases, and increase as the temperature of the ferroelectric liquid crystal cell 100 decreases. Here, it is preferable that the intensity of the externally applied electric field EO applied to the ferroelectric liquid crystal cell 100 in the alignment processing step (ST5) is always equal to or higher than the switching electric field threshold of the FLC molecules 131. Since the electric field threshold changes in conjunction with the change in the temperature of the ferroelectric liquid crystal cell 100 between T1 and T0 (see FIG. 9), when the strength of the externally applied electric field EO is constant, The intensity of the externally applied electric field EO is not always higher than the switching electric field threshold of the FLC molecules 131.

  To cope with this, for example, it is conceivable to change the intensity of the externally applied electric field EO according to a change in the temperature of the ferroelectric liquid crystal cell 100 (a change in the switching electric field threshold of the FLC molecules 131). Specifically, the switching electric field threshold value of the FLC molecule 131 changes so as to increase as the temperature of the ferroelectric liquid crystal cell 100 decreases from T1 to T0. The intensity of the externally applied electric field EO is changed so as to increase as the temperature of the ferroelectric liquid crystal cell 100 decreases from T1 to T0. At this time, it is ideal that the intensity of the externally applied electric field EO changes while always maintaining a state substantially equal to the switching electric field threshold value of the FLC molecule 131.

  Since the orientation direction of the FLC molecule 131 is stable at the time of the phase transition from the smectic A phase to the smectic C phase (for example, around + 80 ° C.), the intensity of the externally applied electric field EO is set to be equal to or higher than the switching electric field threshold of the FLC molecule 131. Is valid up to that point, or just at that point. Since the orientation direction of the FLC molecules 131 is relatively stable from that point until the temperature decreases to T0 (normal temperature), the intensity of the externally applied electric field EO is not necessarily equal to or greater than the switching electric field threshold of the FLC molecules 131. do not have to. However, since the orientation direction of the FLC molecules 131 may be somewhat unstable until the temperature approaches T0, the intensity of the externally applied electric field EO is reduced until the temperature approaches T0. It is preferable to set the threshold value or more.

  It is preferable that the intensity of the externally applied electric field EO is always smaller than the alignment breakdown electric field threshold of the FLC molecules 131. However, when the alignment breakdown electric field threshold changes according to the temperature of the ferroelectric liquid crystal cell 100, the change is not changed. The intensity of the externally applied electric field EO may be changed so as to follow the following. At this time, it is ideal that the intensity of the externally applied electric field EO changes while maintaining a state where it is always smaller than the alignment breakdown electric field threshold and is always equal to or larger than the switching electric field threshold.

[Second embodiment]
[Explanation of Flow of Manufacturing Method According to Second Embodiment: FIG. 8]
Next, the flow of the method for manufacturing the ferroelectric liquid crystal cell according to the second embodiment will be described with reference to FIG. Steps ST11 to ST13 in the flow shown in FIG. 8 are the same as the above-described flow of the first embodiment (FIG. 1: ST1 to ST3), and a description thereof will be omitted.

  After the end of step ST13 (circuit board mounting step), a specific environment processing step of placing the FLC module including the ferroelectric liquid crystal cell and the circuit board in a predetermined humidity environment for a predetermined time, and heating the ferroelectric liquid crystal cell at a predetermined temperature At the same time, an alignment process for applying a predetermined alternating electric field is performed simultaneously (step ST14). By carrying out this step ST14, the manufacturing process of the ferroelectric liquid crystal cell of the second embodiment is completed, and the FLC module 200 including the ferroelectric liquid crystal cell 100 and the circuit board 150, as in the first embodiment. Is completed.

[Description of Simultaneous Implementation Step (ST14) of Specific Environment Processing Step and Alignment Processing Step: FIG. 9]
Next, step ST14 in which the specific environment processing step and the alignment processing step are performed simultaneously will be described in detail with reference to FIG. Note that FIG. 5, FIG. 6, and FIG. 14 are also referred to. Step ST14 is a step in which the specific environment processing step and the alignment processing step are performed simultaneously, as described above. For this reason, the FLC module 200 including the ferroelectric liquid crystal cell 100 and the circuit board 150 is placed in a thermo-hygrostat 300 (see FIG. 5).

  In the constant temperature / humidity chamber 300, the humidity is controlled for the specific environment processing step, and the temperature is controlled for the orientation processing step. In addition, for the alignment process, an alternating electric field having a predetermined offset voltage is applied to the FLC module 200 for a predetermined time (see FIG. 14).

  FIG. 9 shows the transition of the heating temperature TX for heating the FLC module 200 for the alignment processing step, the application timing of the alternating electric field EX, and the timing of the humidification operation for the specific environment processing step in step ST14. FIG.

  As shown in FIG. 9, the period t0 is a period in which the heating temperature TX is heated from the normal temperature T0 to the temperature T1 at which the FLC indicates the smectic A phase to the isotropic phase in the FLC module 200 as the alignment treatment step. In this period t0, the alternating electric field EX is not applied (OFF).

  Further, in this period t0, a humidifying operation is performed as a specific environmental processing step so as to reach a predetermined humidity (humidifying ON). The predetermined humidity is 60% or more, and preferably about 90%.

  It is estimated that the amount of ions in the FLC 130 increases due to the humidifying operation in the period t0, and the increased ions are adsorbed on the transparent electrode 111 and the aluminum electrode 121 by the internal electric field E1 generated by the dissimilar metal of the electrode (FIG. 6).

  Next, in the period t1, the heating temperature TX is maintained at the temperature T1 at which the FLC 130 shows the smectic A phase to the isotropic phase, and in the next period t2, the heating temperature TX is gradually cooled to the normal temperature T0. In the period t1 and the period t2, the alternating electric field EX is turned on and applied to the ferroelectric liquid crystal cell 100.

  Further, in the periods t1 and t2, it is preferable that the humidifying operation is performed as the specific environment processing step. However, if the humidifying operation is sufficiently performed in the period t0, the humidifying operation in the periods t1 and t2 does not need to be performed. Good. Therefore, the humidification operation in the periods t1 and t2 may be either (ON or OFF).

  As described above, in the second embodiment, in the period t0 of step ST14, the humidifying operation by the specific environment processing step is performed, whereby the ions in the FLC 130 increase as in the first embodiment, Since the internal electric field E1 is saturated and adsorbed, the actual internal electric field ER is estimated to be almost zero (see FIG. 6).

  Further, in the period t1, as the alignment treatment step, the temperature T1 at which the FLC 130 shows the smectic A phase to the isotropic phase is maintained while the alternating electric field EX is being applied. It is gradually cooled to T0.

  As a result, as in the first embodiment, the ferroelectric liquid crystal cell is subjected to the alignment processing step in a state where the actual internal electric field ER is a sufficient negative electric field. A method of manufacturing a ferroelectric liquid crystal cell that can obtain a liquid crystal cell with high probability can be realized. In the second embodiment, since the specific environment processing step and the alignment processing step are performed simultaneously in step ST14, there is an advantage that the manufacturing process can be simplified and the number of manufacturing steps can be reduced. In the second embodiment, the specific environment processing step of step ST4 (see FIG. 1) in the first embodiment can be performed before the specific environment processing step of step ST14. According to this, the amount of ions in the FLC 130 can be reliably increased.

  The timing at which the specific environmental treatment process is performed is not limited to the timing shown in the first embodiment and the second embodiment, and may be another timing. For example, the specific environment processing step can be performed before the circuit board mounting step (see FIGS. 1 and 8).

REFERENCE SIGNS LIST 100 Ferroelectric liquid crystal cell 101 Spacer 102 Sealing material 103 Liquid crystal injection port 104 Sealing material 106 Operating area 110 Glass substrate (substrate)
111 Transparent electrode 112, 122 Organic alignment film 120 Silicon substrate (substrate)
121 Aluminum electrode 123 Pad 130 Ferroelectric liquid crystal (FLC)
131 Ferroelectric liquid crystal molecules (FLC molecules)
140a, 140b Polarizing plate 141 Positive ion 142 Negative ion 150 Circuit board 151 Electrode 152 Wire 160 ROM
161 Connector 200 Ferroelectric liquid crystal module (FLC module)
300 constant temperature and humidity chamber

Claims (12)

A specific environment processing step of placing a ferroelectric liquid crystal cell filled with ferroelectric liquid crystal between a pair of substrates bonded to each other via a sealing material in a predetermined humidity environment for a predetermined time,
Heating the ferroelectric liquid crystal cell to a temperature at which the phase transition from the smectic A phase to the isotropic phase, while gradually cooling from the temperature, an alignment treatment step of applying a predetermined electric field to the ferroelectric liquid crystal cell,
A method for manufacturing a ferroelectric liquid crystal cell, comprising: The specific environment treatment step is performed before the alignment treatment step,
2. The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: The specific environment treatment step is performed simultaneously with the orientation treatment step,
2. The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: The humidity of the humidity environment is 60% or more;
The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: In the specific environment processing step, the ferroelectric liquid crystal cell is placed in a predetermined high-temperature environment for a predetermined time,
The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: The temperature of the high-temperature environment is 40 ° C. or higher;
6. The method for manufacturing a ferroelectric liquid crystal cell according to claim 5, wherein: The strength of the electric field is equal to or higher than a switching electric field threshold at which liquid crystal molecules of the ferroelectric liquid crystal are switched from one stable state to the other.
The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: The strength of the electric field is equal to or higher than the switching electric field threshold at a temperature at which the ferroelectric liquid crystal cell undergoes a phase transition from a smectic A phase to a smectic C phase.
The method for manufacturing a ferroelectric liquid crystal cell according to claim 7, wherein: The strength of the electric field is substantially equal to the switching electric field threshold;
The method for manufacturing a ferroelectric liquid crystal cell according to claim 7 or 8, wherein: Changing the intensity of the electric field to follow a change in the switching electric field threshold,
The method for manufacturing a ferroelectric liquid crystal cell according to claim 7, wherein: The strength of the electric field is smaller than an alignment breakdown electric field threshold at which a prescribed alignment state of the liquid crystal molecules of the ferroelectric liquid crystal is broken.
The method for manufacturing a ferroelectric liquid crystal cell according to claim 1, wherein: The intensity of the electric field is changed so as to follow a change in the alignment breakdown electric field threshold,
The method for manufacturing a ferroelectric liquid crystal cell according to claim 11, wherein:

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