JP2009222835A - Method of manufacturing liquid crystal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress display unevenness by reducing deviation of impurity ions adsorbed to a TFT substrate and an opposite substrate even when rubbing processing performed on alignment layers formed on opposite surfaces of both substrates is uneven. <P>SOLUTION: Thin film layers are formed on the TFT substrate 10 and opposite substrate 20 (S1, S11), and alignment layers 16 and 22 are formed on the thin film layers of both substrates 10 and 20 respectively (S2, S12) and subjected to rubbing processing (S3, S13). Then when a potential difference ΔVcom due to variation in common voltage measured by a liquid crystal device 1 completed in advance has a plus value, the alignment layer 16 formed on the TFT substrate 10 is heat-treated at predetermined temperature for a predetermined time based upon the potential difference ΔVcom (S5). Then both substrates 10 and 20 are stuck together with a seal material 31 interposed, and liquid crystal 32 is sealed in a region sectioned by both substrates 10 and 20 and the seal material (S21). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a liquid crystal device in which an alignment film after an alignment process is subjected to a heating process to reduce a potential difference due to a change in common voltage.

  As is well known, a liquid crystal device is configured by sealing liquid crystal between two substrates, a first substrate and a second substrate made of a glass substrate, a quartz substrate, and the like. For example, switching elements such as thin film transistors (TFTs) and pixel electrodes are arranged in a matrix, a counter electrode is arranged on the second substrate, and the optical characteristics of the liquid crystal layer interposed between the two substrates are measured. An image can be displayed by changing it according to the image signal. In the following, for convenience, the first substrate is referred to as a TFT substrate, and the second substrate is referred to as a counter substrate.

  In addition, the TFT substrate on which the TFT is disposed and the counter substrate disposed to face the TFT substrate are manufactured separately. The TFT substrate and the counter substrate are formed in layers by, for example, a semiconductor thin film, an insulating thin film, or a conductive thin film having a predetermined pattern on a glass or quartz substrate by repeating a film forming process and a photolithography process. Thereafter, an alignment film for aligning liquid crystal molecules along the substrate surface is formed on the surfaces of the TFT substrate and the counter substrate facing each other, that is, the surface in contact with the liquid crystal, and no voltage is applied to the alignment film. An alignment process (rubbing process) is performed to determine the alignment of the liquid crystal molecules.

  Next, after providing a sealing material as an adhesive on the periphery of one substrate, in the vacuum injection method, the TFT substrate and the counter substrate are bonded together via this sealing material, and then provided on a part of the sealing material. Liquid crystal is injected from the notched portion into a region surrounded by both substrates and the sealing material, and finally the notched portion is sealed with a sealing material to complete a liquid crystal device. In addition, in the liquid crystal dropping method (ODF: One Drop Fill), after providing a sealing material as an adhesive on the peripheral edge of one substrate, before bonding the other substrate, the region surrounded by the sealing material Then, a predetermined amount of liquid crystal is dropped, and the other substrate is bonded to the liquid crystal so that the liquid crystal is sealed in a region surrounded by both the substrates and the sealing material, thereby completing the liquid crystal device.

  By the way, an impurity ion such as an uncured component or a cured product is generated from the sealing material or the sealing material. When this impurity ion is mixed into the liquid crystal, the impurity ion is applied to the pixel electrode or the counter electrode. The electric field concentrates on the portion where the impurity ions are adsorbed. As a result, the electric field between the pixel electrode and the counter electrode is disturbed, the luminance difference from other pixels to which no impurity ions are adsorbed increases, and display unevenness occurs.

  In general, a predetermined common voltage (hereinafter referred to as an optimal common voltage) to be applied to the counter electrode at a level where the effective values of the positive image signal and the negative image signal coincide with each other so that a direct current component is not applied to the liquid crystal. Set). However, due to the influence of impurity ions, the effective voltage value actually applied to the liquid crystal capacitance differs between positive polarity writing and negative polarity writing, and the substantial common voltage varies with respect to the optimum common voltage.

  For this reason, a DC component is applied to the liquid crystal capacitor in spite of AC driving, and a burn-in phenomenon occurs, and flickering occurs during positive polarity writing and negative polarity writing. The display quality is significantly reduced.

As a countermeasure, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2001-183683), a protrusion is formed at a notch (injection port) for injecting liquid crystal by a vacuum injection method, and the liquid crystal is passed through this notch. When injecting into the region surrounded by the substrate and the sealing material, this projection slows the flow of liquid crystal, disperses the flow due to the generation of turbulent flow, and uniformly disperses impurity ions mixed in the liquid crystal Thus, a technique is disclosed in which the occurrence of display defects is suppressed and good display quality is obtained.
JP 2001-183683 A

  Incidentally, it is known that there is a difference in the amount of impurity ions adsorbed due to the alignment treatment (rubbing treatment) applied to the alignment films formed on the TFT substrate and the counter substrate, respectively. That is, when the alignment treatment (rubbing treatment) applied to the alignment films on both substrates is non-uniform, a difference occurs in the amount of impurity ions adsorbed between the two substrates, and the potential difference ΔVcom (Vcom shift) is caused by fluctuations in the optimum common voltage. Arise.

  Since the manufacturing process is different between the TFT substrate and the counter substrate, it is difficult to uniformly perform the rubbing treatment applied to the alignment films formed on both substrates, and a certain potential difference ΔVcom is generated. When the potential difference ΔVcom increases, the impurity ion adsorption is accelerated and display unevenness occurs.

  However, in the technique disclosed in the above-described document, turbulent flow is generated when liquid crystal is injected, and impurity ions mixed in the liquid crystal are merely uniformly dispersed. If the alignment treatment applied to the alignment films formed on the opposite substrate is not uniform, a difference occurs in the amount of impurity ions adsorbed on both substrates, and the occurrence of display unevenness cannot be suppressed.

  Further, the technique disclosed in the above-mentioned document can be applied to the vacuum injection method, but cannot be applied to the liquid crystal dropping method, and there is a problem of lack of versatility.

  In view of the above circumstances, the present invention provides an impurity for both substrates even when the alignment treatment (rubbing treatment) applied to the alignment films formed on the opposing surfaces of the first substrate and the second substrate is not uniform. To provide a method of manufacturing a liquid crystal device capable of reducing unevenness in the amount of adsorbed ions, reducing a potential difference due to a change in common voltage, suppressing occurrence of display unevenness, and obtaining good display quality. With the goal.

  In order to achieve the above object, a method of manufacturing a first liquid crystal device according to the present invention includes a thin film forming step of forming a thin film layer on a first substrate and a second substrate, and alignment on the thin film layer of both substrates. An alignment film forming step for forming each film; an alignment treatment step for aligning each alignment film; a heat treatment step for heat-treating one of the alignment films after the alignment treatment; the first substrate; A substrate bonding step in which the two alignment films are bonded to each other through a sealing material, and a liquid crystal sealing step in which liquid crystal is sealed in a region defined by the both substrates and the sealing material. And in the heat treatment step, an alignment film formed on the first substrate and an alignment formed on the second substrate based on a potential difference due to a change in common voltage measured with a completed liquid crystal device Select one of the membrane and heat treatment And wherein the door.

  In such a configuration, one of the alignment film formed on the first substrate and the alignment film formed on the second substrate is based on the potential difference due to the variation of the common voltage measured with the completed liquid crystal device. By selectively performing the heat treatment, the bias of the adsorption amount of the impurity ions mixed in the liquid crystal with respect to the first substrate and the second substrate is reduced, and the first substrate and the second substrate can be reduced. Even if the alignment treatment applied to the alignment film formed on each facing surface is non-uniform, since the potential difference is small, the occurrence of display unevenness can be suppressed and good display quality can be obtained.

  The second liquid crystal device manufacturing method is characterized in that, in the first liquid crystal device manufacturing method, the heat treatment performed in the heat treatment step is performed within a range of 200 to 230 ° C.

  According to experiments, it has been clarified that the potential difference can be reduced by heating the alignment film in the range of 200 to 230 ° C. Therefore, by performing the heat treatment on the alignment film in this temperature range, occurrence of display unevenness can be suppressed and good display quality can be obtained.

  The third liquid crystal device manufacturing method is the first or second liquid crystal device manufacturing method, wherein the thin film layer formed on the first substrate has a pixel electrode and is formed on the second substrate. The thin film layer has a counter electrode, and the heat treatment step heats the alignment film formed on the first substrate when the potential difference is a positive value, and the potential difference is a negative value. In this case, the alignment film formed on the second substrate is heat-treated.

  According to the experiment, when the potential difference is a positive value, the impurity ions are biased and adsorbed to the pixel electrode side formed on the first substrate, and when the potential difference is a negative value, the opposing surface formed on the second substrate. It was clarified that impurity ions are adsorbed unevenly on the electrode side. It was also elucidated that the potential difference is reduced by heat-treating the alignment film of the first substrate when the potential difference is positive, and heat-treating the alignment film of the second substrate when the potential difference is negative. Therefore, when the potential difference is a positive value, the alignment film of the first substrate is heat-treated, and when the potential difference is a negative value, the alignment film of the second substrate is heat-treated, thereby suppressing display unevenness. Good display quality can be obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of the liquid crystal device viewed from the counter substrate side together with the components formed thereon, and FIG. 2 is a liquid crystal device after the assembly process for sealing the liquid crystal by bonding the TFT substrate and the counter substrate together. FIG. 2 is a cross-sectional view taken along line HH ′ of FIG. 1.

  As shown in FIG. 1 and FIG. 2, the liquid crystal device 1 has a transparent TFT substrate 10 as a first substrate and a transparent counter substrate 20 as a second substrate disposed opposite thereto, A seal region provided around the image display region 10 a between the opposing surfaces of both the substrates 10 and 20 is bonded via a seal material 31. Although not shown, polarizing plates (not shown) are disposed on the outer surfaces of both substrates 10 and 20.

  A liquid crystal 32 is sandwiched in a region surrounded by the sealing material 31 between the opposing surfaces of the substrates 10 and 20. In the present embodiment, the liquid crystal 32 is supplied using a known liquid crystal dropping method (ODF). As a method of sealing the liquid crystal 32, in addition to the liquid crystal dropping method, after the substrates 10 and 20 are bonded together via the sealing material 31, the liquid crystal 32 is injected from the injection port formed in the sealing material 31. A vacuum injection method is known in which an injection port is sealed after predetermined injection. In the liquid crystal dropping method (ODF), the liquid crystal 32 is dropped in advance on a region surrounded by the sealing material 31 before the substrates 10 and 20 are bonded together. There is no need to form a notch for injection.

  In addition, vertical conduction members 56 are provided at the four corners of the counter substrate 20, and are electrically connected between the vertical conduction terminals 57 provided on the TFT substrate 10 and the counter electrode 21 provided on the counter substrate 20. Conducted. In addition, a light-shielding peripheral light-shielding film 58 that defines the image display region 10a is provided on the counter substrate 20 side in parallel with the inside of the seal region where the sealing material 31 is disposed. In addition, a data line driving circuit 61 and an external circuit connection terminal 62 are provided along one side of the TFT substrate 10 on the outer side of the sealing area where the sealing material 31 is arranged in the peripheral area extending around the image display area. The scanning line driving circuit 63 is provided along two sides adjacent to the one side. Further, on the remaining side of the TFT substrate 10, a plurality of wirings 64 are provided for electrically connecting the scanning line driving circuits 63 provided on both sides of the image display region 10a. Note that the scanning line driving circuit 63 and the wiring 64 are disposed at positions facing the peripheral light shielding film 58 inside the sealing material 31.

  Further, on the TFT substrate 10, an alignment film 16 is formed on the pixel electrode 9a after the pixel switching TFT, the scanning line, the data line, and the like are formed. On the other hand, the uppermost layer portion of the counter substrate 20 is formed. An alignment film 22 is formed, and a predetermined alignment state is set between the alignment films 16 and 22. The alignment films 16 and 22 are made of an alignment polymer such as polyimide resin, and are formed by being applied by printing or the like, and then subjected to a rubbing process to arrange the alignment of liquid crystal molecules when no voltage is applied.

  Further, a flexible wiring board (FPC) (not shown) is electrically connected to the external circuit connection terminal 62, and an image display is performed based on image information supplied from the flexible board via the external circuit connection terminal 62. An image is displayed in the area 10a.

  In the present embodiment, the potential difference ΔVcom [V], which is the fluctuation value of the optimum common voltage of the first liquid crystal device 1, is examined during the lot production. That is, as shown in FIG. 3A, in the step of sealing the liquid crystal 32 to the liquid crystal 32 sealed between the pixel electrode 9a of the TFT substrate 10 and the counter electrode 21 of the counter substrate 20, A small amount of impurity ions I flowing from the sealing material 31 are mixed. Even if the impurity ions I are mixed in the liquid crystal 32, if the rubbing process is uniformly performed on the alignment films 16 and 22 formed on both the substrates 10 and 20, an alternating voltage as set is applied to both electrodes 9a. , 21, the impurity ions I are not adsorbed on the electrodes 9 a, 21.

  However, when the rubbing process for the alignment films 16 and 22 is not uniform, the balance of the AC voltage applied between the electrodes 9a and 21 is lost, and as shown in FIG. Depending on the nature of the electrode, it is adsorbed biased to any of the electrodes (pixel electrode 9a in the figure). Impurity ions I are biased and adsorbed to any one of the electrodes (pixel electrode 9a in the figure), and when the bias is increased, the liquid crystal 32 is applied even if an AC voltage corresponding to a video signal is applied between the electrodes 9a and 21. Since the applied voltage is affected by the impurity ions I adsorbed on the electrode (pixel electrode 9a in the figure), the orientation of the liquid crystal molecules is controlled by a voltage different from the actual voltage.

  As shown in FIG. 4, according to the experiment, when the impurity ions I are adsorbed unevenly on the TFT substrate 10 side, the measured value of the potential difference ΔVcom becomes positive, and the impurity ions I are adsorbed unevenly on the counter substrate 20 side. Then, the measured value of the potential difference ΔVcom becomes negative. In addition, when the potential difference ΔVcom is a positive value, the alignment film 16 formed on the TFT substrate 10 is heated to improve the uneven adsorption of the impurity ions I. As shown in FIG. ΔVcom falls within a preset positive allowable level. In addition, when the potential difference ΔVcom is a negative value, the alignment film 22 formed on the counter substrate 20 is heated to improve the uneven adsorption of the impurity ions I. As shown in FIG. ΔVcom is set to a preset negative allowable level.

  Further, as shown in FIG. 4, the alignment films 16 and 22 are heated at a temperature of 200 [° C.] or more for 1 hour, so that the potential difference ΔVcom is improved to be within an allowable level. Further, when the heating temperature is 230 [° C.] or more, the potential difference ΔVcom is almost flat. From the above, it is considered that the heating temperature is preferably 200 to 230 [° C.] when the heating time is 1 hour. The heating temperature (200 to 230 [° C.]) is a temperature range that does not cause thermal damage to the substrates 10 and 20.

  Therefore, the potential difference ΔVcom measured in advance by the liquid crystal device 1 and data on how much temperature and time the alignment film 16 or 22 should be heated with respect to the potential difference ΔVcom are acquired in advance through experiments or the like. Thus, when the liquid crystal device 1 is produced in a lot, it is necessary to heat the alignment films 16 and 22 formed on the substrates 10 and 20 only by measuring the potential difference ΔVcom from the first liquid crystal device 1. It can be determined whether or not the heating temperature and the heating time can be uniquely set when the heat treatment is performed.

  For example, as shown in FIG. 4A, when the measured potential difference ΔVcom is +0.14 [V], the potential difference ΔVcom is obtained by heating the alignment film 16 of the TFT substrate 10 at 200 to 230 [° C./1 h]. Can be within the allowable level on the plus side. Further, as shown in FIG. 4B, when the measured potential difference ΔVcom is −0.14 [V], the potential difference ΔVcom is reduced by heating the alignment film 22 of the counter substrate 20 at 200 to 230 [° C./1 h]. Can be within the tolerance level on the minus side.

  The TFT substrate 10 and the counter substrate 20 are manufactured through separate processing steps (pre-processing steps) in the state of large substrates 100 and 200 (see FIG. 7) that can be obtained in plural. When the potential difference ΔVcom measured by the first liquid crystal device 1 is a brass value that is higher than the plus-side allowable level, a heating temperature and a heating time corresponding to the value are set, and the TFT substrate 10 is formed in the pretreatment process. The alignment film 16 formed on the large substrate 100 is heat-treated. On the other hand, when the potential difference ΔVcom measured by the first liquid crystal device 1 is a negative value from the negative allowable level, the heating temperature and the heating time are set according to the values, and the counter substrate 20 is formed in the pretreatment process. The alignment film 22 formed on the large substrate 200 on the other side is subjected to heat treatment. Therefore, when the potential difference ΔVcom is within an allowable level, it is not necessary to heat the alignment films 16 and 22 formed on both large substrates 100 and 200.

  Hereinafter, the manufacturing process of the liquid crystal device 1 will be described. When the lot production is performed, the potential difference ΔVcom of the liquid crystal device 1 completed first is measured, and when the potential difference ΔVcom is a positive value than the plus side allowable level, the liquid crystal device 1 is manufactured according to the flowchart shown in FIG. To do. On the other hand, when the potential difference ΔVcom shows a negative value from the negative allowable level, the liquid crystal device 1 is manufactured according to the flowchart shown in FIG. When the potential difference ΔVcom is within an allowable level, the heat treatment is unnecessary, and the liquid crystal device 1 can be manufactured through a normal manufacturing process, and thus the description thereof is omitted.

  First, a manufacturing process in the case where the potential difference ΔVcom shows a positive value with respect to the positive side allowable level will be described with reference to the flowchart of FIG.

  In the pretreatment process, a multilayer thin film layer that becomes the TFT substrate 10 is formed on the surface of the large-sized substrate 100 (see FIG. 7) in step S1 by being divided into a plurality of parts (thin film forming process).

  Next, in step S2, the alignment film 16 is formed over the entire surface of the large substrate 100 (alignment film forming process), and in step S3, the alignment film 16 is rubbed (alignment process process). ). In step S4, the large substrate 100 is washed to remove dust generated by the rubbing process.

  Then, it progresses to step S5 and heat-processes the alignment film 16 currently formed in the surface of the large sized board | substrate 100 (heat processing process). As shown in FIG. 7, this heat treatment is performed by heating the surface of the alignment film 16 according to a preset heating temperature and heating time using a heating means such as a clean oven. As described above, the heating time and the heating temperature are set based on the potential difference ΔVcom measured from the first liquid crystal device 1.

  Next, the process proceeds to step S6, and the sealing material 31 is applied to the outer periphery of the large substrate 100 and the region to be the TFT substrate 10 by means such as printing. The sealing material 31 is an adhesive, and when the other large substrate 200 described later is bonded, the bonding of the two substrates 100 and 200 is held via the sealing material 31.

  Thus, the pretreatment process for the large substrate 100 having a plurality of TFT substrates 10 is completed. Next, a pretreatment process of another large substrate 200 that becomes the counter substrate 20 will be described.

  In the pretreatment process for manufacturing the large substrate 200, first, in step S11, a thin film layer that is a constituent element of the counter substrate 20 such as the counter electrode 21 is formed on the entire surface of the large substrate 200 by a known film formation process. To form a film (thin film forming step).

  Next, in step S12, the alignment film 22 is formed on the entire opposing surface of the large substrate 200 (alignment film forming process), and in step S13, the alignment film 22 is rubbed (alignment process process). And it progresses to step S14, this large-sized board | substrate 200 is wash | cleaned, and the dust produced by the rubbing process is removed.

  Next, the process proceeds to step S <b> 16, and an appropriate amount of liquid crystal 32 is dropped on the approximate center of the portion that becomes the display area of the counter substrate 20. Thus, the pretreatment process for the large substrate 200 having a plurality of counter substrates 20 is completed.

  Next, a post-processing step is performed. In the post-processing step, first, in step S21, both large substrates 100 and 200 that have completed the pre-processing step are aligned in the vacuum chamber with reference to the alignment marks formed on both the substrates 100 and 200, and in a vacuum environment. (Board bonding process) Then, the liquid crystal 32 spreads in a region surrounded by the sealing material 31 and a liquid crystal layer is formed.

  Next, the large substrates 100 and 200 bonded to each other are taken out from the vacuum chamber. Then, since the area surrounded by the sealing material 31, that is, the liquid crystal layer is kept in a vacuum state, both large substrates 100 and 200 are pressurized by atmospheric pressure, and the liquid crystal 32 is uniformly distributed in the liquid crystal layer. It is sealed in a state (liquid crystal sealing step). Then, after the sealing material 31 is cured to a predetermined level, the large substrates 100 and 200 that are bonded together are divided for each liquid crystal device 1 to complete the post-processing process.

  On the other hand, when the lot production is performed, if the potential difference ΔVcom of the liquid crystal device 1 that has been completed first is more negative than the negative side allowable level, the liquid crystal device 1 is manufactured according to the flowchart shown in FIG.

  The manufacturing process of the large-sized substrate 100 that takes a plurality of TFT substrates 10 in the pretreatment process is performed in the same manner as described above from step S1 to S4, and then the alignment film 16 is not subjected to heat treatment, and step S6 is performed. Then, the sealing material 31 is formed in a predetermined manner, and the pretreatment process of the large substrate 100 is completed.

  Next, a pretreatment process of another large substrate 200 that becomes the counter substrate 20 will be described. In steps S11 to S14 of the pretreatment process for manufacturing the large substrate 200, the same processing as described above is performed, the process proceeds to step S15, and the alignment film 22 formed on the surface of the large substrate 200 is heated (heating process). Process).

  As shown in FIG. 7, in this heat treatment, the surface of the alignment film 22 is heated to a predetermined level using a heating means such as a clean oven. As described above, the time and temperature required for the heat treatment are set based on the potential difference ΔVcom measured from the first liquid crystal device 1.

  Next, the process proceeds to step S16, and an appropriate amount of the liquid crystal 32 is dropped on substantially the center of the portion to be the display area of the counter substrate 20 to complete the pretreatment process of the large substrate 200 having a plurality of counter substrates 20. In addition, since the post-processing process performed by step S21, S22 is as above-mentioned, description is abbreviate | omitted.

  Thus, in this embodiment, even if the rubbing process applied to the alignment films 16 and 22 formed on the opposing surfaces of the TFT substrate 10 and the counter substrate 20 is not uniform, the potential difference ΔVcom measured in advance is measured. On the basis of the above, one of the alignment film 16 formed on the TFT substrate 10 and the alignment film 22 formed on the counter substrate 20 is subjected to predetermined heat treatment so that the electrodes 9a and 21 of both the substrates 10 and 20 are adsorbed. As a result, the potential difference ΔVcom can be kept within the permissible level, so that the occurrence of display unevenness can be suppressed and a good display quality can be obtained.

  The liquid crystal device according to the present invention may be a liquid crystal device having a passive matrix type liquid crystal device or a TFD (thin diode) as a switching element in addition to the TFT active matrix driving type liquid crystal device.

The top view which looked at the liquid crystal device from the counter substrate side with each component formed on it HH 'sectional view of FIG. Explanatory diagram showing the relationship between impurity ions and display unevenness (A) is a characteristic diagram showing the relationship between the heating temperature of the TFT substrate when the potential difference shows a positive value and the change in the potential difference, and (b) shows the heating temperature and potential difference of the counter substrate when the potential difference shows a negative value. Chart showing the relationship with changes Flowchart showing the manufacturing process of the liquid crystal device when the potential difference shows a positive value Flowchart showing the manufacturing process of the liquid crystal device when the potential difference shows a negative value Side view explaining heat treatment of alignment film formed on large substrate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal device, 9a ... Pixel electrode, 10 ... TFT substrate, 16, 22 ... Orientation film, 20 ... Counter substrate, 21 ... Counter electrode, 31 ... Sealing material, 32 ... Liquid crystal, 100, 200 ... Large substrate, I ... Impurity ions, ΔVcom… potential difference

Claims (3)

A thin film forming step of forming a thin film layer on the first substrate and the second substrate;
An alignment film forming step of forming an alignment film on each of the thin film layers of the substrates;
An alignment treatment step of aligning each alignment film;
A heat treatment step of heat-treating one of the alignment films after the alignment treatment;
A substrate bonding step in which the first substrate and the second substrate are bonded to each other with the alignment films facing each other through a sealing material;
A liquid crystal sealing step for sealing liquid crystal in a region defined by the two substrates and the sealing material;
In the heat treatment step, an alignment film formed on the first substrate and an alignment film formed on the second substrate based on a potential difference due to a change in common voltage measured with a completed liquid crystal device. A method for manufacturing a liquid crystal device, characterized in that one is selected and heat-treated. The method for manufacturing a liquid crystal device according to claim 1, wherein the heat treatment performed in the heat treatment step is performed within a range of 200 to 230 ° C. The thin film layer formed on the first substrate has a pixel electrode, and the thin film layer formed on the second substrate has a counter electrode;
The heat treatment step heat-treats the alignment film formed on the first substrate when the potential difference is a positive value, and forms the alignment film formed on the second substrate when the potential difference is a negative value. The method for manufacturing a liquid crystal device according to claim 1, wherein the heat treatment is performed.

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