JP2010020253A - Liquid crystal apparatus and method of producing the same - Google Patents

Abstract

Disclosed is a liquid crystal device that easily expresses a splay-bend alignment transition and that can easily maintain the bend alignment after the transition, and has a superior display quality, and a method for manufacturing the same.
A liquid crystal comprising a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy, and a pair of substrates through which at least one substrate transmits light and sandwiching the liquid crystal layer. A liquid crystal device that performs retardation control of a liquid crystal layer by a voltage applied to the layer, wherein a display region portion in which a plurality of pixel electrodes are arranged on one of the substrates, and non-display other than the display region portion A region portion is disposed, a counter electrode made of a transparent electrode is disposed on the other substrate, an inorganic alignment film is disposed on the liquid crystal layer side of the pair of substrates, and is disposed on at least one substrate The said inorganic alignment film is a liquid crystal device from which the film density of the inorganic alignment film in a display area part and a non-display area part differs.
[Selection] Figure 6

Description

  The present invention relates to a liquid crystal device and a manufacturing method thereof, and more particularly to a liquid crystal device using an OCB (Optically Compensated Bend) mode capable of realizing a high-speed response and a manufacturing method thereof.

Various liquid crystal alignment modes are used for the liquid crystal element depending on the application. For example, TN (Twisted Nematic) mode, VA (Vertical Aligned) mode, IPS (In Plane Switching) mode, OCB (Optically)
The Compensated Bend) mode is well known. These liquid crystal alignment modes can be determined by the physical properties of the liquid crystal composition and the characteristics of the alignment film.

  In recent years, development of a liquid crystal device having high-speed response for excellent moving image display has become active, and among the liquid crystal alignment modes, the OCB mode has a relatively high-speed response and attracts attention. Yes.

  In the OCB mode, a liquid crystal alignment state called bend alignment shown in FIG. 4 is used for display operation. However, alignment transition from the splay alignment in the initial alignment state as shown in FIG. 3 is required for forming the bend alignment. For this splay-bend alignment transition, a transition voltage higher than a certain voltage is required. Since the driving voltage of the liquid crystal element increases when the transition voltage increases, it is preferably as low as possible.

To lower the transition voltage, it is effective to set a high pretilt angle, which is the tilt angle of the liquid crystal alignment film and the liquid crystal molecules immediately above it, and to reduce the elastic constant (K ₃₃ / K ₁₁ ) of the liquid crystal composition. It has been known. In particular, by setting the pretilt angle to 40 ° or more, a transition voltage is not required, and it is possible to form a bend alignment without going through a splay alignment state.

However, if the pretilt angle is set high, bend transition is likely to occur, but the retardation of the liquid crystal layer is lowered, and as a result, there is a problem that light utilization efficiency is lowered.
In order to solve this problem, there is a report for facilitating the bend alignment transition even at a low pretilt angle.

  For example, Patent Document 1 forms a region that expresses a plurality of pretilt angles in a substrate surface. Specifically, by enclosing a low pretilt angle region with a high pretilt angle region, the occurrence of a spray-bend transition is facilitated. Aiming to be. As a method for forming a low pretilt angle region in Patent Document 1, the following method is cited. After forming the high pretilt angle region on the substrate by the oblique vapor deposition method with a vapor deposition angle of 80 °, the vapor deposition region is limited to only the pixel region by using a mask, and the vapor deposition direction is set to 90 ° by rotating the substrate by 90 °. By rotating, an oblique deposition film is produced at a deposition angle of 60 °. By such a manufacturing method, the pixel region has a low pretilt angle by 60 ° vapor deposition, and the interpixel region has a high pretilt angle by 80 ° vapor deposition. In addition, when the deposition angle is 60 ° and the deposition angle is 80 °, it is known that the liquid crystal alignment in the azimuth direction, that is, the in-plane direction of the substrate is rotated by 90 °. Since the vapor deposition direction at a vapor deposition angle of 80 ° is rotated by 90 °, the liquid crystal alignment directions in the azimuth angle direction coincide with each other.

Further, in Patent Document 2, a polyimide alignment film whose pretilt angle is changed by ultraviolet irradiation is used, and the pretilt angle of the pixel region portion is set to be higher than the pretilt angle of the interpixel region by irradiating the pixel region portion with ultraviolet rays. Is set too low.
JP 2007-017502 A JP 2000-330141 A

  However, the method of Patent Document 1 is not a structure sufficient for reducing the bend transition voltage of the liquid crystal layer, and further reduction of the bend transition voltage and stabilization of the bend alignment are desired. Moreover, since it is necessary to perform deposition by rotating the substrate 90 ° twice at different deposition angles (for example, 60 ° and 80 °) during the preparation of the alignment film, there is a problem that the process becomes complicated.

Moreover, since the method of Patent Document 2 uses an organic alignment film, there is a problem that it is difficult to apply in an environment where high-intensity light is used.
The present invention has been made in view of the above-described problems, and can easily exhibit a splay-bend alignment transition without maintaining a structure such as a notch between pixel electrodes or pixels, and can maintain a bend alignment after the transition. It is an object of the present invention to provide a liquid crystal device that is easy and has excellent display quality and a method for manufacturing the same.

  As a result of intensive investigations, the present inventors have found out conditions for producing an inorganic alignment film for expressing a pretilt angle of 40 ° or more when an inorganic alignment film is used, and in the process, a high pretilt angle is expressed. It has been found that by irradiating such an obliquely deposited film with an ion beam from a certain direction, only the pretilt angle in the ion beam irradiation region can be selectively reduced.

  In addition, by performing a splay-bend transition of the liquid crystal in the splay alignment region surrounded by the bend alignment region, the reverse transition of the liquid crystal in the region surrounded by the bend alignment region (transition from the bend alignment to the splay alignment) It was found that it was very slow compared to the normal reverse transition or no reverse transition occurred.

Based on these facts, the following invention was completed.
That is, the first invention according to the present invention is a pair of substrates in which at least one substrate that transmits light is sandwiched and opposed to a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy. A display region portion in which a plurality of pixel electrodes are disposed and a non-display region portion other than the display region portion are disposed on one of the substrates, A counter electrode is disposed on one substrate, an inorganic alignment film is disposed on the liquid crystal layer side of the pair of substrates, and the inorganic alignment film disposed on at least one of the substrates is not displayed on the display region portion The film density in the region is different.

  According to a second aspect of the present invention, there is provided a pair of substrates in which at least one substrate that transmits light is sandwiched between a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy and sandwiching the liquid crystal layer. A method of manufacturing a liquid crystal device comprising: a step of forming an inorganic alignment film by obliquely depositing an inorganic material on a substrate; and a certain irradiation angle in a partial region of the inorganic alignment film And a step of forming a display region portion and a non-display region portion having different film densities of the inorganic alignment film by irradiating with an ion beam.

  According to the present invention, a liquid crystal device capable of achieving a partial decrease in pretilt angle by irradiating an inorganic alignment film in the display region with an ion beam and reducing the film density of the display region is provided. Can be provided. In particular, by setting the non-display area portion to a pretilt angle that results in bend alignment when no voltage is applied, the splay-bend transition of the display area portion is facilitated and the stability of the bend alignment after the transition is improved. A liquid crystal device that can be manufactured and a method for manufacturing the same can be provided.

Hereinafter, the present invention will be described in detail.
A liquid crystal device according to the present invention includes a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy, and a pair of substrates that are opposed to each other with at least one substrate transmitting light. A liquid crystal device that performs retardation control of a liquid crystal layer by a voltage applied to the liquid crystal layer, wherein a display region portion in which a plurality of pixel electrodes are arranged on one of the substrates, and the display region portion A non-display area portion other than that is disposed, a counter electrode made of a transparent electrode is disposed on the other substrate, an inorganic alignment film is disposed on the liquid crystal layer side of the pair of substrates, and at least on one substrate The inorganic alignment film disposed in the substrate is characterized in that the inorganic alignment films in the display region portion and the non-display region portion have different film densities.

It is preferable that the film density of the inorganic alignment film in the display area is larger than the film density of the inorganic alignment film in the non-display area.
Preferably, the inorganic alignment film is formed of a columnar structure made of an inorganic material, and the arrangement direction of the columnar structure with respect to the substrate in the azimuth direction is the same in the display region portion and the non-display region portion.

The material constituting the inorganic alignment film is preferably silicon oxide.
The alignment state during the display operation of the liquid crystal layer is preferably bend alignment.
In the liquid crystal layer in the non-display area portion, it is preferable that the alignment state of the liquid crystal layer when no voltage is applied is bend alignment.

It is preferable that an electrode that does not contribute to display is disposed in the non-display area portion.
It is preferable that the shape of the display area part is a rectangle, and electrodes that do not contribute to display arranged in the non-display area part are formed along each side of the display area part.

  A method of manufacturing a liquid crystal device according to the present invention includes a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy, and a pair of substrates that are opposed to each other with at least one substrate transmitting light. A method of manufacturing a liquid crystal device that includes a liquid crystal layer and controls retardation of the liquid crystal layer by a voltage applied to the liquid crystal layer, and forming an inorganic alignment film made of an obliquely deposited film on the substrate by an obliquely deposited method Then, a partial region of the inorganic alignment film made of the obliquely deposited film is irradiated with an ion beam at a fixed irradiation angle to form a display region portion and a non-display region portion having different film densities of the inorganic alignment film. And a process.

  In the step of forming the oblique vapor deposition film by the oblique vapor deposition method, the vapor deposition angle is preferably 60 ° or more and less than 90 °.

In the step of irradiating a partial region of the inorganic alignment film with the ion beam, the irradiation direction of the ion beam in the step of irradiating the ion beam is parallel to a plane including the substrate normal and the vapor deposition direction in the oblique vapor deposition method. An inclination angle Θc of the columnar structure formed by the growth direction of the columnar structure and the substrate normal is 20 ° or more, and an ion beam irradiation angle formed by the growth direction of the columnar structure and the irradiation direction of the ion beam When the the theta _IB, based on the growth direction of the columnar _{structure, + 50 ° ≦ Θ IB ≦} + 100 ° ( where, theta _IB is 0 ° irradiation direction of the growth direction and the ion beam of the columnar structure is the same angle Θ _IB is − when the irradiation direction of the ion beam is inclined in the direction of the inclination angle Θc of the columnar structure, and the angle formed by the ion beam irradiation direction and the substrate normal is larger than Θc, and Θ _IB Is + Angle other than the range, i.e. theta _IB> is preferably in the range of ₀ °).

The ion beam is preferably an ion beam made of argon ions.
The method of irradiating an ion beam to a partial region of the oblique deposition film is preferably an ion beam irradiation method using a mask having an opening.

It is preferable that the size of the opening of the mask is a size including at least the display region.
Next, an embodiment of the liquid crystal device of the present invention will be described.

<About liquid crystal devices>
FIG. 1 is a conceptual diagram showing an example of the configuration of the liquid crystal device of the present invention. Reference numeral 101 denotes a pixel electrode, 102 denotes a transfer electrode, 103 denotes a seal portion, 104 denotes a sealing portion, 105 denotes an extraction electrode, 106 denotes a display region portion, 107 denotes a non-display region portion, and 108 denotes a display region portion and a non-display region portion It is a boundary. In FIG. 1A, the display area 107 indicates an inner area surrounded by a dotted line. The non-display area portion 107 indicates an area surrounded by the outer periphery of the display area portion 107 and the seal portion 103. FIG. 1B is an enlarged view of the boundary between the display area 107 and the non-display area 108 in FIG.

  The pixel electrode 101 is a transparent electrode such as ITO (Indium-Tin-Oxide) in the case of a transmission type, and a metal material that reflects incident light in the case of a reflection type, such as aluminum (Al) or silver (Ag). Etc. FIG. 1A and FIG. 1B show an electrode structure in the case of a reflection type. The counter electrode 302 shown in FIGS. 3 and 4 exists on the opposite side of the liquid crystal layer of these pixel electrodes, and the liquid crystal molecules are driven by a potential difference applied between the pixel electrode 101 and the counter electrode 302.

FIG. 3 is a conceptual diagram showing a splay alignment state used in the liquid crystal device of the present invention. FIG. 4 is a conceptual diagram showing a bend alignment state used in the liquid crystal device of the present invention.
In the present invention, it is preferable to install the transition electrode 102. The transfer electrode 102 does not contribute to display and is used to change the alignment state of the liquid crystal. In particular, it is used for the purpose of assisting the change in liquid crystal alignment state on the pixel electrode. For example, the liquid crystal alignment state is changed from the splay alignment shown in FIG. 3 to the bend alignment shown in FIG. 4, and the splay-bend alignment transition in the subsequent pixel region is promptly generated. The transfer electrode 102 only needs to be arranged outside the pixel electrode. However, in order to promptly change the orientation on the pixel electrode, the transfer electrode 102 is arranged outside along the four sides of the rectangular pixel electrode array. It is preferable.

However, if the change in the liquid crystal alignment on the pixel electrode, for example, the splay-bend alignment transition occurs quickly without using the transition electrode, the transition electrode 102 is not particularly required.
The present invention is characterized in that the film density of the inorganic alignment film is different between the display area 106 and the non-display area 107 shown in FIG. 1A existing in the area between the display area portion 106 and the seal portion 103. To do.

  Here, the film density of the inorganic alignment film in the present invention will be described. FIG. 2 is a conceptual diagram of a cross-sectional structure of an inorganic alignment film used in the liquid crystal device of the present invention. In FIG. 2, 201 is a substrate, 202 is a columnar structure, 203 is an inclination angle of the columnar structure, 204 is a film thickness, 205 is a vapor deposition direction, and 206 is a gap. The film density of the inorganic alignment film in the present invention represents the ratio of the columnar structures 202 made of an inorganic material constituting the inorganic alignment film and the gaps 206 existing between the plurality of columnar structures. The film density is expressed by how much the refractive index is lowered based on the refractive index of the columnar structure material in the absence of voids (that is, the film density is 100%). The refractive index can be measured by a measuring method such as spectroscopic ellipsometry.

  For example, when the film density ρ is determined by spectroscopic ellipsometry, the film density ρ can be measured by an effective medium approximation (EMA) method. If the medium satisfying the refractive index of the structure material forming the columnar structure and the gap between the columnar structures (here, n = 1 because it is air), after measuring the inorganic alignment film by spectroscopic ellipsometry, Calculation is possible by analyzing the measurement results using the EMA method.

  In the present invention, it is preferable that the film density of the inorganic alignment film in the display region is larger than the film density of the inorganic alignment film in the non-display region. The film density value of the inorganic alignment film in the display region portion is preferably 0.5 or more and 1.0 or less, and the film density value of the inorganic alignment film in the non-display region portion is preferably 0.1 or more and 0.7 or less. Further, (film density of inorganic alignment film in display region) − (inorganic alignment film in non-display region) = 0.1 or more is preferable.

  In particular, in the present invention, by irradiating the obliquely deposited film on the display region with an ion beam, the film density of the inorganic alignment film in the display region is set to be higher than that in the non-display region in the surrounding area. Can be high. As a result, different liquid crystal alignment states are generated in the display region portion and the non-display region portion. For this reason, the boundary 108 between the display region portion and the non-display region portion needs to be set at the outer peripheral portion of a rectangular pixel electrode array composed of a plurality of pixel electrodes.

  The boundary 108 between the display region portion and the non-display region portion is preferably set to the outside of the outer periphery of the pixel electrode array by the cell thickness of the liquid crystal cell. This is because the liquid crystal alignment in the non-display area can sufficiently affect the liquid crystal alignment in the display area by setting in this way. However, if the liquid crystal alignment state of the non-display area part can sufficiently affect the alignment state of the display area part by taking other means without setting as described above, the display area part and non-display The boundary 108 of the region portion is not limited to the above range.

When the transfer electrode 102 is provided, the boundary 108 between the display region portion and the non-display region portion is between the pixel electrode 101 and the transfer electrode 102 as shown in FIG. 1B and FIG.
Regardless of whether or not the ion beam is irradiated, the inorganic alignment films in the display region portion and the non-display region portion have the cross-sectional structure shown in FIG. That is, structural changes can occur due to ion beam irradiation, but the in-plane direction (azimuth angle direction) of the columnar structure 202 after ion beam irradiation needs to be substantially the same as the vapor deposition direction 205. . By maintaining the above structure, the in-plane liquid crystal alignment directions of the ion beam irradiation region and the non-irradiation region can be made substantially the same.

As the inorganic material used for the inorganic alignment film in the present invention, any material may be used as long as the liquid crystal is aligned in a certain azimuthal direction, for example, an oxide such as silicon dioxide (SiOx), monoxide. Silicon oxide such as silicon (SiO) (SiOx: about x = 1 to 2), magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), zirconium oxide ( ZrO ₂ ), chromium oxide (Cr ₂ O ₃ ), cobalt oxide (Co ₃ O ₄ ), iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ), and fluorides such as magnesium fluoride (MgF ₂ ), Alternatively, nitrides such as silicon nitride (SiNx), aluminum nitride (AlN), and the like can be given.

However, it is preferable to use silicon oxide (SiOx) such as silicon dioxide (SiO ₂ ) and silicon monoxide (SiO) in order to sufficiently exhibit the effects of the present invention. The liquid crystal alignment state of these materials can be controlled relatively freely depending on the formation conditions.

  FIG. 3 is a schematic cross-sectional view of a part of the display region portion 105 of the liquid crystal device shown in FIG. Here, 301 is an upper substrate, 302 is a counter electrode, 303 is an inorganic alignment film A, 304 is an inorganic alignment film A ′, 305 is a pixel electrode, 306 is a lower substrate, and 307 is a liquid crystal layer A.

Similarly, FIG. 4 shows a schematic sectional view of a part of the non-display area 107 in FIG. Here, 401 is an inorganic alignment film B, 402 is an inorganic alignment film B ′, and 403 is a liquid crystal layer B.
At least one of the inorganic alignment film A303 and the inorganic alignment film A′304 needs to have the above-described film density higher than the inorganic alignment films B401 and B′402 in the non-display region. With this configuration, the pretilt angle of the display area can be set lower than that of the non-display area.

  Here, the pretilt angle will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view of a liquid crystal cell used for measuring a pretilt angle. 501 is a pretilt angle θp, 502 is a liquid crystal molecule, 503 is an alignment film, 504 is a glass substrate, and 505 is an alignment treatment direction. The pretilt angle 501 of the alignment film 503 is measured by a method such as a crystal rotation method or a magnetic field threshold method. At that time, as the alignment film 503, the same alignment film is used for both the upper and lower substrates, and a liquid crystal cell is manufactured facing each other so that the alignment treatment direction 505 is an antiparallel (antiparallel) direction. By manufacturing such a liquid crystal cell, the liquid crystal molecules 502 are aligned in the direction as shown in FIG. 5, and the pretilt angle 501 of the alignment film 503 can be measured. The pretilt angle in the present invention is measured using the liquid crystal cell shown in FIG.

  As a method for increasing the film density of the inorganic alignment films A303 and A'304 in the display region portion, a method of irradiating an ion beam described in a method for manufacturing a liquid crystal device described later is preferably used. By using this method, the film density of the target portion can be controlled with high accuracy, and as a result, the pretilt angle of the irradiation unit can be controlled with high accuracy. However, in the present invention, other methods can be used without being limited to ion beams as long as the same effect can be obtained by irradiation with other methods, for example, other energy beams.

  When the pretilt angle of the display region is 40 ° or less, the splay alignment state as shown in the liquid crystal layer A307 in FIG. If the pretilt angle of the display area is low, the amount of retardation of the liquid crystal layer increases, which is advantageous for display. However, in the initial state, the bend alignment state shown in the liquid crystal layer B403 of FIG.

  In the present invention, the transition from the splay alignment of the display region to the bend alignment is facilitated by setting the pretilt angle of the non-display region that does not contribute to display to be high and forming a bend alignment state when no voltage is applied. In addition, the reverse transition from the bend alignment to the splay alignment in the display region is suppressed.

  For this purpose, the inorganic alignment films B401 and B′402 in the non-display area portion are preferably alignment films having a film density that expresses a high pretilt angle, specifically, a pretilt angle of 40 ° or more. It is preferable to use an inorganic alignment film having a film density. By using such an inorganic alignment film, the alignment state of the non-display region portion easily becomes the bend alignment state shown in the liquid crystal layer B403 in FIG. Because the non-display area is in the bend alignment state, the orientation of the display area surrounded by the non-display area is easily transferred to the bend alignment, and the reverse transition from the bend alignment to the splay alignment is less likely to occur. is there.

  Next, a boundary portion between the display area portion and the non-display area portion will be described with reference to the drawings. FIG. 6 is a schematic cross-sectional view of the boundary portion between the display area portion and the non-display area portion shown in FIG. Here, 601 is a transition electrode, 602 is a liquid crystal layer A, and 603 is a liquid crystal layer B.

  As shown in FIG. 6, the boundary 108 between the display area portion and the non-display area portion is set outside the pixel electrode 305. When the transfer electrode is installed as shown in FIG. 6, it is installed between the transfer electrode 601 and the outer peripheral end of the pixel electrode 305 as described above. Therefore, at least one of the inorganic alignment films A303 and A′304 having a film density higher than that of the inorganic alignment film in the non-display region is formed on the inner side (the side on which the pixel electrode is installed in FIG. 6). The

Next, a method for manufacturing the liquid crystal device of the present invention will be described.
The manufacturing method of the liquid crystal device of the present invention includes the following steps.
(A) Process: Substrate preparation process (b) Process: Process for forming obliquely deposited film (c) Process: Process for partially irradiating ion beam (d) Process: Application of sealing agent, substrate bonding process (e Step: Liquid crystal injection / liquid crystal cell sealing step (f) Step: Liquid crystal alignment treatment step (g) Step: Wiring connection step

  FIG. 7 is a process diagram illustrating each process in the method for manufacturing a liquid crystal device of the present invention. In FIG. 7, 1601 is an electrode / circuit formation substrate, 1602 is a counter electrode substrate, 1603 is an oblique deposition film, 1604 is an inorganic alignment film irradiated with an ion beam, 1605 is a mask, 1606 is a non-display area portion, and 1607 is a display area. 1608 is a sealing portion, 1609 is a liquid crystal layer 1, 1610 is a liquid crystal layer 2, and 1611 is a flexible cable.

  Among these, the process that is a feature of the present invention is the process (b) and the process (c), and the other processes are processes common to the manufacturing methods of other liquid crystal devices. Therefore, in the present invention, the steps (b) and (c) will be described in detail.

(B) Process: Process of forming an oblique vapor deposition film FIG. 8 is an apparatus configuration diagram showing an apparatus configuration of the oblique vapor deposition method in the method of manufacturing a liquid crystal device of the present invention. In FIG. 8, 701 is a vapor deposition source, 702 is a substrate, 703 is a substrate holder, 704 is a substrate normal, 705 is a vapor deposition angle, 706 is a vapor deposition distance, and 707 is a vapor deposition direction. The apparatus having the configuration shown in FIG. 8 is installed in a vacuum apparatus.

The vapor deposition source 701 introduces a material constituting the oblique vapor deposition film as a vapor deposition material, and heats the vapor deposition material by a method such as a resistance heating method or an electron beam vapor deposition method to perform vapor deposition.
Any material may be used as the evaporation source material as long as the inorganic alignment film to be formed can arrange liquid crystals in a certain azimuthal direction. For example, oxides such as silicon dioxide (SiOx), monoxide Silicon oxide such as silicon (SiO) (SiOx: about x = 1 to 2), magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), titanium oxide (TiO ₂ ), zirconium oxide ( ZrO ₂ ), chromium oxide (Cr ₂ O ₃ ), cobalt oxide (Co ₃ O ₄ ), iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ), and fluorides such as magnesium fluoride (MgF ₂ ), Alternatively, nitrides such as silicon nitride (SiNx), aluminum nitride (AlN), and the like can be given.

In the present invention, it is preferable to use silicon oxide (SiOx) such as silicon dioxide (SiO ₂ ) and silicon monoxide (SiO). The liquid crystal alignment state of these materials can be controlled by the formation conditions.

The form of the vapor deposition material is preferably a powder, granule, pellet or the like, but there is no particular limitation on the shape, size, etc. as long as the liquid crystal alignment can be controlled.
As the substrate 702, a substrate on which a pixel electrode and a counter electrode are formed, on which an oblique deposition film is formed, is used. The oblique vapor deposition film has a cross-sectional structure shown in FIG. 2, and the vapor deposition direction 707 shown in FIG. 8 corresponds to the vapor deposition direction 205 shown in FIG.

The substrate holder 703 is used for holding the substrate 702. By operating the substrate holder 703, the deposition angle 705 is defined.
In the present invention, the vapor deposition angle 705 is an angle formed by the substrate normal line 704 and a line segment (corresponding to the vapor deposition distance 706 in FIG. 8) connecting the vapor deposition source 701 and the center of the substrate 702. Although the deposition angle 705 depends on the configuration of the apparatus, it can usually be set between 0 ° and 90 °. When an oblique vapor deposition film used as an alignment film used for a liquid crystal element is produced, the angle is usually set in a range of 50 ° to 90 °. By setting the vapor deposition angle 705 within such a range, anisotropy due to the vapor deposition direction 707 is imparted to the oblique vapor deposition film, and liquid crystal molecules can be aligned in a certain direction.

  Furthermore, in the present invention, the deposition angle is preferably set in a range of 60 ° or more and less than 90 °. By setting to such a range, the pretilt angle control in the ion beam irradiation process performed in the process (c) described later can be performed in the range of 15 ° to 40 °.

  Further, when the oblique vapor deposition film is produced by such a method, the inclination angle 203 of the columnar structure constituting the oblique vapor deposition film shown in FIG. 2 is 60 ° or less. The tilt angle of the columnar structure of the oblique deposition film produced by the oblique deposition method is within the above range, so that the pretilt angle becomes 20 ° or more, and the pretilt angle control in the ion beam irradiation process described later is effectively performed. Can do.

  The thickness of the oblique deposition film shown in FIG. 2 is preferably 204 nm or more. By setting the film thickness within this range, it becomes possible to express a high pretilt angle of 20 ° or more while maintaining the orientation in the azimuth direction in one direction. This pretilt angle range is a pretilt angle range that can be suitably controlled in an ion beam irradiation process described later.

(C) Step: Step of Partially Irradiating Ion Beam Next, a step of partially irradiating the obliquely deposited film produced in step (b) with an ion beam will be described.

  FIG. 9 is an apparatus configuration diagram showing an ion beam irradiation method in the method of manufacturing a liquid crystal device according to the present invention. Here, 801 is an ion source, 802 is an ion beam irradiation angle, 803 is an oblique deposition film, and 804 is an ion beam irradiation direction.

  In the present invention, an ion beam is generated by introducing a gas containing an ion species to be irradiated using the ion source 801, and the substrate is irradiated with the generated ion beam at a certain angle. Here, the constant angle refers to the ion beam irradiation angle 802 in FIG. The ion beam irradiation angle 802 is determined in the same manner as the vapor deposition angle 705 in the oblique vapor deposition described in the step (b). That is, an angle formed by the substrate normal line 704 and a line segment connecting the center of the ion beam exit of the ion source 801 and the center of the substrate is the ion beam irradiation angle 802.

  The ion beam irradiation direction 804 can be set in a range including the vapor deposition direction 707 and the substrate normal 704 in the same plane. That is, the direction in which the columnar structure 202 shown in FIG. 2 is inclined, the ion beam irradiation direction 804, and the substrate normal line 704 are included in the same plane. By performing ion beam irradiation from such a direction, it is possible to control the pretilt angle while maintaining the liquid crystal alignment ability in the azimuth direction of the alignment film.

The ion beam irradiation method in the present invention is a method of defining the ion beam irradiation direction with reference to the growth direction of the columnar structure, and is the method shown in FIGS. That is, in order to effectively control the pretilt angle by ion beam irradiation, the tilt angle Θc of the columnar structure and the ion beam irradiation direction are the ion beam irradiation formed by the growth direction of the columnar structure and the ion beam irradiation direction. When the angle and theta _IB, based on the growth direction of the columnar _{structure, + 50 ° ≦ Θ IB ≦} + 100 ° ( where, theta _IB is 0 ° irradiation direction of the growth direction and the ion beam of the columnar structure is the same Θ _IB is an angle in which the ion beam irradiation direction is inclined in the direction of the inclination angle Θc of the columnar structure, and Θ _IB + is an angle in which the ion beam irradiation direction is the inclination angle Θc of the columnar structure. It is preferable that the angle is inclined in the opposite direction. By setting the above irradiation angle, the amount of change in the pretilt angle is increased as compared with the case where an irradiation angle outside the above range is selected, and as a result, the pretilt angle controllability is improved.

Although the ion beam irradiation method of FIG. 10 is a range not applicable in the present invention, it is shown for the purpose of explaining the sign of the ion beam irradiation angle. Step (b) in FIG. 10 is a method for forming the oblique vapor deposition film described above, and the vapor deposition angle 1005 is set on the substrate 1001 so that the columnar structure tilt angle Θc1006 after the columnar structure 1002 is formed becomes a predetermined angle. Then, an oblique vapor deposition film is formed by vapor deposition from the vapor deposition direction 1007. Next, as shown in FIG. 10C, the same arrangement as in the step of FIG. 10B, the same direction as the oblique deposition direction 1007, and the ion beam irradiation direction 1: 1008 and the substrate method. The ion beam is irradiated so that the angle formed by the line 1004 is larger than the deposition angle 1005. The sign of the ion beam irradiation angle Θ _IB 1009 at this time is −. That is, the ion beam irradiation angle Θ _IB 1009 is a negative sign (−) means that the ion beam irradiation direction is inclined in the direction of the inclination angle Θc of the columnar structure and from the growth direction 1007 of the columnar structure. The ion beam is irradiated from a shallow angle.

Next, an ion beam irradiation method shown in FIG. 11 that is within the scope of the present invention will be described. The process in FIG. 11B is the same as the oblique vapor deposition film forming process shown in the process in FIG. Next, as shown in FIG. 11C, the ion beam is irradiated from the ion beam irradiation direction 2: 1108. At this time, the ion beam irradiation angle Θ _IB 1109 is positive (+). The case where the ion beam irradiation angle is a negative sign (−) has been described above with reference to FIG. 10C, but the positive sign (+) is an angle region other than that.

  The ions that are the main components of the ion beam emitted from the ion source 801 shown in FIG. 9 are basically any ions as long as the pretilt angle of the oblique deposition film 803 can be controlled as a result of irradiation. However, irradiation with argon ions is particularly preferable. However, the present invention is not limited to argon ions, and ion beams can be irradiated using other ions as long as other ion species are more effective in controlling the pretilt angle.

  In the present invention, only the portion corresponding to the display area is irradiated with the ion beam. As a method for limiting the ion beam irradiation region, it is preferable to use a mask 1201 having an opening 1205 corresponding to the display region as shown in FIG. By using a mask having such a shape, it is possible to easily limit the irradiation region. However, if the ion beam irradiation region can be limited by a method other than the above, the method may be applied.

Hereinafter, the present embodiment will be described in more detail using examples, but the present invention is not limited to those described in the examples.
Example 1
In this example, an obliquely deposited film made of silicon oxide (SiOx) having a film thickness of 300 nm as an obliquely deposited film was formed on a part of the obliquely deposited film from the direction opposite to the inclined direction of the SiOx column by Ar ions. This is an example in which a liquid crystal device was manufactured by forming an inorganic alignment film by irradiating a beam.

Hereinafter, the steps (a) to (g) shown in FIG. 7 described in the method for manufacturing the liquid crystal device will be described.
(A) Process: Substrate Preparation Step First, a substrate on which a pixel electrode and a transfer electrode were formed and a substrate on which a counter electrode was formed were prepared. In this embodiment, the pixel electrode and the transfer electrode are reflective electrodes mainly composed of Al.

(B) Step: Step of forming an oblique vapor deposition film Next, an oblique vapor deposition film was formed on the substrate. The oblique vapor deposition film was set to a vapor deposition angle of 87.5 ° and a film thickness of 300 nm, and vapor deposition was performed using an apparatus having the configuration shown in FIG. At this time, a glass substrate for pretilt angle measurement was also set at the same time, and after pre-deposition, a pretilt angle measurement cell shown in FIG. 4 was prepared and the pretilt angle was measured. As the liquid crystal, a liquid crystal composition having a positive dielectric anisotropy (Merck: MLC-2050) was used. The pretilt angle at this time was 48.1 °.

(C) Process: The process of partially irradiating an ion beam Next, the ion beam was irradiated to a part of the oblique vapor deposition film | membrane board | substrate produced at the (b) process.
First, on each of the reflective electrode substrate and the counter electrode substrate, a mask in which only a portion corresponding to the display region portion was opened was installed. Next, using the ion beam irradiation apparatus having the configuration shown in FIG. 10, each substrate is arranged so that the ion beam is irradiated from the same direction as the growth direction of the SiOx column, that is, from the same direction as the vapor deposition direction in the oblique vapor deposition. Was installed. The ion source was an end-hole type ion source (Veeco), the irradiation angle was set to 45 °, the irradiation conditions were set to a cathode voltage of 300 V, and a cathode current of 10A. When ion beam emission is stabilized, the shutter provided between the ion source and the installation substrate is opened, and ion beam irradiation is started. The irradiation time was 5 minutes.

  At this time, as in the step (b), a pretilt angle measurement cell was installed at the same time, and the pretilt angle after ion beam irradiation was measured. The pretilt angle at that time was 35 ° for the ion beam irradiated portion and 44 ° for the non-irradiated portion.

  17 and 18 show the results of observing the surface structure and cross-sectional structure of the alignment film in the ion beam irradiated portion and the non-irradiated portion using a FE-SEM (scanning electron microscope S-5000H: manufactured by Hitachi High-Technologies Corporation). Show. FIG. 17 shows the microstructure of the obliquely deposited film in the ion beam non-irradiated part, and FIG. As a result, it was confirmed that the SiOx column was inclined in the same direction in both the irradiated part and the non-irradiated part.

  Next, when the film density of the ion beam irradiated part and the non-irradiated part was measured using spectroscopic ellipsometry, the film density of the ion beam irradiated part was 0.76, and the film density of the non-irradiated part was 0.21. It was found that the film density of the ion beam irradiated part was higher than that of the non-irradiated part.

(D) Process: Sealing agent application | coating and board | substrate bonding process Next, the liquid crystal cell for bend alignment formation is produced. A UV curable sealant is applied in a predetermined pattern shape on the substrate on which the reflective electrode is formed. Spacer beads having a diameter of 3 μm are mixed in the sealant.

  Next, the counter electrode substrate is placed in a predetermined direction and position on the reflective electrode forming substrate coated with the UV curable sealant. At the time of installation, the ion beam irradiation regions on both the substrates are installed so as to overlap each other, and an empty cell is manufactured by performing UV irradiation and substrate heating under predetermined conditions.

Step (e): Liquid crystal injection / liquid crystal cell sealing step Next, a liquid crystal material (MLC-2050 manufactured by Merck) is injected into the empty cell using a liquid crystal injection device. Thereafter, the LC cell is sealed using a UV curable sealant.

Step (f): Liquid crystal alignment treatment step Next, a realignment treatment of the liquid crystal layer is performed. The LC cell is heated above the nematic-isotropic phase transition temperature (89 ° C.) of the liquid crystal, and then slowly cooled.

(G) Process: Liquid crystal aligning process Next, a flexible cable is connected to the extraction electrode formed on the reflective electrode substrate via an anisotropic conductive adhesive film (ACF).

  Here, in order to confirm the alignment state of the liquid crystal, an alignment confirmation liquid crystal cell prepared by the same method as the above preparation method is prepared except that the counter electrode substrate is used instead of the reflective electrode substrate. When this liquid crystal cell is introduced between two polarizing plates having a crossed Nicols arrangement and observed, it is brightly colored in the area where ion beam irradiation is performed and black in the non-ion beam irradiation area. there were. From this, it can be confirmed that in the region irradiated with the ion beam, the liquid crystal layer forms a splay alignment, and in the non-ion beam irradiated region, a bend alignment is formed.

  A voltage is applied to the alignment confirmation liquid crystal cell to shift the splay alignment region to bend alignment. The state at this time is shown in FIG. The initial alignment state is shown in FIG. First, when a rectangular wave voltage having a frequency of 60 Hz is gradually applied to the transition electrode arranged around the display area and the pixel electrode in the display area, the transition to the bend orientation starts at an applied voltage of 1.3 V or more, and 1.5 V is applied. A few seconds later, the entire display area becomes bend alignment as shown in FIG.

  Thereafter, the voltage application was terminated and the sample was left in a state where no voltage was applied, and the change in the alignment state was observed, but as shown in FIG. 13C, the reverse transition to the splay alignment was not observed, and the bend alignment was Maintained.

  From the above results, in the region irradiated with the ion beam, although the splay alignment state is normally stable, the bend alignment region formed in the obliquely deposited film region not irradiated with the ion beam formed in the surrounding area. It can be confirmed that the bend orientation is maintained under the influence of the above.

Next, a uniaxial phase compensation plate is bonded onto the glass substrate of the liquid crystal cell. The phase compensation plate is installed so that the fast axis of the phase compensation plate is orthogonal to the fast axis of the liquid crystal cell.
When the liquid crystal cell is driven in this state and the voltage-reflectance characteristic (VR characteristic) is measured in the optical system arrangement as shown in FIG. 14, the graph shown in FIG. 15 is obtained, and the reflectance becomes maximum at 0V. It is possible to obtain a voltage-reflectance characteristic curve in which the reflectance becomes minimum near 5V.

  The change in the voltage-reflectance characteristics shown in FIG. 14 is due to the fact that the retardation (phase difference) of the liquid crystal layer changes with the applied voltage. In the liquid crystal device of this embodiment, the amount of retardation is large when the applied voltage is low, the retardation amount decreases as the applied voltage is increased, and the reflectance also decreases as the retardation amount decreases.

Comparative Example 1
This comparative example is an example of a liquid crystal device manufactured by the same method as in Example 1 except that no ion beam is irradiated.

  In this comparative example, since the ion beam is not irradiated, the pretilt angle is 48.1 ° in both the display region portion and the non-display region portion. When a parallel cell is manufactured, bend alignment is formed in both regions. Further, when the film density is measured by the same method as in Example 1, both the display area portion and the non-display area portion have the same value of 0.21.

When the voltage-reflectance characteristic was measured using the liquid crystal cell having the above-mentioned alignment state, a decrease in reflectance on the low voltage side was observed as compared with the case of Example 1.
Therefore, in the liquid crystal cell having the configuration of Comparative Example 1, it can be seen that the bend alignment can be formed with no voltage applied, but the reflectivity at 0 V decreases.

Comparative Example 2
This comparative example is an example of a liquid crystal device manufactured by the same method as in Example 1 except that the entire surface of the substrate is irradiated with an ion beam.

  In this comparative example, since the entire surface is irradiated with an ion beam without using a mask, the pretilt angle in both the display area portion and the non-display area portion is 28 °, which is lower than that of the original obliquely deposited film. When both are manufactured, splay alignment is formed in both regions. Further, when the film density is measured by the same method as in Example 1, both the display area portion and the non-display area portion have the same value.

  Further, FIG. 16 shows the change in orientation when a voltage is applied to the display region as in the case of the first embodiment. From the initial state (FIG. 16 (a)), a voltage higher than the transition voltage is applied to form a bend alignment (FIG. 16 (b)). And the bend orientation is not maintained (FIG. 16C).

From this, it can be confirmed that in the case of this comparative example, the bend alignment cannot be maintained in the state where no voltage is applied.
When the voltage-reflectance characteristics (VR characteristics) were measured, the reflectivity was not maximized at 0 V, and an extra voltage was required for the voltage required for the spray-bend transition. Accordingly, the voltage that minimizes the reflectance also increases.

Example 2
In this example, after forming an oblique vapor deposition film on the substrate in the same manner as in Example 1, only the substrate on which the reflective electrode was formed was irradiated with an argon ion beam on the display region using a mask, This is an example in which a liquid crystal device was manufactured without performing ion beam irradiation treatment on the counter electrode substrate. The film density of the ion beam irradiated part was 0.76, and the film density of the non-irradiated part was 0.21, indicating that the film density of the ion beam irradiated part was higher than that of the non-irradiated part.

  The conditions for forming the oblique deposition film are the same as in Example 1, the deposition angle is 87.5 °, and the film thickness is 300 nm. The ion beam irradiation condition to the reflective electrode substrate is the same as in Example 1. Irradiation is performed at an irradiation angle of 45 ° and irradiation conditions of 300 V and 10 A from the direction opposite to the column tilt direction.

  When the alignment confirmation cell was produced, only the display region irradiated with the ion beam was splayed in the same manner as in Example 1, and the other portions were bend aligned. Further, reverse transition after bend transition does not occur as in the first embodiment.

  The V-R characteristics are almost the same as in the case of Example 1.

  INDUSTRIAL APPLICABILITY The present invention can be used for a liquid crystal display element using an inorganic alignment film formed by a film formation method such as oblique vapor deposition, and a display device using the liquid crystal display element, for example, a projection display such as a projector. It can be used for devices, liquid crystal monitors, liquid crystal televisions and the like.

It is a conceptual diagram which shows the liquid crystal device of this invention. It is a conceptual diagram of the cross-sectional structure of the inorganic alignment film used for the liquid crystal device of this invention. It is a conceptual diagram which shows the splay alignment state used for the liquid crystal device of this invention. It is a conceptual diagram which shows the bend alignment state used for the liquid crystal device of this invention. It is a conceptual diagram which shows the pretilt angle in the liquid crystal device of this invention. It is a conceptual diagram of the cross-sectional structure of the boundary part which corresponds to the display area part and non-display area part of the liquid crystal device of this invention. It is process drawing explaining each process in the manufacturing method of the liquid crystal device of this invention. It is an apparatus block diagram which shows the apparatus structure of the oblique vapor deposition method in the manufacturing method of the liquid crystal device of this invention. It is an apparatus block diagram which shows the ion beam irradiation method in the manufacturing method of the liquid crystal device of this invention. It is a conceptual diagram which shows an example of the ion beam irradiation direction with respect to an oblique vapor deposition film in the manufacturing method of the liquid crystal device of this invention. It is a conceptual diagram which shows an example of the ion beam irradiation direction with respect to an oblique vapor deposition film in the manufacturing method of the liquid crystal device of this invention. It is a conceptual diagram which shows the mask shape used for the manufacturing method of the liquid crystal device of this invention. It is an example which shows the orientation change of the display area before and behind voltage application in the liquid crystal device of this invention. It is an apparatus block diagram of the measurement system used for the voltage-reflectance characteristic measurement of the liquid crystal device of this invention. It is a graph of the voltage-reflectance characteristic in the liquid crystal device of the present invention. It is an example which shows the orientation change of the display area before and behind voltage application in the liquid crystal device of this invention. It is an electron micrograph which shows the structure of the oblique vapor deposition film | membrane of the ion beam non-irradiation part in the liquid crystal device of this invention. It is an electron micrograph which shows the structure of the oblique vapor deposition film | membrane of an ion beam irradiation part in the liquid crystal device of this invention.

Explanation of symbols

101, 305 Pixel electrode 102, 601 Transfer electrode 103 Sealing agent 104 Sealing part 105 Extraction electrode 106, 1204, 1301, 1701, 1607 Display area part 107, 1302, 1702, 1606 Non-display area part 108 Display area part and non-display Region part boundaries 201, 702, 901, 1203 Substrate 202 Columnar structure 203 Inclination angle of columnar structure 204 Film thickness 205 Deposition direction 206 Void 301 Upper substrate 302 Counter electrode 303 Inorganic alignment film A
304 Inorganic alignment film A ′
306 Lower substrate 307, 602 Liquid crystal layer A
401 Inorganic alignment film B
402 Inorganic alignment film B ′
403, 603 Liquid crystal layer B
501 Pretilt angle θp
502 Liquid crystal molecules 503 Alignment film 504 Glass substrate 505 Alignment processing direction 701 Deposition source 703 Substrate holder 704, 908 Substrate normal 705, 904 Deposition angle 706 Deposition distance 707, 903 Deposition direction 801 Ion source 802 Ion beam irradiation angle 803, 902, 1603 Obliquely deposited film 804 Ion beam irradiation direction 905, 1604 Inorganic alignment film irradiated with ion beam 906 Ion beam irradiation direction 1
907 Ion beam irradiation angle 1
1201, 1605 Mask 1202 Inorganic alignment film 1205 Opening 1401 Half mirror 1402 Phase plate 1403 Liquid crystal device 1404 Light source 1405 Polarizing plate 1
1406 Polarizing plate 2
1601 Electrode / circuit forming substrate 1602 Counter electrode substrate 1608 Sealing portion 1609 Liquid crystal layer 1
1610 Liquid crystal layer 2
1611 Flexible cable

Claims (14)

  A liquid crystal device comprising: a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy; and a pair of substrates through which at least one substrate transmits light, sandwiching and facing the liquid crystal layer, A display region portion in which a plurality of pixel electrodes are disposed on one of the substrates, a non-display region portion other than the display region portion is disposed, and a counter electrode is disposed on the other substrate, An inorganic alignment film is disposed on the liquid crystal layer side of the pair of substrates, and the inorganic alignment film disposed on at least one of the substrates has different film densities in the display region portion and the non-display region portion. Liquid crystal device.   The liquid crystal device according to claim 1, wherein a film density of the inorganic alignment film in the display region portion is larger than a film density of the inorganic alignment film in the non-display region.   The inorganic alignment film is formed of a columnar structure made of an inorganic material, and the arrangement direction of the columnar structure with respect to the substrate in the azimuth direction is the same direction in the display region portion and the non-display region portion. Item 3. The liquid crystal device according to item 1 or 2.   4. The liquid crystal device according to claim 1, wherein the material constituting the inorganic alignment film is silicon oxide.   5. The liquid crystal layer according to claim 1, wherein the alignment state during the display operation is bend alignment, and the retardation of the liquid crystal layer is controlled by a voltage applied between the pixel electrode and the counter electrode. The liquid crystal device according to any one of the above items.   6. The liquid crystal device according to claim 1, wherein in the liquid crystal layer in the non-display region portion, the alignment state of the liquid crystal layer when no voltage is applied is bend alignment.   The liquid crystal device according to claim 1, wherein an electrode that does not contribute to display is disposed in the non-display area portion.   The shape of the display area part is a rectangle, and an electrode which does not contribute to display arranged in the non-display area part is formed along each side of the display area part. The liquid crystal device according to any one of the above items.   A method of manufacturing a liquid crystal device comprising: a liquid crystal layer made of nematic liquid crystal having positive dielectric anisotropy; and a pair of substrates through which at least one substrate transmits light, sandwiching and facing the liquid crystal layer A step of forming an inorganic alignment film by obliquely vapor-depositing an inorganic material on a substrate, and irradiating a partial region of the inorganic alignment film with an ion beam at a fixed irradiation angle, thereby the inorganic alignment film A method of manufacturing a liquid crystal device, comprising: forming a display region portion and a non-display region portion having different film densities.   The method for manufacturing a liquid crystal device according to claim 9, wherein in the step of forming the inorganic alignment film by oblique deposition, a deposition angle is 60 ° or more and less than 90 °. The inorganic alignment film formed in the step of forming the inorganic alignment film has a columnar structure including the inorganic material, and the ion beam irradiation in the step of irradiating a partial region of the inorganic alignment film with the ion beam. The direction is parallel to a plane including the substrate normal and the vapor deposition direction in the oblique deposition, the inclination angle Θc of the columnar structure with respect to the substrate normal is 20 ° or more, and the inclination angle of the columnar structure is The reference ion beam irradiation angle Θ _IB is + 50 ° ≦ Θ _IB ≦ + 100 ° (however, ΘIB is positive when the ion beam irradiation direction approaches the substrate normal from the tilt angle of the columnar structure). 11. The method of manufacturing a liquid crystal device according to claim 9 or 10, wherein:   The method of manufacturing a liquid crystal device according to claim 9, wherein the ion beam is an ion beam made of argon ions.   The method of irradiating an ion beam to a partial region of the oblique deposition film is a method of irradiating an ion beam using a mask having an opening. A manufacturing method of the liquid crystal device according to the description.   14. The method of manufacturing a liquid crystal device according to claim 13, wherein the size of the opening of the mask is a size including at least the display region.