JP6486155B2 - Liquid crystal display element - Google Patents

Description

  The present invention relates to a liquid crystal display element.

As a driving method of the liquid crystal display element, there are methods such as TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal) and the like.
Among them, the IPS method changes the alignment direction of the liquid crystal molecules by applying an electric field in a direction parallel to the substrate surface (lateral direction) to the liquid crystal molecules filled between the two substrates, thereby performing display. Is going. Such an IPS liquid crystal display element has excellent visual characteristics and is applied to a wide range of devices such as mobile phones and televisions.

  In the existing liquid crystal display element, the alignment direction of the liquid crystal molecules is forced so that the liquid crystal molecules are aligned along a predetermined direction when no electric field is applied.

  As a method of forcing the alignment direction of liquid crystal molecules, an alignment film made of polyimide or the like is formed on a substrate, and the surface of the alignment film is rubbed in a predetermined direction with a cloth such as rayon or cotton (rubbing method) Is used to generate anisotropy on the surface of the polyimide film (photo-alignment method). By these treatments, the liquid crystal molecules are strongly bound to the substrate surface and aligned in a certain direction.

  On the other hand, a method has also been proposed in which the orientation direction of liquid crystal molecules is directed to an arbitrary direction by an external field (electric field, magnetic field, etc.) and the state is maintained (memory). In order to realize such an operation, it is necessary to eliminate alignment forcing (anchoring) on the substrate surface. Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-215421) has been proposed as a related technology for a configuration that weakens anchoring. In the configuration disclosed in Patent Document 1, in a liquid crystal cell in which a polymer brush is formed on a substrate subjected to a planarization process, and a liquid crystal is sandwiched between the substrates, the Tg (glass transition temperature) of the coexisting portion of the polymer brush and the liquid crystal. ) And a temperature at which the shape of the coexisting part can be freely changed, thereby realizing a zero-plane anchoring state.

In the existing liquid crystal display element, the liquid crystal molecules in the liquid crystal layer return to the original orientation direction of the liquid crystal molecules displaced by the electric field when the application of the electric field is stopped.
At this time, in the configuration in which the liquid crystal molecules are aligned in a certain direction by applying a strong binding force to the liquid crystal molecules with an alignment film formed by a rubbing method or a photo-alignment method, when the application of the electric field is stopped, The alignment direction of the displaced liquid crystal molecules quickly returns to the original due to the strong binding force of the alignment film.
On the other hand, in the configuration described in Patent Document 1, since the binding force by the alignment film is weak, it takes time for the alignment direction of the liquid crystal molecules to return to the original. Therefore, high display responsiveness is desired.

  According to the present invention, a light source that emits light, a first substrate on which a first alignment film is formed, and a second alignment film that is disposed to face each other with a space between the first alignment film are formed. A second liquid crystal layer, a liquid crystal layer disposed between the first alignment film and the second alignment film, and transmitting or blocking the light by driving liquid crystal molecules; A driving electrode layer that is provided on one of the substrate and the second substrate and applies an electric field in a direction along the first substrate and the second substrate to the liquid crystal molecules, and the first substrate And a return electrode layer that is provided on one of the second substrates and applies a return electric field to the liquid crystal molecules in a direction that intersects the electric field in a direction along the first substrate and the second substrate. And the liquid crystal layer includes the second liquid crystal layer in a state where the electric field is applied. On the alignment film side, the liquid crystal molecules maintain a state of being aligned in a predetermined initial alignment direction, and on the first alignment film side, the alignment direction of the liquid crystal molecules is on the surface of the second substrate. The liquid crystal molecules are arranged in a spiral shape from the second alignment film side to the first alignment film side by changing from the initial alignment direction to a direction corresponding to the electric field in a parallel plane. A liquid crystal display element is provided.

  The drive electrode layer displaces the alignment direction of the liquid crystal molecules by the electric field from the alignment direction of the liquid crystal molecules in a state where the electric field is not applied, and the return electrode layer generates the liquid crystal molecules by the return electric field. The orientation direction may be displaced so as to return to the orientation direction of the liquid crystal molecules in a state where the electric field is not applied.

  The plurality of electrode lines constituting the return electrode layer may be formed to extend in the intersecting direction with respect to the plurality of electrode lines constituting the drive electrode layer.

  The first alignment film may have a restraining force that restrains the alignment direction of the liquid crystal molecules when the electric field is applied to be smaller than that of the second alignment film.

  The displacement angle in the alignment direction of the liquid crystal molecules of the liquid crystal layer may gradually increase from the second alignment film side to the first alignment film side in the state where the electric field is applied.

  Further, the liquid crystal molecules by the electric field generated by applying a predetermined voltage between the liquid crystal molecules located on the first alignment film side and the liquid crystal molecules located on the second alignment film side. The difference in the displacement angle in the alignment direction may be 0 ° or more and 90 ° or less.

  In addition, a polymer brush may be formed on the first substrate as the first alignment film.

  Further, the drive electrode layer is composed of a plurality of electrode lines arranged on the first substrate or the second substrate surface, and the orientation direction of the liquid crystal molecules when the electric field is not applied is determined by the electrode lines. May be parallel or orthogonal to the continuous direction.

  Further, the drive electrode layer is composed of a plurality of electrode lines arranged on the first substrate or the second substrate, and when the electric field is not applied, the alignment direction of the liquid crystal molecules is You may make it incline with respect to the continuous direction.

  Further, the dielectric anisotropy of the liquid crystal molecules may be negative.

  Further, when switching between the application of the electric field in the drive electrode layer and the application of the return electric field in the return electrode layer, the application of the return electric field is started prior to ending the application of the electric field. Also good.

  Further, the dielectric anisotropy of the liquid crystal molecules may be positive.

  Further, when switching between the application of the electric field in the drive electrode layer and the application of the return electric field in the return electrode layer, a time lag may be set constant.

  According to the present invention, the following effects can be obtained.

  That is, it is possible to perform display with higher transmittance and higher display responsiveness while driving liquid crystal molecules with a low voltage.

It is sectional drawing which shows schematic structure of the liquid crystal display shown as 1st Embodiment of this invention. FIG. 3 is a diagram showing a distribution of alignment directions of liquid crystal molecules in a liquid crystal panel of the liquid crystal display shown as the first embodiment when a liquid crystal having positive dielectric anisotropy is used and an electric field is applied. In the liquid crystal panel of the liquid crystal display shown as the said 1st Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a liquid crystal with positive dielectric anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as said 1st Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which applied the electric field using the liquid crystal with positive dielectric anisotropy. In the liquid crystal display element of the liquid crystal display shown as the first embodiment, a liquid crystal having positive dielectric anisotropy is used, and the relationship between the electrode line of the return electrode and the alignment direction of the liquid crystal molecules when no return electric field is applied. FIG. In the liquid crystal display element of the liquid crystal display shown as the first embodiment, the relationship between the electrode line of the return electrode and the alignment direction of the liquid crystal molecules in a state where a return electric field is applied using a liquid crystal having a positive dielectric anisotropy. FIG. It is sectional drawing which shows the example of the polymer brush formed in the board | substrate as a weak anchoring orientation film. In the liquid crystal panel of the liquid crystal display shown as 2nd Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a liquid crystal with positive dielectric anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as the second embodiment, another example of the relationship between the electrode line and the alignment direction of the liquid crystal molecules in a state where an electric field is applied using a liquid crystal having positive dielectric anisotropy is shown. FIG. In the liquid crystal panel of the liquid crystal display shown as 3rd Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a liquid crystal with positive dielectric anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as the third embodiment, another example of the relationship between the electrode line and the orientation direction of the liquid crystal molecules in a state where an electric field is applied using a liquid crystal having positive dielectric anisotropy is shown. FIG. It is sectional drawing which shows schematic structure of the liquid crystal display shown as 4th Embodiment of this invention. It is a figure which shows the distribution of the orientation direction of the liquid crystal molecule in the state which applied the electric field in the liquid crystal panel of the liquid crystal display shown as the said 4th Embodiment using the liquid crystal with a negative dielectric constant anisotropy. In the liquid crystal panel of the liquid crystal display shown as the said 4th Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a negative dielectric constant anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as the said 4th Embodiment, it is a figure which shows the relationship between the electrode line in the state which applied the electric field using the liquid crystal with a negative dielectric constant anisotropy, and the orientation direction of a liquid crystal molecule. In the liquid crystal display element of the liquid crystal display shown as the fourth embodiment, a liquid crystal having a negative dielectric anisotropy is used, and the relationship between the electrode line of the return electrode and the alignment direction of the liquid crystal molecules when no return electric field is applied. FIG. In the liquid crystal display element of the liquid crystal display shown as the fourth embodiment, a liquid crystal having a negative dielectric anisotropy is used, and the relationship between the electrode line of the return electrode and the alignment direction of the liquid crystal molecules in a state where a return electric field is applied. FIG. In the liquid crystal panel of the liquid crystal display shown as 5th Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a negative dielectric constant anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as the fifth embodiment, another example of the relationship between the electrode line and the alignment direction of the liquid crystal molecules in a state where an electric field is applied using a liquid crystal having a negative dielectric anisotropy is shown. FIG. In the liquid crystal panel of the liquid crystal display shown as 6th Embodiment, it is a figure which shows the relationship between the electrode line and the orientation direction of a liquid crystal molecule in the state which uses a negative dielectric constant anisotropy and does not apply an electric field. In the liquid crystal panel of the liquid crystal display shown as the sixth embodiment, another example of the relationship between the electrode line and the orientation direction of the liquid crystal molecules in a state where an electric field is applied using a liquid crystal having a negative dielectric anisotropy is shown. FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

There are two types of liquid crystal: a positive type having a positive dielectric anisotropy and a negative type having a negative dielectric anisotropy. The positive type liquid crystal has a large dielectric property in the major axis direction of the liquid crystal molecules and is small in a direction perpendicular to the major axis direction. The negative type has a small dielectric property in the major axis direction of the liquid crystal molecules and is large in a direction perpendicular to the major axis direction. In this embodiment, an example using positive liquid crystal will be described.
In addition, as an alignment film for controlling the alignment direction of liquid crystal molecules, a strong anchoring alignment film having a strong force for restricting the alignment direction of liquid crystal molecules and a weak anchoring alignment film having a low force for restricting the alignment direction of liquid crystal molecules. There is. The present invention employs a strong anchoring alignment film on one of the alignment films facing each other and a weak anchoring alignment film on the other, and a weak anchoring on both alignment films facing each other. The target is a double-sided weak anchoring type employing an alignment film. In the following, an embodiment using the single-sided weak anchoring format will be described.
FIG. 1 is a cross-sectional view showing a schematic configuration of the liquid crystal display shown as the first embodiment of the present invention. FIG. 2 is a diagram showing a distribution of alignment directions of liquid crystal molecules in a liquid crystal panel of the liquid crystal display shown as the first embodiment when a liquid crystal having positive dielectric anisotropy is used and an electric field is applied. FIG. 3 shows the relationship between the electrode line and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the first embodiment, using a liquid crystal with positive dielectric anisotropy and no electric field applied. FIG. FIG. 4 shows the relationship between the electrode lines and the orientation directions of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the first embodiment using a liquid crystal having positive dielectric anisotropy and applying an electric field. FIG. FIG. 5 shows the liquid crystal display element of the liquid crystal display shown as the first embodiment using a liquid crystal having positive dielectric anisotropy, and the orientation direction of the electrode lines of the return electrode and the liquid crystal molecules when no return electric field is applied. It is a figure which shows the relationship. FIG. 6 shows the liquid crystal display element of the liquid crystal display shown as the first embodiment using liquid crystal having positive dielectric anisotropy and the orientation direction of the electrode lines of the return electrode and the liquid crystal molecules in the state where the return electric field is applied. It is a figure which shows the relationship.
As shown in FIGS. 1 and 2, the liquid crystal display 10 includes a liquid crystal panel (liquid crystal display element) 11 and a backlight unit 12 that provides light to the liquid crystal panel 11.

  The backlight unit 12 uniformly irradiates light input from a light source (not shown) provided on the back surface of the liquid crystal panel 11 from the back surface 11r side to the front surface 11f side of the liquid crystal panel 11. For example, the backlight unit 12 propagates light input from a light source (not shown) provided at one end thereof in a direction parallel to the surface 11f of the liquid crystal panel 11 and transmits the propagated light to the liquid crystal panel. A so-called edge light type that emits light from the back surface 11r side to the front surface 11f side can be used. The backlight unit 12 is a so-called direct type that irradiates light input from a light source provided on the back surface 11r side of the liquid crystal panel 11 from the back surface 11r side to the front surface 11f side of the liquid crystal panel 11. You can also

  The liquid crystal panel 11 includes a substrate (second substrate) 13A, a substrate (first substrate) 13B, polarizing plates 14A and 14B, a drive electrode layer 15, and a strong anchoring alignment film (second alignment film) 16. A weak anchoring alignment film (first alignment film) 17, a liquid crystal layer 18, and a return electrode layer 19.

  The substrates 13A and 13B are each made of a substrate such as glass or resin, and are arranged in parallel with each other at a predetermined interval.

The polarizing plate 14 </ b> A is provided on the side facing the backlight unit 12 or on the side opposite to the backlight unit 12 in the substrate 13 </ b> A disposed on the backlight unit 12 side.
The polarizing plate 14 </ b> B is provided on the side opposite to the backlight unit 12 or the side facing the backlight unit 12 in the substrate 13 </ b> B disposed on the side away from the backlight unit 12.
These polarizing plates 14A and 14B have their transmission axis directions orthogonal to each other. For example, the transmission axis direction of one polarizing plate 14A is set to the direction Y along the substrate 13B, and the transmission axis direction of the other polarizing plate 14B is set to the direction X perpendicular to the direction Y along the substrate 13B. ing.

The drive electrode layer 15 is provided on one of the substrates 13A and 13B. In this embodiment, the drive electrode layer 15 is provided on the substrate 13A on the backlight unit 12 side on the side away from the backlight unit 12.
The drive electrode layer 15 is formed by arranging a plurality of electrode lines 20A in parallel along the surface of the substrate 13A. Here, as shown in FIG. 3, each electrode line 20 </ b> A is formed in a linear shape such that its long axis direction extends along the direction Y in a plane parallel to the surface of the substrate 13 </ b> A, for example. The drive electrode layer 15 has such electrode lines 20A arranged in parallel at regular intervals along a direction X orthogonal to the direction Y in a plane parallel to the surface of the substrate 13A.

  As shown in FIGS. 2 and 4, in such a drive electrode layer 15, when a preset voltage is applied to each electrode line 20 </ b> A of the drive electrode layer 15, these electrode lines 20 </ b> A are adjacent to each other. An electric field E is generated in a direction connecting adjacent electrode lines 20A, that is, in this embodiment, a direction X parallel to the substrate 13B.

  The strong anchoring alignment film 16 is provided on one of the substrates 13A and 13B. In this embodiment, the strong anchoring alignment film 16 is formed on the substrate 13A on the backlight unit 12 side on the side away from the backlight unit 12.

  The weak anchoring alignment film 17 is provided on the other of the substrates 13A and 13B. In this embodiment, the weak anchoring alignment film 17 is formed on the side facing the backlight unit 12 in the substrate 13B on the side separated from the backlight unit 12.

  The liquid crystal layer 18 is formed by filling a large number of liquid crystal molecules Lp between the strong anchoring alignment film 16 and the weak anchoring alignment film 17. The liquid crystal layer 18 is driven by changing the alignment direction of the liquid crystal molecules Lp by an electric field E generated by applying a voltage to each electrode line 20 </ b> A constituting the drive electrode layer 15. By changing the orientation of the liquid crystal molecules Lp in this manner, the liquid crystal layer 18 partially transmits or blocks the light supplied from the backlight unit 12 to generate a display image.

  As shown in FIG. 1, the return electrode layer 19 is provided on one of the substrates 13A and 13B. In this embodiment, the return electrode layer 19 is provided on the side facing the backlight unit 12 in the substrate 13 </ b> B on the side separated from the backlight unit 12.

  As shown in FIG. 5, the return electrode layer 19 is formed by arranging a plurality of electrode lines 21 along the surface of the substrate 13B. Here, each electrode line 21 is formed so that the major axis direction thereof is aligned with, for example, the direction X along the substrate 13B. That is, each electrode line 21 is provided substantially orthogonal to each electrode line 20 </ b> A constituting the drive electrode layer 15.

  The return electrode layer 19 is formed by arranging such electrode lines 21 in parallel at regular intervals along a direction Y orthogonal to the direction X along the substrate 13B.

  As shown in FIG. 6, in the return electrode layer 19, when a preset voltage is applied to each electrode line 21, a direction connecting the electrode lines 21 adjacent to each other between the electrode lines 21 adjacent to each other. That is, in this embodiment, the return electric field Er in the direction Y is generated. The return electric field Er changes the alignment direction of the liquid crystal molecules Lp of the liquid crystal layer 18 as will be described later.

  The return electrode layer 19 is applied with a predetermined applied voltage when the orientation of the liquid crystal molecules Lp whose orientation direction has been changed by the electric field E applied by the drive electrode layer 15 is returned to the initial state where the electric field E is not applied. As a result, a return electric field Er is generated.

That is, in this liquid crystal display 10, while the liquid crystal molecules Lp of the liquid crystal layer 18 are driven by the electric field E applied by the drive electrode layer 15, the alignment direction of the liquid crystal molecules Lp is returned to the initial state where the electric field E is not applied. It is sometimes controlled to apply an applied voltage to the return electrode layer 19.
As described above, the applied voltage is applied to the return electrode layer 19 when, for example, the liquid crystal display 10 is shut down or “black” is displayed in each pixel. In addition, in order to continuously drive the liquid crystal molecules Lp, a voltage is applied to each electrode line 20 of the drive electrode layer 15 every minute fixed time, but every time a voltage is applied to the electrode line 20 once. A voltage may be applied to the electrode line 21 of the return electrode layer 19 to return the liquid crystal molecules Lp to the initial state.

Here, the strong anchoring alignment film 16 and the weak anchoring alignment film 17 are different from each other in the alignment restraining force that restricts the alignment direction of the liquid crystal molecules Lp.
That is, as shown in FIG. 2, the strong anchoring alignment film 16 has the long axis of the liquid crystal molecules Lp on the strong anchoring alignment film 16 side in the liquid crystal layer 18 even when a voltage is applied to generate the electric field E. In the initial alignment state in which the direction is substantially matched with the alignment direction in the plane parallel to the surfaces of the substrates 13A and 13B (direction Y in FIG. 2), that is, in the alignment treatment direction (direction Y) of the strong anchoring alignment film 16. The initial alignment state along is maintained.
On the other hand, in the weak anchoring alignment film 17, when the applied voltage becomes equal to or higher than the threshold voltage when the electric field E is generated by applying a voltage, on the weak anchoring alignment film 17 side of the liquid crystal layer 18, The liquid crystal molecules Lp are released from the restraint of the weak anchoring alignment film 17. The alignment direction of the liquid crystal molecules Lp changes from the initial alignment direction (direction Y in FIG. 2) in a plane parallel to the surfaces of the substrates 13A and 13B according to the magnitude of the applied voltage.

  As described above, in the strong anchoring alignment film 16 and the weak anchoring alignment film 17, when the electric field E is applied, the liquid crystal molecules Lp are strongly anchored alignment on the strong anchoring alignment film 16 side of the liquid crystal layer 18. While the alignment direction is maintained while receiving the alignment forcing by the film 16, the alignment forcing by the weak anchoring alignment film 17 is removed from the weak anchoring alignment film 17 side, and the alignment direction of the liquid crystal molecules Lp is changed. Change.

  As a result, in the liquid crystal layer 18, the alignment direction of the liquid crystal molecules Lp when the electric field E equal to or higher than the threshold is applied is different between the strong anchoring alignment film 16 side and the weak anchoring alignment film 17 side. As a result, the liquid crystal molecules Lp gradually shift from the strong anchoring alignment film 16 side toward the weak anchoring alignment film 17 side, and the displacement amount of the alignment angle with respect to the initial alignment direction gradually increases, and the liquid crystal molecules Lp transition to the twisted alignment state. When the electric field strength reaches a certain value, the liquid crystal molecules Lp in the vicinity of the weak anchoring alignment film 17 are aligned in a direction parallel to the direction of the electric field E. That is, the alignment state is twisted by 90 ° from the strong anchoring alignment film 16 side toward the weak anchoring alignment film 17 side.

  The alignment state of the liquid crystal layer 18 when the voltage is applied is the same as the alignment state of the liquid crystal when no voltage is applied in the TN mode. Therefore, the optical design of the liquid crystal panel 11 is performed so as to satisfy ΔnP >> λ (Δn is the refractive index anisotropy of the liquid crystal, P is the helical pitch of the liquid crystal, and λ is the wavelength of light), that is, the Morgan condition (Mougain Condition). For example, an optical rotation effect can be generated in the liquid crystal layer 18.

  Further, the following Gooch-Tarry equation (1) is known as an equation for giving the light transmittance T in a TN liquid crystal panel.

  Here, u = dΔn / λ · π / θ, d is the cell gap (thickness of the liquid crystal layer 18), θ is the twist angle of the liquid crystal molecules Lp, and in this embodiment, strong anchoring during voltage application is performed. This corresponds to the difference in angle between the alignment directions of the liquid crystal molecules on the alignment film 16 side and the liquid crystal molecules on the weak anchoring alignment film 17 side. In the present embodiment, since θ = π / 2, u = 2dΔn / λ.

  In the liquid crystal panel 11, positive type liquid crystal molecules Lp are used, the polarizing plates 14A and the polarizing plates 14B are arranged in crossed Nicols in which the transmission axis directions are orthogonal to each other, and the transmission axis direction of the polarizing plate 14A is the electric field E Is set so as to coincide with the alignment treatment direction (direction Y in FIG. 1) with respect to the strong anchoring alignment film 16 for regulating the alignment direction of the liquid crystal molecules Lp in a state where no is applied. In the state where the electric field E is not applied, the liquid crystal molecules Lp are uniformly aligned in the alignment treatment direction with respect to the strong anchoring alignment film 16, so that the linearly polarized light incident on the liquid crystal layer 18 maintains the polarization state and the polarization plane. The light is emitted from the liquid crystal panel 11 as it is. At this time, since the polarization direction of the linearly polarized light incident on the liquid crystal layer 18 (direction Y in FIG. 1) and the transmission axis direction of the polarizing plate 14B are orthogonal, light from the backlight unit 12 side passes through the polarizing plate 14B. Cannot penetrate.

  On the other hand, in the state where the electric field E is applied, the liquid crystal molecules Lp have the major axis direction on the strong anchoring alignment film 16 side as described above, and the alignment treatment direction of the strong anchoring alignment film 16 (direction Y in FIG. 2). The initial alignment state along is maintained. On the other hand, on the weak anchoring alignment film 17 side, the application direction of the electric field E exceeding the threshold value causes the alignment direction of the liquid crystal molecules Lp to start to change in a plane parallel to the substrate 13B, and the electric field strength reaches a certain value. Sometimes, the major axis direction of the liquid crystal molecules Lp is along the direction parallel to the electric field E, that is, the direction X parallel to the substrate 13B. At this time, the optical condition of the liquid crystal panel 11 is designed so that the Morgan condition is satisfied and the formula (2) takes the maximum value, so that the linearly polarized light incident on the liquid crystal layer 18 remains in the polarization state. The polarization plane rotates (rotates) by 90 °, passes through the polarizing plate 14B, and exits from the liquid crystal panel 11. Accordingly, light incident on the liquid crystal panel 11 from the backlight unit 12 side can be transmitted with maximum efficiency. That is, the transmittance T at the time of voltage application in the present embodiment can be maximized (50% when the absorption of the polarizing plate is assumed to be 0). Here, since the response speed generally decreases as the cell gap d increases, the optical design of the liquid crystal panel selects a so-called first minimum condition from a plurality of conditions in which Equation (2) takes the maximum value. It is preferable to do this.

As described above, in the liquid crystal panel 11 of the present embodiment, the positive liquid crystal molecules Lp are used, the polarizing plates 14A and 14B are arranged in a crossed Nicol state, and the transmission axis direction of the polarizing plate 14A determines the electric field E. It is set to coincide with the alignment treatment direction for the strong anchoring alignment film 16 for regulating the alignment direction of the liquid crystal molecules Lp in the non-application state (direction Y in FIG. 1). According to such a configuration, when a predetermined electric field E equal to or higher than the threshold is applied to the liquid crystal panel 11, the liquid crystal molecules Lp are initially directed from the strong anchoring alignment film 16 side toward the weak anchoring alignment film 17 side. The amount of displacement in the alignment direction with respect to the alignment direction gradually increases, and transitions to a helically twisted alignment state. Thereby, the light passing through the polarizing plate 14A from the backlight unit 12 side is polarized along the distribution in the alignment direction of the liquid crystal molecules Lp from the strong anchoring alignment film 16 side to the weak anchoring alignment film 17 side. Changes and is emitted through the polarizing plate 14B on the opposite side.
As described above, the liquid crystal panel 11 employs an IPS driving method in which the liquid crystal molecules Lp are displaced in a plane along the surfaces of the substrates 13A and 13B as a liquid crystal driving method. Perform on / off control.

  By the way, as shown in FIG. 5, after the application of the electric field E is stopped from the state where the electric field E is applied, when the return electric field Er is applied in the return electrode layer 19 as shown in FIG. The alignment direction is changed between the electrode lines 21 and 21 adjacent to each other so that the major axis direction coincides with the direction Y intersecting the electrode line 21. Thereby, the alignment direction of the liquid crystal molecules Lp returns to the initial alignment state.

  When the switching timing from application of the electric field E to application of the return electric field Er is short, a short circuit occurs between the electrode line 20A of the drive electrode layer 15 and the electrode line 21 of the return electrode layer 19, and the substrates 13A and 13B. There is a possibility that a short-circuit electric field Et in the direction connecting the two will occur. When the short-circuit electric field Et occurs, the positive type liquid crystal molecules Lp rise in the direction in which the major axis direction is orthogonal to the surfaces of the substrates 13A and 13B, so that the liquid crystal molecules Lp cannot be completely returned to the initial alignment state. There is a possibility that light from the 12 side leaks through the polarizing plate 14B.

Therefore, when using positive type liquid crystal molecules Lp, a certain time lag is set so that the electric field E disappears completely from the state in which the electric field E is applied until the application of the return electric field Er is started. Is preferred. That is, the application of the return electric field Er is started after a preset standby time has elapsed from the timing when the application of the electric field E is stopped.
Thereby, generation | occurrence | production of the short circuit electric field Et can be prevented and it can prevent that the liquid crystal molecule Lp rises.

  By the way, the strong anchoring alignment film 16 as described above is formed as follows, for example. First, an alignment film made of polyimide or the like is formed on the substrate 13A. Thereafter, a roller wound with a cloth made of rayon, cotton, or the like is rotated with the rotation speed and the distance between the roller and the substrate 13A being kept constant, and the surface of the alignment film is rubbed in a predetermined direction (rubbing method). Alternatively, anisotropy is generated on the surface of the alignment film made of polyimide by irradiating polarized ultraviolet rays (photo-alignment method). The strong anchoring alignment film 16 in which the alignment direction is set by the rubbing method, the photo-alignment method, or the like applies a stronger alignment forcing force than the weak anchoring alignment film 17 to the liquid crystal molecules Lp.

  As the weak anchoring alignment film 17, for example, a film formed with a polymer brush can be used. The polymer brush is formed of a graft polymer chain having one end fixed to the surface of the substrate 13B and the other end extending in a direction away from the surface of the substrate 13B. Such a graft polymer chain may be generated by stretching from the substrate 13B side, or a polymer chain having a predetermined length may be attached to the substrate 13B in advance.

一般式（１）において、ＸはＨ又はＣＨ_３であり、ｍは正の整数であって、ポリマーブラシのＴｇ（ガラス転移温度）が−５℃以下であるものである。 Below, a specific example of a polymer brush is shown.
A polymer brush is represented by the following general formula (1), for example.

In the general formula (1), X is H or CH ₃ , m is a positive integer, and the Tg (glass transition temperature) of the polymer brush is −5 ° C. or lower.

FIG. 7 is a cross-sectional view showing an example of a polymer brush formed on a substrate as a weak anchoring alignment film.
As shown in FIG. 7, the liquid crystal molecules Lp permeate the surface layer portion of the polymer brush 2 formed on the substrate 13B, and the surface layer portion of the polymer brush 2 in contact with the liquid crystal molecules Lp is swollen (FIG. 7). The swollen state is not shown in the figure).

  In the present specification, the portion of the polymer brush 2 into which the liquid crystal molecules Lp have permeated is represented as the coexisting portion 4, and the portion of the polymer brush 2 into which the liquid crystal molecules Lp have not permeated is represented as the polymer brush layer 3. In FIG. 7, the coexistence part 4 and the polymer brush layer 3 are clearly distinguished from each other for easy understanding of the present invention, but actually, the boundary between the coexistence part 4 and the polymer brush layer 3 is shown. It is difficult to distinguish.

  By using the polymer brush 2 as described above, the Tg (glass transition temperature) of the coexistence part 4 is considerably lower than the normal temperature, so that the shape of the coexistence part 4 can be freely changed at normal temperature. . For this reason, the state of the coexistence part 4 changes at the interface between the coexistence part 4 and the liquid crystal molecules Lp, and the liquid crystal molecules Lp are forced to align in the horizontal direction with respect to the substrate 13B, while the alignment forcing force is in any direction within the plane It is possible to realize a state without zero (zero surface anchoring state).

  The Tg of the coexistence part 4 differs depending on the types of the polymer brush 2 and the liquid crystal molecules Lp to be used, and thus cannot be uniquely defined, but is generally lower than the Tg of the polymer brush 2 alone. The Tg of the coexistence part 4 also changes depending on the degree of penetration of the liquid crystal molecules Lp into the polymer brush 2 (that is, the ratio between the polymer brush 2 and the liquid crystal molecules Lp). Specifically, in the coexistence part 4, the coexistence part 4 on the liquid crystal molecule Lp side with a large proportion of the liquid crystal molecules Lp has a low Tg, and the coexistence part 4 on the polymer brush layer 3 side with a small proportion of the liquid crystal molecules Lp has a high Tg. Become.

However, the polymer brush 2 is represented by the above general formula (1). In the general formula (1), X is H or CH ₃ , m is a positive integer, and Tg of the polymer brush is −5 ° C. By using the following, the Tg of the coexistence part 4 can be set to a temperature sufficiently lower than room temperature, so that the liquid crystal molecules Lp are forced to align in a plane parallel to the surface of the substrate 13B at room temperature. However, it is possible to realize a state where there is no alignment forcing force in any direction in the plane (zero plane anchoring state).

  The surface of the substrate 13B may be flattened as necessary. The planarization process is not particularly limited, and can be performed using a method known in the technical field. An example of the planarization process is a method of forming a planarization film on the surface of the substrate 13B. For example, a UV curable transparent resin or the like may be applied to the surface of the substrate 13B and UV cured.

Examples of the substrate 13B include an array substrate and a counter substrate.
An example of the array substrate is an active matrix array substrate. In this active matrix array substrate, gate wiring and source wiring are generally arranged in a matrix form on a glass substrate, and an active element such as a thin layer transistor (TFT) is formed at the intersection. A pixel electrode is connected to the active element.

  An example of the counter substrate is a color filter substrate. In general, the color filter substrate is formed by forming a black matrix on a glass substrate to prevent unnecessary light leakage, and then adding R (red), G (green), and B (blue) colored layers. A pattern is formed, and a protective film is formed if necessary. When these substrates 13B are used, a transparent resin may be applied to the surface of the substrate 13B and cured to form a planarizing film.

The polymer brush 2 formed on the substrate 13B is represented by the general formula (1). In the general formula (1), X is H or CH ₃ and m is a positive integer. Those having a Tg of −5 ° C. or lower can be used. Here, the polymer brush 2 preferably has a structure in which a large number of graft polymer chains extend in a direction perpendicular to the surface of the substrate 13B at a high density.

  Generally, a graft polymer chain having one end fixed to the surface of the substrate 13B has a thread-string-like contracted structure when the graft density is low, but the polymer brush 2 has a high graft density, so that the adjacent graft polymer Due to the chain interaction (steric repulsion), the substrate 13B has a structure extending in the direction perpendicular to the surface.

In the present specification, “high density” means the density of graft polymer chains that are so dense that steric repulsion occurs between adjacent graft polymer chains, and is generally 0.1 / nm ² or more, preferably 0. The density is from 1 to 1.2 lines / nm ² . In the present specification, the “density of graft polymer chains” means the number of graft polymer chains formed on the surface of the substrate 13B per unit area (nm ² ).
The polymer brush 2 may have a number of graft polymer chains provided at a density lower than the “high density” shown above.

  The polymer brush 2 forms a layer of the polymer brush 2 on the surface of the substrate 13B. The layer thickness of the polymer brush 2 is not particularly limited, but is generally several tens of nm, specifically 1 nm or more and less than 100 nm, preferably 10 nm to 80 nm. Further, the layer of the polymer brush 2 has a size exclusion effect, and a substance having a certain size cannot pass through the layer of the polymer brush 2. Therefore, even if the thickness of the polymer brush 2 is reduced, it is possible to prevent impurities from entering the liquid crystal molecules Lp from the base.

  It does not specifically limit as a formation method of the polymer brush 2, It can carry out using a well-known method in the said technical field. Specifically, the polymer brush 2 can be formed by living radical polymerization of a radical polymerizable monomer. Here, in this specification, “living radical polymerization” means that the chain transfer reaction and termination reaction are not substantially caused in the radical polymerization reaction, and the chain growth terminal is active even after the radical polymerizable monomer is completely reacted. It means a polymerization reaction to be retained.

  In this polymerization reaction, the polymerization activity is retained at the end of the produced polymer even after the completion of the polymerization reaction, and when the radical polymerizable monomer is added, the polymerization reaction can be started again. Living radical polymerization allows the synthesis of a polymer having an arbitrary average molecular weight by adjusting the concentration ratio between the radical polymerizable monomer and the polymerization initiator, and the molecular weight distribution of the resulting polymer is extremely narrow. There are features.

  A typical example of living radical polymerization is atom transfer radical polymerization (ATRP). For example, atom transfer living radical polymerization of a radical polymerizable monomer is performed using a copper halide / ligand complex in the presence of a polymerization initiator. A radical polymerizable monomer is added to a growing radical that reversibly grows by pulling out the terminal halogen of the polymer by a copper halide / ligand complex, and the molecular weight distribution is achieved by reversible activation / deactivation with sufficient frequency. Is regulated.

  The radical polymerizable monomer used in the living radical polymerization has an unsaturated bond capable of performing radical polymerization in the presence of an organic radical, and examples thereof include t-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, Methacrylate monomers such as nonyl methacrylate, lauryl methacrylate, n-octyl methacrylate; acrylate monomers such as t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, benzyl acrylate, lauryl acrylate, n-octyl acrylate; styrene, Styrene derivatives (for example, o-, m-, p-methoxystyrene, o-, m-, pt-butoxystyrene, o-, m-, p-chloromethyl Ethylene), vinyl esters (eg, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl acetate, etc.), vinyl ketones (eg, vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone, etc.), N-vinyl compounds (For example, N-vinylpyrrolidone, N-vinylpyrrole, N-vinylcarbazole, N-vinylindole, etc.), (meth) acrylic acid derivatives (for example, acrylonitrile, methacrylonitrile, acrylamide, isopropylacrylamide, methacrylamide, etc.), halogen And vinyl monomers such as vinyl chlorides (for example, vinyl chloride, vinylidene chloride, tetrachloroethylene, hexachloroprene, vinyl fluoride, etc.). These various radically polymerizable monomers may be used alone or in combination of two or more.

  The polymerization initiator is not particularly limited, and those generally known in living radical polymerization can be used. Examples of the polymerization initiator include p-chloromethylstyrene, α-dichloroxylene, α, α-dichloroxylene, α, α-dibromoxylene, hexakis (α-bromomethyl) benzene, benzyl chloride, benzyl bromide, 1- Benzyl halides such as bromo-1-phenylethane, 1-chloro-1-phenylethane; propyl-2-bromopropionate, methyl-2-chloropropionate, ethyl-2-chloropropionate, methyl- Carboxylic acids in which the α-position is halogenated such as 2-bromopropionate and ethyl-2-bromoisobutyrate (EBIB); Tosyl halides such as p-toluenesulfonyl chloride (TsCl); Tetrachloromethane, Tribromo Alkanes such as methane, 1-vinylethyl chloride, 1-vinylethyl bromide Ruharogen products; halogenated derivatives of phosphoric acid esters such as dimethyl phosphoric acid chloride and the like. These various polymerization initiators may be used alone or in combination of two or more.

  The copper halide that gives the copper halide / ligand complex is not particularly limited, and those generally known in living radical polymerization can be used. Examples of the copper halide include CuBr, CuCl, and CuI. These various copper halides may be used alone or in combination of two or more.

  The ligand compound that gives the copper halide / ligand complex is not particularly limited, and those generally known in living radical polymerization can be used. Examples of ligand compounds include triphenylphosphane, 4,4′-dinonyl-2,2′-dipyridine (dNbipy), N, N, N ′, N′N ″ -pentamethyldiethylenetriamine, 1,1,4 , 7,10,10-hexamethyltriethylenetetraamine, etc. These various ligand compounds may be used alone or in combination of two or more.

  The amount of the radically polymerizable monomer, polymerization initiator, copper halide and ligand compound may be appropriately adjusted according to the type of raw material used. In general, the amount of the radically polymerizable monomer is 1 mol of the polymerization initiator. Is 5 to 10,000 mol, preferably 50 to 5,000 mol, copper halide is 0.1 to 100 mol, preferably 0.5 to 100 mol, and the ligand compound is 0.2 to 200 mol, preferably 1.0 to 200 mol. is there.

  Living radical polymerization is usually performed without a solvent, but a solvent generally used in living radical polymerization may be used. Examples of usable solvents include benzene, toluene, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetone, chloroform, carbon tetrachloride, tetrahydrofuran (THF), ethyl acetate, trifluoromethylbenzene, and the like. And organic solvents such as water, methanol, ethanol, isopropanol, n-butanol, ethyl cellosolve, butyl cellosolve, 1-methoxy-2-propanol and the like. These various solvents may be used alone or in combination of two or more. The amount of the solvent may be appropriately adjusted according to the type of raw material to be used. Generally, the solvent is 0.01 to 100 mL, preferably 0.05 to 10 mL with respect to 1 g of the radical polymerizable monomer. is there.

  Living radical polymerization can be performed by immersing the substrate 13B in a polymer brush forming solution containing the above raw materials, or applying a polymer brush forming solution containing the above raw materials to the substrate 13B and heating. The heating conditions are not particularly limited, and may be appropriately adjusted according to the raw materials used. In general, the heating temperature is 60 to 150 ° C., and the heating time is 0.1 to 10 hours. This polymerization reaction is generally carried out at normal pressure, but it may be pressurized or reduced. In addition, you may wash | clean the board | substrate 13B before formation of the polymer brush 2 as needed.

  The molecular weight of the polymer brush 2 formed by living radical polymerization can be adjusted depending on the reaction temperature, reaction time, and the type and amount of the raw material used, but generally the number average molecular weight is 500 to 1,000,000, preferably Can form a polymer brush 2 of 1,000 to 500,000. Further, the molecular weight distribution (Mw / Mn) of the polymer brush 2 can be controlled between 1.05 and 1.60.

  The polymer brush 2 may be formed on the surface of the substrate 13B through an immobilization film as necessary from the viewpoint of enhancing the adhesion between the substrate 13B and the polymer brush 2. The immobilization film is not particularly limited as long as it has excellent adhesion to the substrate 13B and the polymer brush 2, and a generally known film can be used for living radical polymerization. Examples of the immobilization film include a film formed from an alkoxysilane compound represented by the following general formula (2).

In the general formula (2), each R ¹ is independently a C1-C3 alkyl group, preferably a methyl group or an ethyl group, each R ² is independently a methyl group or an ethyl group, and X is a halogen atom. , Preferably Br, and n is an integer of 3 to 10, more preferably an integer of 4 to 8.

  The polymer brush 2 is preferably covalently bonded to the immobilization film. If the immobilization film and the polymer brush 2 are connected by a covalent bond having a strong binding force, the polymer brush 2 can be sufficiently prevented from peeling off. As a result, the possibility of deterioration of the characteristics of the liquid crystal panel 11 is reduced, and the reliability of the liquid crystal panel 11 is improved.

  The method for forming the immobilization film is not particularly limited, and may be appropriately set depending on the material to be used. For example, the immobilization film can be formed by immersing the substrate 13B in the immobilization film forming solution, or by applying the immobilization film formation solution to the substrate 13B and then drying. Here, in order to form an immobilization film in a predetermined portion, masking may be performed on a portion where the immobilization film is not formed. Further, the substrate 13B may be cleaned before the formation of the immobilization film, if necessary.

  The method for injecting the liquid crystal molecules Lp between the substrate 13A and the substrate 13B on which the polymer brush 2 is formed is not particularly limited, and a vacuum injection method using a capillary phenomenon or a liquid crystal dropping injection method (ODF: One Drop Filling). Etc.) can be used. For example, when using a vacuum injection method utilizing capillary action, the following may be performed.

  First, the electrode layer 15 is formed on one substrate 13A by a known method. On the other substrate 13B, a return electrode layer 19 and a spacer are formed by a known method such as photolithography by a known method, and then an immobilization film (if necessary) and a polymer brush 2 are formed. Here, if necessary, it may be flattened by forming a flattening film or the like on the substrate 13B (other than the spacer portion), and an immobilization film (if necessary) and the polymer brush 2 may be formed thereon. .

  Next, after cleaning and drying one substrate 13A, a sealing material is applied, superimposed on the other substrate 13B, and the sealing material is cured and bonded by heating or UV irradiation. Here, it is necessary to open an injection port for injecting the liquid crystal molecules Lp in a part of the sealing material. Next, after injecting liquid crystal molecules Lp between the substrates 13A and 13B by vacuum injection from the injection port, the injection port is sealed.

  The liquid crystal molecules Lp used in the present invention are not particularly limited, and those known in the technical field can be used. Among them, as the liquid crystal molecules Lp, those having an NI point (phase transition temperature from the N phase to the I phase) of the liquid crystal molecules Lp higher than the Tg of the coexisting portion 4 are preferable.

As described above, according to the liquid crystal panel 11, the backlight unit 12, the substrate 13 </ b> B on which the weak anchoring alignment film 17 is formed, and the weak anchoring alignment film 17 are arranged to face each other with a space therebetween. A liquid crystal that is disposed between the substrate 13A on which the strong anchoring alignment film 16 is formed, the weak anchoring alignment film 17 and the strong anchoring alignment film 16, and transmits or blocks light when the liquid crystal molecules Lp are driven. The layer 18, the driving electrode layer 15 provided on one of the substrate 13A and the substrate 13B and applying the electric field E to the liquid crystal molecules Lp, and the return applying the return electric field Er in the direction perpendicular to the electric field E to the liquid crystal molecules Lp. An electrode layer 19 is provided.
The drive electrode layer 15 displaces the alignment direction of the liquid crystal molecules Lp by the electric field E from the alignment direction of the liquid crystal molecules Lp when the electric field E is not applied, and the return electrode layer 19 generates the liquid crystal molecules by the return electric field Er. The alignment direction of the molecules Lp is displaced so as to return to the alignment direction of the liquid crystal molecules Lp when the electric field E is not applied.
In this way, the liquid crystal molecules Lp whose orientation direction is displaced by the electric field E generated by the drive electrode layer 15 are returned to the initial state by the return electric field Er generated by the return electrode 19, thereby driving the liquid crystal molecules Lp at high speed. Can be realized. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

Further, the weak anchoring alignment film 17 has a restraining force that restrains the alignment direction of the liquid crystal molecules Lp when the electric field E is applied, smaller than that of the strong anchoring alignment film 16.
Then, with the electric field E applied, the displacement angle in the alignment direction of the liquid crystal molecules Lp of the liquid crystal layer 18 gradually increases from the strong anchoring alignment film 16 side toward the weak anchoring alignment film 17 side.
Thereby, if a predetermined voltage sufficient to change the alignment direction of the liquid crystal molecules Lp on the weak anchoring alignment film 17 side is applied, the liquid crystal layer 18 of the liquid crystal panel 11 is driven and display can be performed. Therefore, the liquid crystal molecules Lp can be driven with a low voltage.
Moreover, according to the said structure, the liquid crystal molecule Lp is driven using the optical rotation of the liquid crystal molecule Lp. According to such a configuration, light changes along the alignment of the liquid crystal molecules Lp and transmits, so that a display with high transmittance can be performed.

[Second Embodiment]
Next, a second embodiment of the liquid crystal display element according to the present invention will be described. Note that in the second embodiment described below, the same reference numerals in the drawing denote the same components as those in the first embodiment, and a description thereof will be omitted. In the second embodiment, the arrangement of the electrode lines 20B in the drive electrode layer 15 is different from the first embodiment.
FIG. 8 is a diagram showing the relationship between the electrode lines and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the second embodiment, using a liquid crystal with positive dielectric anisotropy and no electric field applied. It is. FIG. 9 shows the relationship between the electrode line and the orientation direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the second embodiment using a liquid crystal with positive dielectric anisotropy and applying an electric field. It is a figure which shows the example of.

  As shown in FIG. 8, in the second embodiment, the drive electrode layer 15 is formed by arranging a plurality of electrode lines 20B in parallel along the surface of the substrate 13A. Here, each electrode line 20B is formed with its major axis direction inclined with respect to the direction Y along the substrate 13A, for example. The drive electrode layer 15 is formed by arranging such electrode lines 20B in parallel at regular intervals along a direction X orthogonal to the direction Y along the substrate 13A.

  In such a driving electrode layer 15, the positive liquid crystal molecules Lp are aligned in the alignment treatment direction (direction) in the strong anchoring alignment film 16 in a state where the electric field E is not applied between the electrode lines 20 B and 20 B adjacent to each other. Y).

  As shown in FIG. 9, even when an electric field E is applied to the positive type liquid crystal molecules Lp, the major axis direction is the alignment treatment direction (direction Y) of the strong anchoring alignment film 16 on the strong anchoring alignment film 16 side. ) To maintain the initial alignment state. On the other hand, on the weak anchoring alignment film 17 side, the liquid crystal molecules Lp are displaced in the plane parallel to the substrate 13B by the applied electric field E, and when the electric field strength reaches a certain value, its length is increased. The axial direction is along the direction parallel to the electric field E, that is, the direction orthogonal to the electrode wire 20B.

  Also in the liquid crystal panel 11 of this embodiment having such a drive electrode layer 15, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are generated by the return electric field Er generated by the return electrode 19. By returning to the initial state, the driving of the liquid crystal molecules Lp can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

[Third Embodiment]
Next, a third embodiment of the liquid crystal display element according to the present invention will be described. Note that in the third embodiment described below, the same reference numerals in the drawing denote the same components as those in the first and second embodiments, and a description thereof will be omitted. In the third embodiment, the arrangement of the electrode lines 20C in the drive electrode layer 15 is different from the first and second embodiments.
FIG. 10 is a diagram showing the relationship between the electrode line and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the third embodiment when a liquid crystal having positive dielectric anisotropy is used and no electric field is applied. It is. FIG. 11 shows a liquid crystal panel of the liquid crystal display shown as the third embodiment, in which a liquid crystal having a positive dielectric anisotropy is used, and the relationship between the electrode line and the orientation direction of the liquid crystal molecules when an electric field is applied. It is a figure which shows the example of.

  As shown in FIG. 10, in the third embodiment, the drive electrode layer 15 is formed by arranging a plurality of electrode lines 20C in parallel along the surface of the substrate 13A. Here, in each pixel, each electrode line 20C includes a first inclined portion 20a inclined by a predetermined angle α with respect to the direction Y along the substrate 13A, and a second inclination inclined by a predetermined angle −α with respect to the direction Y. The portion 20b has a “<” shape that is continuous in the direction Y, which is the major axis direction. The drive electrode layer 15 is formed by arranging such electrode lines 20C in parallel along a direction X perpendicular to the direction Y along the substrate 13A at regular intervals.

  In such a driving electrode layer 15, the positive liquid crystal molecules Lp are aligned in the alignment treatment direction (direction) in the strong anchoring alignment film 16 in a state where the electric field E is not applied between the electrode lines 20 </ b> C and 20 </ b> C adjacent to each other. Y).

As shown in FIG. 11, even when an electric field E is applied to the positive type liquid crystal molecules Lp, the major axis direction on the strong anchoring alignment film 16 side is the alignment treatment direction (direction Y) of the strong anchoring alignment film 16. ) To maintain the initial alignment state. On the other hand, on the weak anchoring alignment film 17 side, the liquid crystal molecules Lp are displaced in the plane parallel to the substrate 13B by the applied electric field E, and when the electric field strength reaches a certain value, its length is increased. It is oriented so that the axial direction is orthogonal to the first inclined portion 20a and the second inclined portion 20b. Specifically, when the electric field E is applied, the liquid crystal molecules Lp are orthogonal to the first inclined portions 20a between the first inclined portions 20a and 20a, and the liquid crystal molecules Lp are between the second inclined portions 20b and 20b. It is orthogonal to the second inclined portion 20b.
Here, in the drive electrode layer 15, the electrode line 20 </ b> C is bent in a “<” shape in each pixel. Therefore, when the electric field E is applied, the liquid crystal molecules Lp inclined by the angle α and the liquid crystal molecules Lp inclined by the angle −α with respect to the direction X are mixed to form an image. As a result, image deterioration when the liquid crystal panel 11 is viewed from an oblique direction inclined with respect to the panel surface can be suppressed.

  Also in the liquid crystal panel 11 of this embodiment having such a drive electrode layer 15, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are generated by the return electric field Er generated by the return electrode 19. By returning to the initial state, the driving of the liquid crystal molecules Lp can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

[Fourth Embodiment]
Next, a liquid crystal display device according to a fourth embodiment of the invention will be described. In addition, in 4th Embodiment demonstrated below, about the structure which is common in the said 1st-3rd embodiment, the same code | symbol is attached | subjected in a figure and the description is abbreviate | omitted. In the fourth embodiment, the drive electrode layer 15 similar to that in the first embodiment is provided, and the negative liquid crystal molecules Ln are driven.
FIG. 12 is a cross-sectional view showing a schematic configuration of the liquid crystal display shown as the fourth embodiment of the present invention. FIG. 13 is a diagram showing a distribution of alignment directions of liquid crystal molecules in a liquid crystal panel of the liquid crystal display shown as the fourth embodiment when a liquid crystal having a negative dielectric anisotropy is used and an electric field is applied. FIG. 14 shows the relationship between the electrode lines and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the fourth embodiment, using a liquid crystal having a negative dielectric anisotropy and applying no electric field. FIG. FIG. 15 shows the relationship between the electrode line and the orientation direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the fourth embodiment using a liquid crystal having negative dielectric anisotropy and applying an electric field. FIG. FIG. 16 shows a liquid crystal display element of the liquid crystal display shown as the fourth embodiment, in which liquid crystal having a negative dielectric anisotropy is used and the return electrode electrode line and the liquid crystal molecule orientation direction when no return electric field is applied. It is a figure which shows the relationship. FIG. 17 shows a liquid crystal display element of the liquid crystal display shown as the fourth embodiment, in which liquid crystal having negative dielectric anisotropy is used and the return electrode electrode line and the orientation direction of liquid crystal molecules in a state where a return electric field is applied. It is a figure which shows the relationship.

  As shown in FIGS. 12 and 13, in this embodiment, the polarizing plate 14A and the polarizing plate 14B are arranged in crossed Nicols, the transmission axis direction of the polarizing plate 14A is set along the direction X, and the other polarizing plate 14B. The transmission axis direction is set along the direction Y.

  The drive electrode layer 15 is formed by arranging a plurality of electrode lines 20A in parallel along the surface of the substrate 13A. As shown in FIGS. 14 and 15, each electrode line 20 </ b> A is linearly formed so that the major axis direction extends along the direction Y in a plane parallel to the surface of the substrate 13 </ b> A, for example. The drive electrode layer 15 has such electrode lines 20A arranged in parallel at regular intervals along a direction X orthogonal to the direction Y in a plane parallel to the surface of the substrate 13A.

The liquid crystal molecules Ln of the liquid crystal layer 18 are negative types having negative dielectric anisotropy, small dielectric properties in the major axis direction, and large in the direction perpendicular to the major axis direction.
As shown in FIGS. 12 and 14, when negative liquid crystal molecules Ln are used, the alignment treatment direction of the strong anchoring alignment film 16 for regulating the alignment direction of the liquid crystal molecules Ln without applying the electric field E is changed. A direction perpendicular to the major axis direction of each electrode line 20A (direction X in FIG. 12). Further, the polarizing plate 14A and the polarizing plate 14B are arranged in crossed Nicols, and a strong anchoring alignment film for restricting the alignment direction of the liquid crystal molecules Ln when the transmission axis direction of the polarizing plate 14A does not apply the electric field E. 16 is set so as to coincide with the direction of orientation processing with respect to 16 (direction X in FIG. 12). Then, in the state where the electric field E is not applied, the light from the backlight unit 12 side is not transmitted.

  As shown in FIG. 13, even when the electric field E is applied, the negative type liquid crystal molecules Ln have an alignment treatment of the strong anchoring alignment film 16 on the strong anchoring alignment film 16 side as described above. The initial alignment state (direction X) along the direction is maintained. On the other hand, as shown in FIG. 15, on the weak anchoring alignment film 17 side, due to the applied electric field E, the liquid crystal molecules Ln are displaced in the alignment angle in a plane parallel to the substrate 13B, and the electric field strength becomes a certain value. When it reaches, the major axis direction is along the direction perpendicular to the electric field E, that is, the direction Y parallel to the substrate 13B. In this way, in the state where the electric field E is applied, the displacement angle in the alignment direction of the liquid crystal molecules Ln of the liquid crystal layer 18 gradually increases from the strong anchoring alignment film 16 side toward the weak anchoring alignment film 17 side. When an electric field of a certain value or more is applied, the alignment direction (direction Y) of the liquid crystal molecules Ln on the weak anchoring alignment film 17 side becomes a direction orthogonal to the electric field E and coincides with the transmission axis direction of the polarizing plate 14B. The light passing through the polarizing plate 14A from the light unit 12 side changes its polarization plane along the distribution in the alignment direction of the liquid crystal molecules Ln, and is emitted through the polarizing plate 14B on the opposite side.

  As shown in FIG. 16, after the application of the electric field E is stopped after the electric field E is applied, when the return electric field Er is applied in the return electrode layer 19 as shown in FIG. 17, the liquid crystal molecules Ln are adjacent to each other. The orientation direction changes so that the major axis direction coincides with the direction X parallel to the electrode line 21 between the electrode lines 21 and 21 to be operated. Thereby, the alignment direction of the liquid crystal molecules Ln returns to the initial alignment state.

  Also in the liquid crystal panel 11 of this embodiment having such a drive electrode layer 15, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are generated by the return electric field Er generated by the return electrode 19. By returning to the initial state, the driving of the liquid crystal molecules Lp can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

Moreover, even if a short-circuit electric field Et is generated between the electrode line 20A of the drive electrode layer 15 and the electrode line 21 of the return electrode layer 19 by using the negative liquid crystal molecules Ln, the liquid crystal molecules Ln Therefore, the liquid crystal molecules Ln do not rise in the direction in which the major axis direction is orthogonal to the surfaces of the substrates 13A and 13B as in the first to third embodiments. Therefore, light from the backlight unit 12 side does not leak through the polarizing plate 14B.
In such a configuration, when the application of the electric field E in the drive electrode layer 15 and the application of the return electric field Er in the return electrode layer 19 are switched, the application of the return electric field Er is started before the application of the electric field E is finished. can do. Thereby, the switching timing from the state where the electric field E is applied to the application of the return electric field Er can be shortened. As a result, also in this respect, the display response in the liquid crystal panel 11 can be improved.

[Fifth Embodiment]
Next, a fifth embodiment of the liquid crystal display element according to the present invention will be described. In addition, in 5th Embodiment demonstrated below, about the structure which is common in the said 1st-4th embodiment, the same code | symbol is attached | subjected in a figure and the description is abbreviate | omitted. In the fifth embodiment, the same drive electrode layer 15 as that in the second embodiment is provided, and negative liquid crystal molecules Ln are driven.
FIG. 18 is a diagram showing the relationship between the electrode line and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the fifth embodiment when a liquid crystal having negative dielectric anisotropy is used and no electric field is applied. It is. FIG. 19 shows the relationship between the electrode line and the orientation direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the fifth embodiment when a liquid crystal having a negative dielectric anisotropy is applied and an electric field is applied. It is a figure which shows the example of.

  In this embodiment, the transmission axis direction of one polarizing plate 14A is set along the direction X as in the fourth embodiment, and the transmission axis direction of the other polarizing plate 14B is set along the direction Y. ing.

  As shown in FIG. 18, the drive electrode layer 15 is formed by arranging a plurality of electrode lines 20B in parallel along the surface of the substrate 13A. Each electrode line 20B is formed with its major axis direction inclined with respect to the direction Y along the substrate 13A, for example. The drive electrode layer 15 is formed by arranging such electrode lines 20B in parallel at regular intervals along a direction X orthogonal to the direction Y along the substrate 13A.

  In such an electrode layer 15, the negative liquid crystal molecules Ln are aligned in the alignment treatment direction (direction X in the strong anchoring alignment film 16) in a state where the electric field E is not applied between the adjacent electrode lines 20 B and 20 B. ). In the state where the electric field E is not applied, the liquid crystal molecules Ln of the liquid crystal layer 18 are aligned along the direction X, and light from the backlight unit 12 side is not transmitted.

  As shown in FIG. 19, when the electric field E is applied to the negative type liquid crystal molecules Ln, the major axis direction is in the alignment treatment direction (direction X) of the strong anchoring alignment film 16 on the strong anchoring alignment film 16 side. The initial alignment state along is maintained. On the other hand, on the weak anchoring alignment film 17 side, the liquid crystal molecules Ln are displaced in the plane parallel to the substrate 13B by the applied electric field E, and when the electric field strength reaches a certain value, its length is increased. The axial direction is along the direction orthogonal to the electric field E, that is, the direction parallel to the electrode wire 20B.

  Also in the liquid crystal panel 11 of this embodiment having such a drive electrode layer 15, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are generated by the return electric field Er generated by the return electrode 19. By returning to the initial state, the driving of the liquid crystal molecules Lp can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

  In addition, by using the negative liquid crystal molecules Ln, it is possible to shorten the switching timing from the state where the electric field E is applied to the application of the return electric field Er. As a result, also in this respect, the display response in the liquid crystal panel 11 can be improved.

[Sixth Embodiment]
Next, a liquid crystal display device according to a sixth embodiment of the invention will be described. In addition, in 6th Embodiment demonstrated below, about the structure which is common in the said 1st-5th embodiment, the same code | symbol is attached | subjected in a figure and the description is abbreviate | omitted. In the sixth embodiment, the same drive electrode layer 15 as that in the third embodiment is provided, and negative liquid crystal molecules Ln are driven.
FIG. 20 is a diagram showing the relationship between the electrode lines and the alignment direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the sixth embodiment using a liquid crystal having a negative dielectric anisotropy and no electric field applied. It is. FIG. 21 shows the relationship between the electrode line and the orientation direction of the liquid crystal molecules in the liquid crystal panel of the liquid crystal display shown as the sixth embodiment when a liquid crystal having a negative dielectric anisotropy is applied and an electric field is applied. It is a figure which shows the example of.

  In this embodiment, the transmission axis direction of one polarizing plate 14A is set along the direction X as in the fourth embodiment, and the transmission axis direction of the other polarizing plate 14B is set along the direction Y. ing.

  As shown in FIG. 20, the drive electrode layer 15 is formed by arranging a plurality of electrode lines 20C in parallel along the surface of the substrate 13A. Each electrode line 20C includes, in each pixel, a first inclined portion 20a inclined by a predetermined angle α with respect to the direction Y along the substrate 13A, and a second inclined portion 20b inclined by a predetermined angle −α with respect to the direction Y. However, it forms a continuous “<” shape in the direction Y which is the major axis direction. The drive electrode layer 15 is formed by arranging such electrode lines 20C in parallel along a direction X perpendicular to the direction Y along the substrate 13A at regular intervals.

  In such an electrode layer 15, the negative liquid crystal molecules Ln are aligned in the alignment treatment direction (direction X in the strong anchoring alignment film 16) without applying an electric field E between the electrode lines 20 </ b> C and 20 </ b> C adjacent to each other. ). In the state where the electric field E is not applied, the liquid crystal molecules Ln of the liquid crystal layer 18 are aligned along the direction X, and light from the backlight unit 12 side is not transmitted.

As shown in FIG. 21, when the electric field E is applied to the negative liquid crystal molecules Ln, the major axis direction is in the alignment treatment direction (direction X) of the strong anchoring alignment film 16 on the strong anchoring alignment film 16 side. The initial alignment state along is maintained. On the other hand, on the weak anchoring alignment film 17 side, the liquid crystal molecules Ln are displaced in the plane parallel to the substrate 13B by the applied electric field E, and when the electric field strength reaches a certain value, its length is increased. It is oriented so that the axial direction is parallel to the first inclined portion 20a and the second inclined portion 20b. Specifically, when the electric field E is applied, the liquid crystal molecules Ln are parallel to the first inclined portions 20a between the first inclined portions 20a and 20a, and the liquid crystal molecules Ln are between the second inclined portions 20b and 20b. It becomes parallel to the second inclined portion 20b.
Here, in the drive electrode layer 15, the electrode line 20 </ b> C is bent in a “<” shape in each pixel. Therefore, when the electric field E is applied, liquid crystal molecules Ln inclined at two different angles are mixed to form an image. As a result, image deterioration when the liquid crystal panel 11 is viewed from an oblique direction inclined with respect to the panel surface can be suppressed.

  Also in the liquid crystal panel 11 of this embodiment having such a drive electrode layer 15, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are generated by the return electric field Er generated by the return electrode 19. By returning to the initial state, the driving of the liquid crystal molecules Lp can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

  In addition, by using the negative liquid crystal molecules Ln, it is possible to shorten the switching timing from the state where the electric field E is applied to the application of the return electric field Er. As a result, also in this respect, the display response in the liquid crystal panel 11 can be improved.

The preferred embodiments of the present invention have been described in detail above, but various modifications and equivalent embodiments are possible from those having ordinary knowledge in the technical field.
Therefore, the scope of right of the present invention is not limited to this, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the claims are also included in the present invention.

  For example, in the above-described embodiment, specific methods for forming the strong anchoring alignment film 16 and the weak anchoring alignment film 17 are illustrated, but the present invention is not limited thereto. That is, if the strong anchoring alignment film 16 and the weak anchoring alignment film 17 have different alignment forcing forces to correct the alignment direction of the liquid crystal molecules Lp when the electric field E is applied, the strong anchoring alignment film 17 16, The weak anchoring alignment film 17 may be formed by any other method and material.

  In the above-described embodiment, the strong anchoring alignment film 16 is disposed on the backlight unit 12 side, and the weak anchoring alignment film 17 is disposed on the side away from the backlight unit 12, but the present invention is not limited thereto. The strong anchoring alignment film 16 may be disposed on the side away from the backlight unit 12, and the weak anchoring alignment film 17 may be disposed on the backlight unit 12 side.

The drive electrode layer 15 is not limited to the backlight unit 12 side but may be disposed on the opposite side.
Further, the return electrode layer 19 is not limited to the side away from the backlight unit 12 but may be disposed on the opposite side.

  In the first to sixth embodiments, the polarizing plate 14A and the polarizing plate 14B are arranged in crossed Nicols, and the transmission axis direction of the polarizing plate 14A is the alignment direction of the liquid crystal molecules L in the state where the electric field E is not applied. Although the example in the case where it coincides with the alignment treatment direction with respect to the strong anchoring alignment film 16 for restricting the alignment is shown, the transmission axis direction of the polarizing plate 14A is aligned with the alignment of the liquid crystal molecules L with no electric field E applied. You may make it orthogonal to the orientation process direction with respect to the strong anchoring orientation film 16 for regulating a direction.

  Furthermore, in the first to sixth embodiments, the liquid crystal molecules L have an alignment angle with respect to the initial alignment direction from the strong anchoring alignment film 16 side to the weak anchoring alignment film 17 side in the state where the electric field E is applied. The amount of displacement gradually increases, resulting in a spirally twisted orientation state. Here, in the liquid crystal molecules L, the displacement amount of the alignment angle of the liquid crystal molecules L is maximized in an intermediate portion between the strong anchoring alignment film 16 and the weak anchoring alignment film 17, and the weak anchoring alignment film 17 is larger than that portion. The displacement amount of the alignment angle of the liquid crystal molecules L may be uniform (maximum state). In other words, the liquid crystal molecules L are arranged in a spiral form in a region from the strong anchoring alignment film 16 side to an intermediate portion between the strong anchoring alignment film 16 and the weak anchoring alignment film 17 with the electric field E applied. In the region from the intermediate portion between the strong anchoring alignment film 16 and the weak anchoring alignment film 17 to the weak anchoring alignment film 17 side, they may be arranged uniformly.

  Furthermore, in the above embodiment, the strong anchoring alignment film 16 is provided on one side of the liquid crystal layer 18 and the weak anchoring alignment film 17 is provided on the other side, but this is not restrictive. The liquid crystal panel 11 may be configured to include the weak anchoring alignment films 17 on both sides of the liquid crystal layer 18. Even in such a configuration, the liquid crystal molecules Lp whose alignment direction is displaced by the electric field E generated by the drive electrode layer 15 are returned to the initial state by the return electric field Er generated by the return electrode 19, thereby driving the liquid crystal molecules Lp. Can be speeded up. Thereby, the display responsiveness in the liquid crystal panel 11 can be improved.

  Furthermore, in the above-described embodiment, the so-called normally black type liquid crystal panel 11 in which the display is dark when no voltage is applied and bright when the voltage is applied is described, but the present invention is not limited thereto. The liquid crystal panel 11 may have a so-called normally white configuration in which the display is bright when no voltage is applied and dark when the voltage is applied.

2 Polymer brush 3 Polymer brush layer 4 Coexistence part 7 Geometrical uneven structure 10 Liquid crystal display 11 Liquid crystal panel (liquid crystal display element)
11f Front surface 11r Back surface 12 Backlight unit 13A Substrate (second substrate)
13B substrate (first substrate)
14A, 14B Polarizing plate 15 Drive electrode layer 16 Strong anchoring alignment film (second alignment film)
17 Weak anchoring alignment film (first alignment film)
18 Liquid crystal layer 19 Return electrode layer 20 Electrode line 20a First inclined part 20b Second inclined part 21 Electrode line E Electric field Er Return electric field L Liquid crystal molecule

Claims (13)

A light source that emits light;
A first substrate on which a first alignment film is formed;
A second substrate on which a second alignment film disposed opposite to the first alignment film with a gap is formed;
A liquid crystal layer disposed between the first alignment film and the second alignment film and transmitting or blocking the light by driving liquid crystal molecules;
A driving electrode layer provided on one of the first substrate and the second substrate and applying an electric field in a direction along the first substrate and the second substrate to the liquid crystal molecules;
A return electric field provided on one of the first substrate and the second substrate, and in the liquid crystal molecules in a direction crossing the electric field in a direction along the first substrate and the second substrate. A return electrode layer for applying,
The liquid crystal layer is
In the state where the electric field is applied, the second alignment film side maintains the liquid crystal molecules aligned in the preset initial alignment direction, and the first alignment film side maintains the liquid crystal molecules. The alignment direction is changed from the initial alignment direction to the direction corresponding to the electric field in a plane parallel to the surface of the second substrate, whereby the first alignment film side is changed from the second alignment film side. toward the liquid crystal molecules are arranged in a spiral shape,
The first alignment film has a restraining force that restricts the alignment direction of the liquid crystal molecules when the electric field is applied is smaller than that of the second alignment film.
Wherein as the first alignment film, that has a polymer brush formed on the first substrate, a liquid crystal display device. The driving electrode layer displaces the alignment direction of the liquid crystal molecules by the electric field from the alignment direction of the liquid crystal molecules in a state where the electric field is not applied.
The liquid crystal display element according to claim 1, wherein the return electrode layer is displaced by the return electric field so that the alignment direction of the liquid crystal molecules returns to the alignment direction of the liquid crystal molecules in a state where the electric field is not applied.   The liquid crystal display element according to claim 1, wherein a plurality of electrode lines constituting the return electrode layer are formed to extend in a crossing direction with respect to the plurality of electrode lines constituting the drive electrode layer. While applying the electric field, towards the first alignment layer side from the second alignment film side, angular displacement of the orientation direction of the liquid crystal molecules of the liquid crystal layer is gradually increased, according to claim 1 Liquid crystal display element. Alignment direction of the liquid crystal molecules by the electric field generated by applying a predetermined voltage between the liquid crystal molecules located on the first alignment film side and the liquid crystal molecules located on the second alignment film side The liquid crystal display element according to claim 4 , wherein a difference in displacement angle is 0 ° or more and 90 ° or less. The drive electrode layer is composed of a plurality of electrode lines arranged on the first substrate or the second substrate surface,
During non-application of the electric field, the orientation direction of the liquid crystal molecules are parallel or perpendicular to the direction in which the electrode wire is continuous, the liquid crystal display device according to any one of claims 1 to 5. The drive electrode layer is composed of a plurality of electrode lines arranged on the first substrate or the second substrate surface ,
During non-application of the electric field, the orientation direction of the liquid crystal molecules are inclined with respect to the direction in which the electrode wire is continuous, the liquid crystal display device according to any one of claims 1 to 5. The liquid crystal display device according to any one of 7 claims 1 having a negative dielectric anisotropy of the liquid crystal molecules. And application of the electric field at the drive electrode layer, when switching between application of the return electric field in the return electrode layer, initiates the application of the return field prior to terminating the application of the electric field, according to claim 8 Liquid crystal display element. The dielectric anisotropy of the liquid crystal molecules is positive, the liquid crystal display device according to any one of claims 1 to 7. The liquid crystal display element according to claim 10 , wherein when the application of the electric field in the drive electrode layer and the application of the return electric field in the return electrode layer are switched, a time lag is kept constant. The drive electrode layer is provided on one of the first substrate and the second substrate, and the return electrode layer is provided on the other of the first substrate and the second substrate. The liquid crystal display element according to any one of 11. The liquid crystal display element according to claim 12, wherein the drive electrode layer is provided on the second substrate, and the return electrode layer is provided on the first substrate.

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