JP2007127757A - Liquid crystal device, method of manufacturing liquid crystal device, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal device in which a degradation in a liquid crystal caused by a water content is prevented, to provide a method of manufacturing the liquid crystal device, and to provide electronic equipment using the device. <P>SOLUTION: The liquid crystal device has a liquid crystal held between a pair of substrates 10, 20 opposing to each other, wherein inorganic alignment layers 16 (22) are formed on the respective inner surfaces of the substrates 10, 20, and each inorganic alignment layer 16 (22) is subjected to a surface treatment with a plurality of silane coupling agents A, B having different molecular weights. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal device, a method for manufacturing a liquid crystal device, and an electronic apparatus.

  2. Description of the Related Art A liquid crystal device used as a light modulation unit of a projection display device such as a liquid crystal projector has a configuration in which a sealing material is disposed at a peripheral portion between a pair of substrates, and liquid crystal is sealed at a central portion thereof. Electrodes for applying a voltage to the liquid crystal are formed on the inner surfaces of the pair of substrates, and an alignment film for controlling the alignment of liquid crystal molecules when a non-selective voltage is applied is formed on the inner surfaces of these electrodes. With such a configuration, the liquid crystal device modulates light source light based on a change in orientation of liquid crystal molecules between application of a non-selection voltage and application of a selection voltage, thereby producing image light.

  By the way, as the alignment film described above, a film obtained by rubbing the surface of a polymer film made of polyimide or the like to which a side chain alkyl group is added is generally used. The rubbing treatment is to orient the polymer in a predetermined direction by rubbing the surface of the polymer film in a predetermined direction with a roller made of a soft cloth. Due to the intermolecular interaction between the alignment polymer and the liquid crystal molecules, the liquid crystal molecules are arranged along the alignment polymer so that the liquid crystal molecules can be aligned in a predetermined direction when a non-selective voltage is applied. It has become. Further, the side chain alkyl group can give a pretilt to the liquid crystal molecules.

  However, when a liquid crystal device including such an organic alignment film is employed as a light modulation unit of a projector, the alignment film may be gradually decomposed by strong light or heat emitted from a light source. Then, after a long period of use, there is a risk that the liquid crystal molecule alignment control function will be degraded, such as the liquid crystal molecules being unable to align at the desired pretilt angle, and the display quality of the liquid crystal projector will be degraded.

Therefore, the use of an alignment film made of an inorganic material having excellent light resistance and heat resistance has been proposed. As a method for producing such an inorganic alignment film, for example, a silicon oxide (SiO ₂ ) film formed by oblique deposition is used. Film formation is known.
In addition to an alignment film made of such an inorganic material, an alignment film made of a polysilazane film formed under non-aqueous conditions has also been proposed (see, for example, Patent Document 1).
JP-A-5-264998

  However, the alignment film made of the polysilazane film has a problem that if the polysilazane itself contains, for example, chlorine ions, a baking phenomenon tends to occur on the panel. In addition, since such a polysilazane film basically requires a rubbing process, the rubbing process may cause uneven alignment of liquid crystal and cause uneven color.

On the other hand, in the case of an inorganic alignment film formed by oblique deposition or the like, for example, when this inorganic alignment film is made of silicon oxide, a large number of polarized hydroxyl groups exist on the surface. There is a problem that moisture resistance is lowered. That is, this hydroxyl group has activity as a Bronsted acid point, and easily adsorbs or reacts with an impurity present on the alignment film, particularly a compound having a polar group such as water. As a result, there is a problem that this water causes deterioration of the liquid crystal especially by adsorbing water. Another problem is that the hydroxyl group directly reacts with the liquid crystal molecules to cause deterioration of the liquid crystal.
Furthermore, since the inorganic alignment film is generally amorphous and its surface is porous, the adhesion between the inorganic alignment film and the sealing material is low. As a result, there is a problem that the airtightness in these seal portions is lowered, and the moisture resistance as the seal portion is lowered.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal device in which deterioration of liquid crystal due to moisture is prevented, a manufacturing method thereof, and an electronic device using the same. is there.

The liquid crystal device of the present invention is a liquid crystal device in which liquid crystal is sandwiched between a pair of substrates facing each other,
An inorganic alignment film is provided on each inner surface of the pair of substrates;
The inorganic alignment film is characterized by being surface-treated with a plurality of silane coupling materials having different molecular weights.

According to this liquid crystal device, since the inorganic alignment film is used as the alignment film, it is superior in light resistance and heat resistance as compared with the organic alignment film, and therefore excellent in durability.
In addition, since the inorganic alignment film is surface-treated with a plurality of silane coupling materials having different molecular weights, the surface of the inorganic alignment film is mainly made water-repellent by the large molecular weight silane coupling material, and the low molecular weight silane The coupling material mainly makes the inside of the gap between the surface portions of the inorganic alignment film water repellent. Therefore, almost all of the surface layer of the inorganic alignment film is made water-repellent, so that the moisture-proof property is sufficiently improved, thereby reliably preventing the deterioration of the liquid crystal due to moisture (humidity). Thus, stabilization of quality over a long period of time, that is, longer life is achieved.
In addition, since the silane coupling material is effective not only in water repellency but also in improving light resistance, the light resistance of the inorganic alignment film is further improved, which also extends the life.
Furthermore, since the surface treatment is performed with the silane coupling material, the micro pores (holes) on the surface of the porous inorganic alignment film are embedded with the silane coupling material to be dense. Adhesion between the sealing material and the sealing material at the interface between the inorganic alignment film and the sealing material is increased, and the moisture resistance is increased.

In the liquid crystal device, the inorganic alignment film may be made of silicon oxide.
When the inorganic alignment film is made of silicon oxide, a large number of polarized hydroxyl groups exist on the surface. By treating the surface of the inorganic alignment film with a silane coupling material, silane coupling to the hydroxyl group is performed. By the reaction of the material, it is possible to eliminate water adsorption by the hydroxyl group. In addition, since the surface treatment is performed with a plurality of silane coupling materials having different molecular weights, it is difficult to react with all hydroxyl groups due to the steric hindrance only with a high molecular weight silane coupling material. By surface treatment with a coupling material, unreacted hydroxyl groups between hydroxyl groups that have reacted with large silane coupling materials can react with small silane coupling materials to absorb water by the hydroxyl groups. It can be lost.

Further, in the liquid crystal device, the plurality of silane coupling materials have an alkyl group as an organic functional group, and the alkyl group of the silane coupling material having a higher molecular weight is the same as that of the silane coupling material having a lower molecular weight. It is preferable that the number of carbon atoms is larger than that of an alkyl group.
In this way, the silane coupling material having a larger molecular weight exhibits good water repellency and light resistance due to the alkyl group. On the other hand, the lower molecular weight silane coupling material has a shorter alkyl group (has fewer carbon atoms), so that it does not cause steric hindrance to the higher molecular weight silane coupling material, so It reacts easily and becomes attached.

In this liquid crystal device, the silane coupling material having a higher molecular weight among the plurality of silane coupling materials preferably has 18 or more carbon atoms in its alkyl group.
In this way, the silane coupling material having a higher molecular weight will exhibit its water repellency and light resistance even better.

A method for manufacturing a liquid crystal device according to the present invention is a method for manufacturing a liquid crystal device in which liquid crystal is sandwiched between a pair of substrates facing each other.
Forming an inorganic alignment film on each inner surface of the pair of substrates;
And a step of surface-treating the inorganic alignment film with a plurality of silane coupling materials having different molecular weights.

According to this method for manufacturing a liquid crystal device, since the inorganic alignment film is formed as the alignment film, it is superior in light resistance and heat resistance as compared with the organic alignment film, and therefore excellent in durability.
In addition, since the inorganic alignment film is surface-treated with a plurality of silane coupling materials having different molecular weights, the surface of the inorganic alignment film is mainly made water-repellent with a large molecular weight silane coupling material, and a silane coupling with a small molecular weight is performed. Depending on the material, the inside of the gaps of the surface layer of the inorganic alignment film can be made water repellent. Therefore, by making the entire surface layer of the inorganic alignment film water repellent, it is possible to sufficiently improve the moisture resistance, thereby reliably preventing deterioration of the liquid crystal due to moisture (humidity) and quality. Can be stabilized over a long period of time, that is, the life can be extended.

In addition, since the silane coupling material is effective not only in water repellency but also in improving light resistance, the light resistance of the inorganic alignment film can be further improved, and thereby the life can be extended.
Furthermore, by treating the surface with a silane coupling material, micro pores (pores) on the surface of the porous inorganic alignment film can be embedded with the silane coupling material to make the surface dense. It is possible to increase the adhesion between the inorganic alignment film and the sealing material, to increase the airtightness at the seal portion at the interface between the inorganic alignment film and the sealing material, and to improve the moisture resistance.

Moreover, in the manufacturing method of the liquid crystal device, it is preferable that the inorganic alignment film is formed by an oblique deposition method.
In this way, the pre-tilt angle is favorably imparted to the liquid crystal molecules by the inorganic alignment film, and it is not necessary to perform a rubbing treatment or the like on the inorganic alignment film.

In the method for producing a liquid crystal device, the plurality of silane coupling materials are prepared such that the organic functional group is an alkyl group, and the alkyl group of the silane coupling material having a larger molecular weight has a molecular weight. Preparing the plurality of silane coupling materials so that the number of carbon atoms is larger than the alkyl group of the smaller silane coupling material,
In the surface treatment step, the surface treatment is preferably performed first with a silane coupling material having a high molecular weight and then the surface treatment is performed with a silane coupling material having a low molecular weight.
In this way, the surface of the inorganic alignment film can be made water repellent mainly by the silane coupling material having a large molecular weight. At this time, steric hindrance occurs due to the large molecular weight, and it becomes difficult for the silane coupling material to make water repellent, for example, into the gaps in the surface layer of the inorganic alignment film. It becomes difficult to react even with an unreacted hydroxyl group. However, since it is then surface-treated with a silane coupling material having a low molecular weight, it is possible to make water repellent in the gaps on the surface of the inorganic alignment film, and to react with unreacted hydroxyl groups to make it water repellent. become. Therefore, it becomes possible to make the entire surface layer portion of the inorganic alignment film water repellent satisfactorily.

An electronic apparatus according to the present invention includes the liquid crystal device or the liquid crystal device obtained by the manufacturing method.
According to this electronic apparatus, since the liquid crystal device that reliably prevents the deterioration of the liquid crystal due to moisture (humidity) is provided and the life is extended, the electronic apparatus itself is also extended in life. It will be highly reliable.

  The present invention will be described in detail below. First, an embodiment of a liquid crystal device according to the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a TFT array substrate 10 for explaining a schematic configuration of a liquid crystal device according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the liquid crystal device, and FIG. 3 is a plan view of the liquid crystal device. FIG. 4 is an explanatory diagram of the structure, and FIG. 4 is an explanatory diagram of a cross-sectional structure of the liquid crystal device 60, and is a cross-sectional view taken along the line AA ′ in FIG.

  As shown in FIG. 4, the liquid crystal device 60 of the present embodiment has a liquid crystal 50 sandwiched between a pair of substrates 10 and 20 facing each other, and the inorganic alignment film 16 and the inner surfaces of the pair of substrates 10 and 20. 22 is provided. In particular, these inorganic alignment films 16 and 22 are surface-treated with a plurality of silane coupling materials having different molecular weights.

  The schematic configuration of the liquid crystal device 60 will be described. As shown in FIG. 1, an image production region 101 is formed in the center of a TFT array substrate (substrate) 10 that is one of a pair of substrates 10 and 20. . A sealing material 19 is disposed on the peripheral edge of the image production region 101, and thereby the liquid crystal 50 (see FIG. 4) is sealed in the image production region 101. The liquid crystal 50 is formed by directly applying liquid crystal on the TFT array substrate 10, and has a so-called sealing-less structure in which the sealing material 19 is not provided with a liquid crystal inlet. A scanning line driving element 110 that supplies a scanning signal to a scanning line, which will be described later, and a data line driving element 120, which supplies an image signal to a data line, which will be described later, are mounted outside the sealing material 19. A wiring 76 is routed from the driving elements 110 and 120 to the connection terminal 79 at the end of the TFT array substrate 10.

On the other hand, a common electrode 21 (see FIG. 4) is formed on the counter substrate 20 (see FIG. 4) bonded to the TFT array substrate 10. The common electrode 21 is formed over almost the entire image forming region 101, and inter-substrate conducting portions 70 are provided at the four corners. A wiring 78 is routed from the inter-substrate conduction portion 70 to the connection terminal 79.
Then, various signals input from the outside are supplied to the image production region 101 via the connection terminals 79, so that the liquid crystal device is driven.

  In the image production area 101 of the liquid crystal device, as shown in the equivalent circuit diagram of FIG. 2, a plurality of dots are arranged in a matrix to constitute this, and each of these dots has a pixel electrode 9. Is formed. Further, on the side of the pixel electrode 9, a TFT element 30 which is a switching element for performing energization control to the pixel electrode 9 is formed. A data line 6 a is connected to the source of the TFT element 30. Image signals S1, S2,..., Sn are supplied to the data lines 6a from the data line driving elements described above.

  A scanning line 3 a is connected to the gate of the TFT element 30. Scanning signals G1, G2,..., Gm are supplied to the scanning line 3a in a pulsed manner from the scanning line driving element described above at a predetermined timing. On the other hand, the pixel electrode 9 is connected to the drain of the TFT element 30. When the TFT elements 30 serving as switching elements are turned on for a certain period by the scanning signals G1, G2,..., Gm supplied from the scanning line 3a, the image signals S1, S2,. Sn is written to the liquid crystal of each dot via the pixel electrode 9 at a predetermined timing.

  The predetermined level image signals S1, S2,..., Sn written in the liquid crystal are held for a certain period by a liquid crystal capacitor formed between the pixel electrode 9 and a common electrode described later. In order to prevent leakage of the held image signals S1, S2,..., Sn, a storage capacitor 17 is formed between the pixel electrode 9 and the capacitor line 3b, and is arranged in parallel with the liquid crystal capacitor. . Thus, when a voltage signal is applied to the liquid crystal, the alignment state of the liquid crystal molecules changes depending on the applied voltage level. Thereby, the light source light incident on the liquid crystal is modulated to produce image light.

  In the liquid crystal device of this embodiment, as shown in the plan view of FIG. 3, a rectangular array made of a transparent conductive material such as indium tin oxide (hereinafter referred to as ITO) is formed on the TFT array substrate. Shaped pixel electrodes 9 (the outlines of which are indicated by broken lines 9a) are arranged in a matrix. Further, data lines 6 a, scanning lines 3 a, and capacitor lines 3 b are provided along the vertical and horizontal boundaries of the pixel electrode 9. In the present embodiment, the rectangular area in which each pixel electrode 9 is formed is a dot, and the display can be performed for each dot arranged in a matrix.

  The TFT element 30 is formed around a semiconductor layer 1a made of a polysilicon film or the like. A data line 6 a is connected to a source region (described later) of the semiconductor layer 1 a through a contact hole 5. Further, a pixel electrode 9 is connected to a drain region (described later) of the semiconductor layer 1 a through a contact hole 8. On the other hand, a channel region 1a 'is formed in a portion of the semiconductor layer 1a facing the scanning line 3a.

  Further, as shown in the cross-sectional structure explanatory diagram of FIG. 4, this liquid crystal device is mainly composed of a TFT array substrate 10, a counter substrate 20 disposed opposite thereto, and a liquid crystal 50 sandwiched therebetween. Has been. The TFT array substrate 10 is mainly composed of a substrate body 10A made of a translucent material such as glass or quartz, a TFT element 30, a pixel electrode 9, an alignment film 16 and the like formed inside thereof. One counter substrate 20 is mainly composed of a substrate body 20A made of a light-transmitting material such as glass or quartz, and a common electrode 21 and an alignment film 22 formed inside thereof.

  A first light shielding film 11 a and a first interlayer insulating film 12 are formed on the surface of the TFT array substrate 10. A semiconductor layer 1a is formed on the surface of the first interlayer insulating film 12, and a TFT element 30 is formed around the semiconductor layer 1a. A channel region 1a 'is formed in a portion of the semiconductor layer 1a facing the scanning line 3a, and a source region and a drain region are formed on both sides thereof. Since the TFT element 30 employs an LDD (Lightly Doped Drain) structure, a high concentration region having a relatively high impurity concentration and a low concentration region (LDD region) having a relatively low impurity concentration in the source region and the drain region, respectively. And are formed. That is, a low concentration source region 1b and a high concentration source region 1d are formed in the source region, and a low concentration drain region 1c and a high concentration drain region 1e are formed in the drain region.

  A gate insulating film 2 is formed on the surface of the semiconductor layer 1a. A scanning line 3a is formed on the surface of the gate insulating film 2, and a portion facing the channel region 1a 'constitutes a gate electrode. A second interlayer insulating film 4 is formed on the surfaces of the gate insulating film 2 and the scanning line 3a. A data line 6a is formed on the surface of the second interlayer insulating film 4, and the data line 6a is connected to the high-concentration source region 1d through a contact hole 5 formed in the second interlayer insulating film 4. . Further, a third interlayer insulating film 7 is formed on the surfaces of the second interlayer insulating film 4 and the data line 6a. A pixel electrode 9 is formed on the surface of the third interlayer insulating film 7, and the pixel electrode 9 is a high-concentration drain through a contact hole 8 formed in the second interlayer insulating film 4 and the third interlayer insulating film 7. It is connected to the area 1e. Further, an inorganic alignment film 16 is formed so as to cover the pixel electrode 9, and the alignment of liquid crystal molecules when a non-selection voltage is applied is regulated.

In the present embodiment, the first storage capacitor electrode 1f is formed by extending the semiconductor layer 1a. Further, the gate insulating film 2 is extended to form a dielectric film, and the capacitor line 3b is disposed on the surface thereof to form a second storage capacitor electrode. Thus, the above-described storage capacitor 17 is configured.
A first light shielding film 11 a is formed on the surface of the substrate body 10 </ b> A corresponding to the formation region of the TFT element 30. The first light shielding film 11a prevents light incident on the liquid crystal device from entering the channel region 1a ′, the low concentration source region 1b, and the low concentration drain region 1c of the semiconductor layer 1a.

  On the other hand, a second light shielding film 23 is formed on the surface of the substrate body 20A in the counter substrate 20. The second light shielding film 23 prevents light incident on the liquid crystal device from entering the channel region 1a ′, the low concentration source region 1b, the low concentration drain region 1c, and the like of the semiconductor layer 1a. It is provided in a region overlapping with the layer 1a. A common electrode 21 made of a conductor such as ITO is formed on the surface of the counter substrate 20 over substantially the entire surface. Furthermore, an inorganic alignment film 22 is formed on the surface of the common electrode 21 so that the alignment of liquid crystal molecules when a non-selection voltage is applied is regulated.

  Here, both the inorganic alignment film 16 on the TFT array substrate 10 side and the inorganic alignment film 22 on the counter substrate 20 side are characteristic components of the present invention. That is, in the present invention, these inorganic alignment films 16 and 22 are surface-treated with a plurality of silane coupling materials having different molecular weights as described above.

These inorganic alignment films 16 and 22 are made of a silicon oxide such as SiO ₂ or SiO, or a metal oxide such as Al ₂ O ₃ , ZnO, MgO or ITO, and the like in a thickness of 0.02 to 0.3 μm (preferably , 0.02 to 0.08 μm). In addition, for the production of these inorganic alignment films 16 and 22, a sputtering method such as an ion beam sputtering method or a magnetron sputtering method, a vapor deposition method, a sol-gel method, a self-organization method, or the like can be employed. In the present embodiment, the inorganic alignment films 16 and 22 are both made of silicon oxide mainly composed of SiO ₂ and formed by a conventionally known oblique deposition method.

  FIG. 5A illustrates a vapor deposition apparatus 503 as an example of a film formation apparatus that performs film formation by oblique vapor deposition. The vapor deposition apparatus 503 includes a vapor deposition source 512 that generates a vapor flow of the inorganic alignment film material, the TFT array substrate 10 before forming the inorganic alignment film, or the counter 20 (hereinafter simply referred to as the substrate 10) before forming the inorganic alignment film. And a holding mechanism 514 for holding (denoted (20)). In this vapor deposition apparatus 503, the substrate 10 (20) has a reference line X 1 connecting the vapor deposition source 512 and the position of the center of gravity of the substrate surface of the substrate 10 (20), and a straight line X 2 perpendicular to the film formation surface of the substrate 10 (20). Is held by the holding mechanism 514 so that the angle θ0 formed by Therefore, an alignment film is formed on the substrate 10 (20) and the traveling direction of the inorganic material generated by the vapor deposition source 512, that is, the direction in which the inorganic material flies, as indicated by the arrow Y1 in FIGS. The angle θ1 formed with the substrate surface (deposition surface) to be adjusted can be adjusted by changing the angle θ0. The angle θ1 is set to a predetermined value for arranging columnar structures to be described later on the substrate surface so as to obtain a surface shape effect for performing alignment control in the alignment film 16 (22). . However, in this embodiment, since oblique deposition is performed, the angle θ1 is less than 90 °.

  When oblique vapor deposition is performed by such a vapor deposition apparatus, as shown by an arrow in FIG. 5B, the alignment film material sublimated from the vapor deposition source 512 has a substantially constant incident angle (inclination) with respect to the substrate 10 (20). Angle). Then, as shown in FIG. 6A, the alignment film material is deposited in an oblique column shape on the substrate 10 (20), thereby forming a columnar structure 16a (22a) of an inorganic material (silicon oxide). The columnar structures 16a (22a) are formed innumerably on the surface of the substrate 10 (20), whereby the inorganic alignment film 16 (22) is formed. Thus, when the columnar structure 16a (22a) is formed at a predetermined inclination angle, and thereby the inorganic alignment film 16 (22) is formed, in the liquid crystal device 60, the liquid crystal along the columnar structure 16a (22a) is formed. By aligning the molecules, a pretilt angle is imparted to the liquid crystal molecules. That is, as described above, the alignment of liquid crystal molecules is regulated in a predetermined direction by the inorganic alignment films 16 and 22 when a non-selection voltage is applied.

Further, in the columnar structure 16a (22a) formed in this way, when viewed at the atomic level, as shown in FIG. 7A, a large number of hydroxyl groups are present on the surface, and silanol groups (Si-OH) ) Is formed.
Therefore, in the present invention, the inorganic alignment film 16 (22) (columnar structure 16a () is formed by a silane coupling material in order to eliminate the activity of the hydroxyl group in the silanol group and to avoid the above-described disadvantage caused by the hydroxyl group. 22a)) is surface treated. That is, the inorganic alignment films 16 and 22 formed by such an oblique deposition method are surface-treated with a plurality of silane coupling materials having different molecular weights as described above. The number (type) of silane coupling materials to be used may be 3 or more, but it is sufficient to use two types of silane coupling materials having different molecular weights in consideration of the effect obtained by the treatment.

Here, the silane coupling material has an organic functional unit and a hydrolyzable group in one molecule, thereby linking the inorganic substance and the organic resin, and the physical strength, water resistance, light resistance, adhesion of the material. It is possible to improve the property. Specifically, a silicon atom (Si) has one organic functional group and a functional group that reacts with a few inorganic substances, and is represented by the following formula.
YSiX ₃ (formula)
X: hydrolysis group bonded to a silicon atom, -OR, -Cl, -NR _2, etc. Y: organic functional group reactive such as an organic matrix, an alkyl group (-R), such as

The silane coupling material to be used is not particularly limited as long as the organic functional group has good water repellency and good light resistance. Specifically, the organic functional group in the above formula is used. The group (Y) is preferably an alkyl group. Also, the hydrolyzable group is not particularly limited, but for example, when a group having a low molecular weight such as a methoxy group (—OCH ₃ ) reacts and is added to the surface of the inorganic alignment film as described later, it is difficult to cause steric hindrance. It is preferable for such reasons.

Moreover, about the multiple types (for example, 2 types) silane coupling material to be used, a thing with high mutual affinity is preferable, therefore it has the same group about the thing of the same system, ie, a hydrolysis group, About an organic functional group Only those having different molecular weights are preferred. In addition, when an alkyl group is used as the organic functional group (Y) as described above, the size of the molecular weight is determined by the number of carbon atoms, and the larger the carbon number, the longer the group, the larger the molecular weight. Here, when the carbon number of the alkyl group, that is, _{n in} (C _n H _{2n + 1} ) — is 18 or more, water repellency and light resistance can be favorably imparted to the inorganic alignment film after the surface treatment. Experiments have confirmed that there is an effect of sufficiently improving the water repellency and light resistance of the alignment film.

Therefore, in the present invention, as the silane coupling material having a larger molecular weight, one having an alkyl group having 18 or more carbon atoms as an organic functional group is preferably used. On the other hand, as a material having a small molecular weight with respect to this silane coupling material, for example, a material having an alkyl group having 8 or less carbon atoms as an organic functional group is used. In this embodiment, for this reason, as the silane coupling material having a larger molecular weight, the one represented by the following chemical formula A (having 18 carbon atoms in the alkyl group) is also used, and the molecular weight is small. As the silane coupling material, the one represented by the following chemical formula B (the alkyl group having 2 carbon atoms) is used.
A; (C ₁₈ H ₃₇ ) Si (OCH ₃ ) ₃
B; (C ₂ H ₅ ) Si (OCH ₃ ) ₃

In addition, when performing surface treatment with two kinds of silane coupling materials having different molecular weights, two methods, a gas phase method and a liquid phase method, are possible.
In the vapor phase method, for example, a substrate on which an inorganic alignment film is formed is placed in a CVD apparatus, and two types of silane coupling materials are introduced as vapors, respectively, and the inorganic alignment film is surface-treated with the vapors of the silane coupling materials. . At that time, when the boiling points of the two types of silane coupling materials are close to each other, they can be simultaneously placed in the apparatus, and the surface treatment can be simultaneously performed.

  However, in the present invention, it is preferable that the surface treatment is performed first with the silane coupling material A having a large molecular weight, and then the surface treatment is performed with the silane coupling material B having a small molecular weight. As described above, first, the surface of the inorganic alignment film 16 (22) can be mainly made water-repellent by first performing the surface treatment with the silane coupling material A having a large molecular weight. However, in that case, as shown in FIG. 6B, steric hindrance occurs due to the large molecular weight, and the silane coupling material A causes, for example, the gap in the surface layer portion of the inorganic alignment film 16 (22). It does not penetrate sufficiently and is therefore difficult to surface treat. Further, as shown in FIG. 7 (b), it becomes difficult to react even with an unreacted hydroxyl group between hydroxyl groups reacted with a hydrolyzable group (methoxy group) of this large silane coupling material A. However, after that, by performing surface treatment with the silane coupling material B having a small molecular weight, as shown in FIG. 6 (c), the surface treatment is satisfactorily permeated into the gap in the surface layer portion of the inorganic alignment film 16 (22). Further, the silane coupling material B can be reacted with an unreacted hydroxyl group as shown in FIG. In addition, A and B shown in FIG. 6B and FIG. 6C indicate silane coupling materials after reacting with silanol and releasing one methoxy group.

  In this way, almost the entire surface layer portion of the inorganic alignment film 16 (22) can be satisfactorily surface-treated, thereby improving moisture resistance and improving light resistance due to water repellency. Further, since the micro pores (holes) on the surface of the porous inorganic alignment film 16 (22) are filled with the silane coupling materials A and B, and the surface can be made dense, the inorganic alignment film 16 It is also possible to improve the adhesion between (22) and the sealing material 19 and to increase the airtightness at the seal portion at the interface between the inorganic alignment film 16 (22) and the sealing material 19.

  Moreover, also when surface-treating by a liquid phase method, two types of silane coupling materials are melt | dissolved in a suitable solvent, and the inorganic alignment film 16 (22) is simultaneously surface-treated with these, or it separately surface-treats. Can do. As a specific method for the surface treatment, a contact treatment by a coating method such as a spin coating method, a contact treatment by a spray method, or a dipping method can be employed. In particular, when the substrate 10 (20) is immersed in a solution of a silane coupling material to surface-treat the surface layer portion of the inorganic alignment film 16 (22), ultrasonic waves are applied to the substrate 10 (20) and the solution in that state. Alternatively, it is preferable to reduce the pressure in the processing chamber.

By performing the ultrasonic treatment and the pressure reduction treatment in this way, the silane coupling material solution enters better into the gap in the surface layer portion of the inorganic alignment film 16 (22), and the silanol group (Si—OH) in this gap. ).
Also in this liquid phase method, for the same reason as in the gas phase method, the surface treatment is first performed with the silane coupling material A having a high molecular weight, and then the surface treatment is performed with the silane coupling material B having a low molecular weight. Is preferably performed.

  However, in both the gas phase method and the liquid phase method, the surface treatment may be performed simultaneously with the silane coupling material A having a high molecular weight and the silane coupling material B having a low molecular weight, and further, silane having a low molecular weight. The surface treatment may be performed first with the coupling material B, and then the surface treatment may be performed with the silane coupling material A having a large molecular weight. Even in this case, since the silanol group on the surface of the inorganic alignment film 16 (22) exhibits a certain degree of selectivity, the two types of silane coupling materials A and B react with the silanol group, respectively, and the inorganic alignment film 16 ( 22).

As described above, the inorganic alignment film 16 (22) subjected to the surface treatment in this way has improved moisture resistance and improved light resistance due to water repellency as described above. Further, the adhesiveness between the sealing material 19 and the sealing material 19 is enhanced, and therefore the airtightness at the sealing portion at the interface between the inorganic alignment film 16 (22) and the sealing material 19 is enhanced.
Here, in particular, with respect to moisture resistance (moisture resistance), in addition to the surface layer portion being water-repellent by the silane coupling material A having a high molecular weight, the inorganic alignment film 16 ( 22) Since the water-repellent property is formed even in the gap between the surface layer portions, the moisture resistance (moisture resistance) of the entire film is improved by the following mechanism.

  That is, in the inorganic alignment film 16 (22) in the state shown in FIG. 6A before the water repellent treatment is performed, the presence of the hydrophilic silanol group causes the two in FIG. Water (humidity) is likely to exist in the region W indicated by the dotted line. Therefore, when the substrates 10 and 20 are assembled without performing the water repellency treatment (surface treatment) on the inorganic alignment films 16 and 22 and the liquid crystal device is formed, when water or moisture enters from the outside, By entering the surface layer portion of the inorganic alignment films 16 and 22 and directly contacting the liquid crystal, the liquid crystal is deteriorated and its characteristics are deteriorated.

  Also, the surface layer portions of the inorganic alignment films 16 and 22 are formed by performing water repellency treatment (surface treatment) with the silane coupling A having a large molecular weight and mainly repelling the surface layer portion of the inorganic alignment film 16 (22). In FIG. 6B, the region where water (humidity) tends to exist can be narrowed to a region where the silane coupling A does not react, as indicated by a two-dot chain line in FIG. However, even in this case, since the silane coupling A does not react particularly in the gap between the inorganic alignment films 16 (22), the region W where water (humidity) still exists remains relatively wide. Yes. Therefore, when the substrates 10 and 20 are assembled in this state and the liquid crystal device is formed, when water or moisture enters from the outside, it also enters the surface layers of the inorganic alignment films 16 and 22 and directly contacts the liquid crystal. There is a risk of deteriorating the properties of the liquid crystal.

Therefore, the water repellent treatment (surface treatment) is performed again with the silane coupling material B having a small molecular weight, and the inorganic alignment film 16 (22) is mainly made water repellent in the gap portion of the surface portion of the inorganic alignment film 16, The region W where moisture (humidity) is likely to exist in the surface layer portion 22 can be further narrowed to a region where the silane coupling material B is not disposed, as shown by a two-dot chain line in FIG. .
Thus, after performing water-repellent treatment (surface treatment) a plurality of times with silane coupling materials having different molecular weights, the substrates 10 and 20 are assembled into the liquid crystal device of the present invention. Even if water or moisture tries to enter from the outside, it is difficult for the water or moisture to enter the surface layer of the inorganic alignment films 16 and 22 that have been made water-repellent. It will not penetrate.

  As shown in FIG. 4, the liquid crystal device 60 of the present embodiment includes a TFT array substrate 10 having an inorganic alignment film 16 (22) subjected to surface treatment (water repellency treatment) as described above, a counter substrate 20, and the like. In between, a liquid crystal 50 made of nematic liquid crystal or the like is sandwiched and sealed with a sealing material 19 (see FIG. 1). Nematic liquid crystal molecules have a positive dielectric anisotropy, and are horizontally aligned along the substrate when a non-selection voltage is applied, and vertically aligned along the electric field direction when a selection voltage is applied. The nematic liquid crystal molecules have positive refractive index anisotropy, and the product (retardation) Δnd of the birefringence and the liquid crystal thickness is, for example, about 0.40 μm (60 ° C.). Note that the alignment regulation direction by the inorganic alignment film 16 of the TFT array substrate 10 and the alignment regulation direction by the inorganic alignment film 22 of the counter substrate 20 are set to be twisted by about 90 °. Thereby, the liquid crystal device 60 of the present embodiment operates in the twisted nematic mode.

  In addition, polarizing plates 18 and 28 made of a material obtained by doping polyvinyl alcohol (PVA) with iodine or the like are disposed outside the substrates 10 and 20. The polarizing plates 18 and 28 are preferably mounted on a support substrate made of a high thermal conductivity material such as sapphire glass or quartz, and are separated from the liquid crystal device 60. Each of the polarizing plates 18 and 28 has a function of absorbing linearly polarized light in the absorption axis direction and transmitting linearly polarized light in the transmission axis direction. The polarizing plate 18 on the TFT array substrate 10 side is arranged so that its transmission axis substantially coincides with the alignment regulating direction of the alignment film 16. The polarizing plate 28 on the counter substrate 20 side has its transmission axis aligned with the alignment film 22. It arrange | positions so that it may correspond with a regulation direction substantially.

The liquid crystal device 60 is disposed with the counter substrate 20 facing the light source. Of the light source light, only linearly polarized light that matches the transmission axis of the polarizing plate 28 passes through the polarizing plate 28 and enters the liquid crystal device 60.
In the liquid crystal device 60 when the non-selection voltage is applied, the liquid crystal molecules horizontally aligned with respect to the substrate are arranged in a spiral manner by twisting about 90 ° in the thickness direction of the liquid crystal 50. Therefore, the linearly polarized light incident on the liquid crystal device 60 is rotated about 90 ° and emitted from the liquid crystal device 60. Since this linearly polarized light coincides with the transmission axis of the polarizing plate 18, it passes through the polarizing plate 18. Accordingly, white display is performed in the liquid crystal device 60 when the non-selection voltage is applied (normally white mode).

  Further, in the liquid crystal device 60 when the selection voltage is applied, the liquid crystal molecules are vertically aligned with respect to the substrate. Therefore, the linearly polarized light incident on the liquid crystal device 60 is emitted from the liquid crystal device 60 without being rotated. Since this linearly polarized light is orthogonal to the transmission axis of the polarizing plate 18, it does not pass through the polarizing plate 18. Accordingly, black display is performed in the liquid crystal device 60 when the selection voltage is applied.

In the liquid crystal device 60 having such a configuration, since the inorganic alignment films 16 and 22 are surface-treated with silane coupling materials having different molecular weights, the moisture proofness is improved by water repellency as described above. Therefore, the deterioration of the liquid crystal due to moisture (humidity) is surely prevented, and the quality is stabilized over a long period of time, that is, the life is extended. In addition, since the light resistance is also improved, this also extends the life.
Further, since the airtightness at the seal portion at the interface between the inorganic alignment films 16 and 22 and the sealing material 19 is enhanced, the moisture-proof property at the seal portion is increased, and thus the life is also extended in this respect. It will be a thing.
In addition, since the inorganic alignment films 16 and 22 are used as the alignment films, they are superior in light resistance and heat resistance as compared with the organic alignment films, and therefore are excellent in durability.

Further, even in such a manufacturing method of the liquid crystal device 60, the inorganic alignment films 16 and 22 are surface-treated with silane coupling materials having different molecular weights, so that the lifetime of the liquid crystal device 60 obtained as described above is extended. Can be achieved.
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

(projector)
Next, a projector as an embodiment of the electronic apparatus of the invention will be described with reference to FIG. FIG. 8 is a schematic configuration diagram showing a main part of the projector. This projector includes the liquid crystal device according to the above-described embodiment as light modulation means.

  8, 810 is a light source, 813 and 814 are dichroic mirrors, 815, 816 and 817 are reflection mirrors, 818 is an incident lens, 819 is a relay lens, 820 is an exit lens, and 822, 823 and 824 are liquid crystal devices of the present invention. 825 is a cross dichroic prism, and 826 is a projection lens. The light source 810 includes a lamp 811 such as a metal halide and a reflector 812 that reflects the light of the lamp.

  The dichroic mirror 813 transmits red light contained in white light from the light source 810 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 817 and is incident on the light modulation means 822 for red light. The green light reflected by the dichroic mirror 813 is reflected by the dichroic mirror 814 and is incident on the light modulating means 823 for green light. Further, the blue light reflected by the dichroic mirror 813 passes through the dichroic mirror 814. For blue light, in order to prevent light loss due to a long optical path, a light guide means 821 including a relay lens system including an incident lens 818, a relay lens 819, and an exit lens 820 is provided. Blue light is incident on the light modulating means 824 for blue light through the light guiding means 821.

  The three color lights modulated by the respective light modulation means 822, 823, and 824 are incident on the cross dichroic prism 825. The cross dichroic prism 825 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  The projector having such a configuration includes the liquid crystal device as a light modulation unit. Since the liquid crystal device includes the inorganic alignment film having excellent light resistance and heat resistance as described above, the alignment film is not deteriorated by strong light or heat irradiated from the light source. In addition, since this projector is equipped with a liquid crystal device that reliably prevents deterioration of the liquid crystal due to moisture (humidity) and has a long life, the electronic device itself is also reliable with a long life. It becomes a high quality thing.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the gist of the present invention. For example, in the above embodiment, a liquid crystal device including a TFT as a switching element has been described as an example. However, the present invention is applied to a liquid crystal device including a two-terminal element such as a thin film diode as a switching element. It is also possible. In the above embodiment, the transmissive liquid crystal device has been described as an example. However, the present invention can also be applied to a reflective liquid crystal device. In the above embodiment, the liquid crystal device functioning in the TN (Twisted Nematic) mode has been described as an example. However, the present invention can be applied to a liquid crystal device functioning in the VA (Vertical Alignment) mode. Further, in the embodiment, the description has been given by taking a three-plate projection display device (projector) as an example, but the present invention can also be applied to a single-plate projection display device or a direct-view display device.

  The liquid crystal device of the present invention can also be applied to electronic devices other than projectors. A specific example is a mobile phone. This mobile phone includes the liquid crystal device according to each of the above-described embodiments or modifications thereof in a display unit. Other electronic devices include, for example, IC cards, video cameras, personal computers, head-mounted displays, fax machines with display functions, digital camera finders, portable TVs, DSP devices, PDAs, electronic notebooks, and electronic bulletin boards. And advertising announcement displays.

It is a top view of the TFT array substrate of a liquid crystal device. It is an equivalent circuit diagram of a liquid crystal device. It is explanatory drawing of the planar structure of a liquid crystal device. It is explanatory drawing of the cross-section of a liquid crystal device. (A) is a schematic diagram of a vapor deposition apparatus, (b) is explanatory drawing of oblique vapor deposition. (A)-(c) is explanatory drawing of the surface treatment to an inorganic oriented film. (A)-(c) is reaction explanatory drawing of an inorganic alignment film and a silane coupling material. It is a schematic block diagram which shows the principal part of a projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Substrate (TFT array substrate), 16 ... Inorganic alignment film, 20 ... Substrate (opposite substrate), 22 ... Inorganic alignment film, 50 ... Liquid crystal, 60 ... Liquid crystal device, A ... Large molecular weight silane coupling, B ... Small Molecular weight silane coupling

Claims (8)

A liquid crystal device having a liquid crystal sandwiched between a pair of substrates facing each other,
An inorganic alignment film is provided on each inner surface of the pair of substrates;
The liquid crystal device, wherein the inorganic alignment film is surface-treated with a plurality of silane coupling materials having different molecular weights.   The liquid crystal device according to claim 1, wherein the inorganic alignment film is made of silicon oxide.   The plurality of silane coupling materials have an alkyl group as an organic functional group, and the alkyl group of the silane coupling material having a higher molecular weight has more carbon atoms than the alkyl group of the silane coupling material having a lower molecular weight. The liquid crystal device according to claim 1, wherein:   4. The liquid crystal device according to claim 3, wherein the silane coupling material having a higher molecular weight among the plurality of silane coupling materials has an alkyl group having 18 or more carbon atoms. A method of manufacturing a liquid crystal device in which a liquid crystal is sandwiched between a pair of substrates facing each other,
Forming an inorganic alignment film on each inner surface of the pair of substrates;
And a step of surface-treating the inorganic alignment film with a plurality of silane coupling materials having different molecular weights.   6. The method of manufacturing a liquid crystal device according to claim 5, wherein the inorganic alignment film is formed by an oblique deposition method. As the plurality of silane coupling materials, one having an organic functional group that is an alkyl group is prepared, and the alkyl group of the silane coupling material having a higher molecular weight is the alkyl group of the silane coupling material having a lower molecular weight. Preparing the plurality of silane coupling materials so that the number of carbon atoms is increased,
7. The liquid crystal according to claim 5, wherein in the surface treatment step, the surface treatment is first performed with a silane coupling material having a high molecular weight, and then the surface treatment is performed with a silane coupling material having a low molecular weight. apparatus. An electronic device comprising the liquid crystal device according to any one of claims 1 to 4, or the liquid crystal device obtained by the manufacturing method according to any one of claims 5 to 7. machine.

Images