JP2013029775A - Vertical orientation type liquid crystal display device and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical orientation type liquid crystal display device in which display abnormality in a design terminal part is eliminated or reduced, and a production method thereof.SOLUTION: A vertical orientation type liquid crystal display device comprises a first substrate 31a, a first electrode 31b, a second substrate 32a, a second electrode 32b and a liquid crystal layer. Liquid crystal molecules in the liquid crystal layer fall down in response to applying voltages to both the electrodes, thereby displaying design composed of an area where both the electrodes are overlapped approximately in a view from a normal direction of a counter surface. A terminal part of the design includes a first end portion where an absolute value of an angle to a liquid crystal director direction is equal to or less than a predetermined value, and a second end portion which is positioned at a liquid crystal director direction side and in which an absolute value of an angle to the liquid crystal director direction is greater than the predetermined value, and an edge of the second electrode 32b in the second end portion extends for a predetermined length or longer than an edge of the first electrode 31b in the liquid crystal director direction.

Description

  The present invention relates to a vertical alignment type liquid crystal display device and a production method thereof.

  As a liquid crystal display device, a vertical alignment type liquid crystal display device (hereinafter also referred to as VA-LCD (Vertical Alignment-Liquid Crystal Display)) is known. In the VA-LCD, the liquid crystal molecules in the liquid crystal layer disposed between the upper and lower substrates are aligned substantially perpendicular to the main surface (opposing surface) of each substrate, and voltage is applied to the electrodes provided on each of the upper and lower substrates. Is applied, a voltage is applied to the liquid crystal layer, and the liquid crystal molecules are tilted in a substantially horizontal direction with respect to the main surface of the substrate, thereby enabling a predetermined design display.

  As a VA-LCD, there is known a mono-domain alignment type in which liquid crystal molecules in a liquid crystal layer are aligned in one direction when no voltage is applied. For example, a segment display type mono-domain VA-LCD is known. Then, there is a problem that a linear display abnormality (dark region) is visually recognized at the end portion of the design, and the display quality is impaired (see FIGS. 9A and 9B). When a voltage is applied, the liquid crystal molecules are tilted substantially perpendicular to the lines of electric force, but depending on the direction of the oblique electric field generated between the upper and lower electrodes, the liquid crystal molecules may be different from the liquid crystal director direction (liquid crystal central molecule alignment direction). Will cause an alignment defect (see FIG. 8). A display abnormality is visually recognized by such an alignment defect.

  As a technique for suppressing this type of alignment defect, for example, in a dot matrix display type VA-LCD, a technique in which upper and lower electrodes are partially overlapped and translated as in Patent Document 1, or a technique in Patent Document 2 is used. A technique for forming a cut in an electrode has been proposed.

JP 2003-241196 A Japanese Patent No. 3324926

  However, in the segment display type mono-domain VA-LCD, the design shape is not constant, and the electrode formation pattern is more complicated than that of the dot matrix display type. I could not.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vertical alignment type liquid crystal display device that eliminates or reduces display abnormality at the end of a design and a method for producing the same.

In order to achieve the above object, a vertical alignment type liquid crystal display device according to the first aspect of the present invention comprises:
A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. An alignment type liquid crystal display device,
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end portion of the design is located on the liquid crystal director direction side with the first end portion having an absolute value of an angle with respect to the liquid crystal director direction being equal to or less than a predetermined value, and the absolute value of the angle with respect to the liquid crystal director direction is A second end greater than a predetermined value,
The edge of the second electrode at the second end is extended by a predetermined length or more in the liquid crystal director direction than the edge of the first electrode.
It is characterized by that.

In order to achieve the above object, a vertical alignment type liquid crystal display device according to the second aspect of the present invention provides
A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. An alignment type liquid crystal display device,
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end of the design is located on the side opposite to the first end where the absolute value of the angle relative to the liquid crystal director direction is equal to or less than a predetermined value, and the angle relative to the liquid crystal director direction. A second end having an absolute value greater than the predetermined value;
The edge of the first electrode at the second end is extended more than a predetermined length in the opposite direction than the edge of the second electrode.
It is characterized by that.

In order to achieve the above object, a method for producing a vertical alignment type liquid crystal display device according to the third aspect of the present invention comprises:
A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. A method for producing an alignment type liquid crystal display device,
Determining a layout of the first electrode and a layout of the second electrode;
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end portion of the design is located on the liquid crystal director direction side with the first end portion having an absolute value of an angle with respect to the liquid crystal director direction being equal to or less than a predetermined value, and the absolute value of the angle with respect to the liquid crystal director direction is A second end greater than a predetermined value,
The determining step satisfies a condition that an edge of the second electrode at the second end is extended by a predetermined length or more in the liquid crystal director direction than an edge of the first electrode. Determining the layout of the first electrode and the layout of the second electrode;
It is characterized by that.

In order to achieve the above object, a method for producing a vertical alignment type liquid crystal display device according to the fourth aspect of the present invention comprises:
A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. A method for producing an alignment type liquid crystal display device,
Determining a layout of the first electrode and a layout of the second electrode;
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end of the design is located on the side opposite to the first end where the absolute value of the angle relative to the liquid crystal director direction is equal to or less than a predetermined value, and the angle relative to the liquid crystal director direction. A second end having an absolute value greater than the predetermined value;
The determination step satisfies the condition that an edge of the first electrode at the second end is extended by a predetermined length or more in the opposite direction from an edge of the second electrode. Determining the layout of the first electrode and the layout of the second electrode;
It is characterized by that.

  According to the present invention, it is possible to eliminate or reduce display abnormality at the end of the design.

It is a schematic sectional drawing of the liquid crystal display device which concerns on one Embodiment of this invention. (A) is a figure explaining the relationship between the liquid-crystal director direction in a planar view, an up-and-down rubbing direction, and the transmission axis of a polarizing filter. (B) is a figure for demonstrating a liquid crystal director direction. (C) is a figure for demonstrating the pretilt angle of the liquid crystal molecule with respect to a 2nd board | substrate. It is a figure which shows the table | surface of the relationship between the angle to the design edge part with respect to a liquid crystal director direction, and display abnormality. (A) is a schematic plan view when the liquid crystal display device of FIG. 1 is viewed from above, and is a diagram for explaining the arrangement relationship between the first electrode and the second electrode. (B) is the AA line schematic sectional drawing shown to (a) of a liquid crystal display device. It is a figure which shows the table | surface of the relationship between the connection width of a connection part, and display abnormality. It is a figure which shows the table | surface of the relationship between the angle of a pretilt angle, and display abnormality. (A)-(c) is a figure for demonstrating the effect of the liquid crystal display device which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the conventional liquid crystal display device. (A) And (b) is a figure for demonstrating the display abnormality visually recognized in the conventional liquid crystal display device. (C) is a figure for demonstrating the display nonuniformity visually recognized in the conventional liquid crystal display device.

An embodiment according to the present invention will be described with reference to the drawings.
In the following description, it is assumed that the display surface direction of the liquid crystal display device (the direction of the viewer of the liquid crystal display device) of the predetermined component is “up” and the direction opposite to the display surface direction is “down”.

(Configuration of liquid crystal display device)
A liquid crystal display device 100 according to the present embodiment shown in FIG. 1 is a vertical alignment type liquid crystal display device, and includes a first polarizing filter 10, a second polarizing filter 20, a liquid crystal element 30, a transflective layer 40, A backlight 50.

  The first polarizing filter 10 and the second polarizing filter 20 are arranged to face each other, and the liquid crystal element 30 is provided between them.

  The 1st polarizing filter 10 is located on the liquid crystal element 30, and is comprised by the polarizing plate, for example. The first polarizing filter 10 has an absorption axis and a transmission axis orthogonal to the absorption axis, and emits light incident from the front surface side or the back surface side as linearly polarized light along the transmission axis.

  The second polarizing filter 20 is located below the liquid crystal element 30 and is configured by, for example, a polarizing plate. The second polarizing filter 20 has an absorption axis and a transmission axis perpendicular to the absorption axis, and emits light incident from the front side or the back side as linearly polarized light along the transmission axis.

  As shown in FIG. 2A, the first polarizing filter 10 and the second polarizing filter 20 have their transmission axes (or absorption axes) at an angle of + 45 ° and −45 ° with respect to the liquid crystal director direction. Is arranged in crossed Nicols. The liquid crystal display device 100 in such an arrangement is a normally black mode. The liquid crystal director direction will be described in detail later.

  The liquid crystal element 30 includes a first substrate unit 31, a second substrate unit 32, and a liquid crystal layer 33 including liquid crystal molecules 33a. The first substrate unit 31 and the second substrate unit 32 are arranged to face each other, and a liquid crystal layer 33 is provided between them. In FIG. 1 and the like, the liquid crystal molecules 33a are schematically represented by ellipsoids for convenience of explanation.

The first substrate unit 31 is disposed on the liquid crystal layer 33 and includes a first substrate 31a, a first electrode 31b, and a first alignment film 31c.
The second substrate unit 32 is disposed under the liquid crystal layer 33, and includes a second substrate 32a, a second electrode 32b, and a second alignment film 32c.

  The first substrate 31a and the second substrate 32a are transparent substrates such as a glass substrate and a plastic substrate, respectively, and transmit light.

Each of the first electrode 31b and the second electrode 32b is a transparent electrode that transmits light, and is formed from, for example, ITO (indium tin oxide) by a known method (for example, sputtering, vapor deposition, or etching). . The first electrode 31b is formed on the main surface (the surface on the liquid crystal layer 33 side) of the first substrate 31a in a shape corresponding to an arbitrary display pattern (for example, a shape capable of segmentally displaying figures, numbers, etc.). Similarly, the second electrode 32b is formed in a shape corresponding to an arbitrary display pattern on the main surface (surface on the liquid crystal layer 33 side) of the second substrate 32a.
The first electrode 31b and the second electrode 32b are disposed so as to face each other, and the liquid crystal display device 100 has both electrodes substantially in plan view (viewed from vertically above the facing surfaces of the first substrate 31a and the second substrate 32a). The design is displayed in the overlapping area. A voltage is applied to both the first electrode 31b and the second electrode 32b by passive driving. The shape and arrangement of the first electrode 31b and the second electrode 32b according to this embodiment will be described in detail later.

  The first alignment film 31c and the second alignment film 32c are films in contact with the liquid crystal layer 33, and are formed from, for example, polyimide by a known method (for example, flexographic printing). The first alignment film 31c is formed on the main surface (surface on the liquid crystal layer 33 side) of the first substrate 31a so as to cover the first electrode 31b. Similarly, the second alignment film 32c is formed on the main surface (surface on the liquid crystal layer 33 side) of the second substrate 32a so as to cover the second electrode 32b.

  In the first alignment film 31c and the second alignment film 32c, the alignment state (major axis direction of the liquid crystal molecules 33a) of the liquid crystal layer 33 when no voltage is applied to the liquid crystal molecules 33a is the main surface (opposing surface) of the substrate. It is a vertical alignment film that is defined substantially vertically, and aligns the liquid crystal molecules 33a substantially in one direction (so-called monodomain alignment). For this reason, the pretilt angle (angle formed by the major axis of the liquid crystal molecules 33a with respect to the main surface of the substrate) of the liquid crystal molecules 33a when no voltage is applied is approximately 90 °. Here, the pretilt means that the liquid crystal molecules 33a are tilted to some extent from the vertical direction in order to define the direction in which the liquid crystal molecules 33a are tilted when a voltage is applied (a liquid crystal director direction described later). The pretilt angle refers to an acute angle or an angle of 90 ° among the angles formed by the substrate (the main surface of the substrate) and the major axis of the liquid crystal molecules 33a. As the substrate normal direction is 90 °, the pretilt angle decreases from 90 ° as the pretilt is applied.

  The first alignment film 31c is rubbed in a first direction (for example, “upper rubbing direction” indicated by an arrow in FIG. 1 and the like) to form fine grooves. On the other hand, the second alignment film 32c is subjected to a rubbing process in a second direction that is opposite to the first direction (for example, a “down rubbing direction” indicated by an arrow in FIG. Is formed. For example, when viewed from the observer viewing the display surface of the liquid crystal display device 100 from above (viewing the display design in front), when the upper rubbing direction is 12 o'clock, the lower rubbing direction is 6 o'clock (see FIG. 2 (a)). In this embodiment, the rubbing process is performed in such a manner that the upper and lower substrates are antiparallel. Note that the alignment direction of the liquid crystal molecules 33a may be defined by a known process such as a photo-alignment process or a protrusion alignment process. In addition, an insulating film may be provided between the first electrode 31b and the first alignment film 31c and between the second electrode 32b and the second alignment film 32c, respectively, as necessary.

  As described above, the alignment direction of the liquid crystal molecules 33a is defined by the first alignment film 31c and the second alignment film 32c. When a voltage is applied to both the first electrode 31b and the second electrode 32b, the liquid crystal molecules 33a in the region where both electrodes substantially overlap in a plan view are perpendicular to the main surface of the substrate (see FIG. 2B). That is, the liquid crystal molecules 33a are tilted in the direction of the major axis (director) n of the liquid crystal molecules 33a schematically shown from the normal direction of the substrate. Here, the direction in which the pretilt angle (see FIG. 2C) of the liquid crystal molecules 33a with respect to the second substrate 32a (the main surface of the second substrate 32a) decreases when viewed from the normal direction of the substrate is referred to as “liquid crystal director direction”. (Refer to FIGS. 2A and 2B). The direction of the liquid crystal director indicates the direction of the director n of the liquid crystal molecules 33a at the center of the cross section of the liquid crystal layer 33 when viewed from the normal direction of the substrate (that is, the direction in which the liquid crystal molecules 33a (long axis) are inclined) (FIG. 2). (See (b)). In this embodiment, as shown in FIGS. 1 and 2A, the liquid crystal director direction is the same as the above-described lower rubbing direction.

  The liquid crystal layer 33 is sandwiched between the first substrate unit 31 and the second substrate unit 32. The first substrate unit 31 and the second substrate unit 32 are overlapped and fixed so as to face each other with a predetermined distance between them with a seal member (not shown) interposed therebetween. The liquid crystal material is confined in the sealed space formed by the first substrate unit 31, the second substrate unit 32, and the sealing member, and the liquid crystal layer 33 is formed. A liquid crystal material having a negative dielectric anisotropy Δε (Δε <0) is used. The liquid crystal layer 33 is given a predetermined pretilt angle by the first alignment film 31c and the second alignment film 32c. The pretilt angle of the liquid crystal layer 33 is set to “85 ° or more and 89.7 ° or less”, and more preferably “89 ° or more and 89.7 ° or less”. How the pretilt angle is defined will be described later in detail.

  The semi-transmissive reflective layer 40 is located below the second polarizing filter 20, reflects light from above, and transmits light from below, and is configured by, for example, a half mirror formed of aluminum or the like Is done. For example, the transflective layer 40 is directly formed on the lower surface of the polarizing plate constituting the second polarizing filter 20.

  The backlight 50 is located under the transflective layer 40 and emits light in a planar shape to illuminate the liquid crystal element 30 and the like. The backlight 50 is comprised by the combination of a light emitting diode and a light guide member, for example. The backlight 50 is appropriately used when the liquid crystal display device 100 performs bright display.

When no voltage is applied, since the liquid crystal molecules 33a are vertically aligned, the polarization direction (electric field oscillation direction) of the light that has passed through the second polarizing filter 20 from the lower side is hardly changed depending on the liquid crystal layer 33, and the second polarizing filter 20 And the first polarizing filter 10 arranged in a crossed Nicol relationship cannot be passed. Thus, the liquid crystal display device 100 is in a normally black mode.
On the other hand, when a voltage is applied to the first electrode 31b and the second electrode 32b that are a pair of electrodes, the liquid crystal layer 33 has a liquid crystal in a region where the voltage is applied (that is, a region where the pair of electrodes substantially overlap in plan view). The molecules 33a are inclined in the direction of the liquid crystal director, and in particular, the major axis of the liquid crystal molecules 33a located in the middle of the cross section of the liquid crystal layer 33 is substantially horizontal with the main surface of the substrate (first substrate 31a, second substrate 32a). Thereby, birefringence occurs in the light passing through the liquid crystal layer 33, the polarization direction of the light passing through the liquid crystal layer 33 is changed, and the light passing through the liquid crystal layer 33 from the lower side of the second polarizing filter 20 is the first. Passes through the polarizing filter 10. In this way, the liquid crystal display device 100 displays a predetermined design by a region through which light passes when a voltage is applied.

(About electrode formation and arrangement)
The inventor of the present application can visually recognize the first electrode 31b and the second electrode 32b at the design end by forming and arranging the first electrode 31b and the second electrode 32b so as to satisfy predetermined conditions in the liquid crystal display device 100 having the above-described configuration. It has been found that the occurrence of display abnormality can be suppressed.
Below, the formation aspect and arrangement | positioning relationship of an electrode peculiar to this embodiment are demonstrated.

  Here, in order to explain the display abnormality, a conventional liquid crystal display device 200 is shown in FIG. The liquid crystal display device 200 has the same general configuration as the liquid crystal display device 100 according to the present embodiment. Therefore, hereinafter, each configuration will be described using the same reference numerals as those of the liquid crystal display device 100. The conventional liquid crystal display device 200 is different from the liquid crystal display device 100 according to the present embodiment in “formation / arrangement relationship between the first electrode 31b and the second electrode 32b” and “pretilt angle of the liquid crystal layer 33”. In FIG. 8, the polarizing filter, the transflective layer, and the backlight are omitted.

  When a voltage is applied to the pair of electrodes of the first electrode 31b and the second electrode 32b, the liquid crystal molecules 33a are tilted so that the major axis is substantially perpendicular to the lines of electric force. However, in the conventional liquid crystal display device 200, depending on the generation direction of the oblique electric field, the liquid crystal molecules 33a that fall in a direction different from the liquid crystal director direction and become substantially perpendicular to the substrate surface are generated (see “FIG. 8“ Alignment defect region ”). Thus, in the region where the substantially vertical liquid crystal molecules 33a are generated (alignment defect region), birefringence does not occur sufficiently in the light passing through the liquid crystal layer 33 from the lower side of the second polarizing filter 20, so A linear display abnormality (dark region) is visually recognized without sufficiently passing through the one polarizing filter 10 (see FIGS. 9A and 9B).

The inventor of the present application has one end satisfying a predetermined condition in which an angle between a liquid crystal director direction and an end portion of the design (for example, a tangent to the end portion in a plan view) among the end portions of the design displayed by the liquid crystal display device. In this section, the second electrode 32b is provided extending from the edge toward the liquid crystal director direction, or the first electrode 31b is provided extending from the edge toward the direction opposite to the liquid crystal director direction. It was found that an oblique electric field generated during the period can be prevented from adversely affecting the liquid crystal molecules 33a and display anomalies can be eliminated or reduced.
Here, the “design” means a shape of 1 displayed in a region where both the first electrode 31b and the second electrode 32b substantially overlap when a voltage is applied. Since the design has one shape, the design is surrounded by a boundary line (straight line or curve) between the design display area and the non-display area. In the following description, an angle formed by the liquid crystal director direction and the end portion of the design (design outline) is referred to as an “end portion angle”.

  The inventor of the present application extends the first electrode 31b and the second electrode 32b from the design end portions (from each end edge) when the end portion angles are various angles (± 30 °, ± 40 °, 90 °). An extended liquid crystal display device was created. FIG. 3 shows the experimental results regarding the presence or absence of display abnormality in the prepared liquid crystal display device. This experimental result is a result when the frame frequency is 100 Hz.

In the table shown in FIG. 3, “extending in the forward direction” in the column of the extending direction means that the second electrode 32b is provided if one end having a certain end angle is an end located on the liquid crystal director direction side of the design. Is extended in the liquid crystal director direction side from one end thereof (the edge of the second electrode 32b is extended in the liquid crystal director direction), and one end portion having a certain end angle is located on the opposite side to the liquid crystal director direction of the design. In this case, the first electrode 31b is extended in the reverse direction from one end thereof (the edge of the first electrode 31b is extended in the reverse direction). Hereinafter, the extension of the electrode in this case is referred to as a forward extension.
On the other hand, “extending in the reverse direction” in the column of the extending direction means that if one end having a certain end angle is an end located on the liquid crystal director direction side of the design, the first electrode 31b is moved from the one end. If the one end portion extending in the liquid crystal director direction side and having one end angle is located on the opposite side of the design liquid crystal director direction, the second electrode 32b is moved from the one end portion to the opposite direction side. The case where it extended is shown. Hereinafter, the extension of the electrode in this case is referred to as reverse extension.
Note that the end located on the liquid crystal director direction side of the end of the design is connected to the midpoint of the parallel lines, for example, when a predetermined number of lines parallel to the liquid crystal director direction are prepared in the design area. It is an end located on the liquid crystal director side with respect to the ellipse line, or an end located on the liquid crystal director side with respect to a line perpendicular to the liquid crystal director direction passing through the center of gravity of the design area.

As shown in the drawing, in the forward extension from the design end with the end angle of 90 °, a very good result that no display abnormality is visually recognized is obtained. Further, in the case of the forward extension from the design end portion having an end portion angle of ± 40 °, although a display abnormality is visually recognized to some extent, a favorable result is obtained. However, in the case of the forward extension from the end of the design having an end angle of ± 30 °, the display abnormality was clearly recognized.
On the other hand, in the extension in the reverse direction, display abnormality was visually recognized at any end angle (± 30 °, ± 40 °, 90 °).

  As described above, the inventor of the present application satisfies one of the end portions of the design satisfying the condition that the angle of the end portion is “smaller than −30 ° or larger than +30” (hereinafter referred to as “end portion angle condition”). If the liquid crystal display device is designed (particularly the shape of the first electrode 31b and the shape of the second electrode 32b) and is produced so that both electrodes are in the above-described forward extension relationship, It has been found that display abnormality that can be visually recognized can be eliminated or reduced.

Here, a specific example of the liquid crystal display device 100 produced so as to satisfy the end corner condition will be described with reference to FIGS.
FIG. 4A is a schematic plan view of the liquid crystal display device 100 as viewed from above, in which the first electrode 31b is represented by a solid line and the second electrode 32b positioned below the first electrode 31b is represented by a dotted line. . FIG. 4B is a schematic cross-sectional view taken along line AA of the liquid crystal display device 100 shown in FIG. 4A, except for the first substrate 31a, the first electrode 31b, the second substrate 32a, and the second electrode 32b. It is the figure which abbreviate | omitted the structure. 4A and 4B show part of the electrode patterns of the first electrode 31b and the second electrode 32b.

  In the liquid crystal display device 100, the design is formed in a region where the first electrode 31b and the second electrode 32b substantially overlap when viewed from the direction perpendicular to the main surface of the substrate. Specifically, as shown in FIG. 4A, a regular pentagonal first design 60a and an arrow-shaped second design 60b are formed. In FIG. 4A, dots are added to the design area.

The first electrode 31b includes a first portion 311b including a portion overlapping the first design 60a, and a second portion 312b including a portion overlapping the second design 60b.
Is provided.

  In the present embodiment, the second electrode 32b has an electrode pattern formed in a shape substantially equal to the shape of the design as shown, and includes a first portion 321b including a portion overlapping the first design 60a, The second part 322b including the part overlapping the design 60b, the first part 321b, and the second part 322b are connected, and the role of the routing electrode between the designs (between the first design 60a and the second design 60b) A connection portion 323b having The connection width of the connection portion 323b is formed with a width of 100 μm or less. The connection width will be described in detail later.

Here, in the pentagon indicated by the first design 60a, the side located at the upper left end on the paper surface is referred to as the first end 61 of the first design 60a. Then, each of the other four sides is referred to as a second end 62, a third end 63, a fourth end 64, and a fifth end 65 in order counterclockwise from the first end 61.
Further, in the upward arrow on the paper surface indicated by the second design 60b, the triangular left oblique side indicating the arrow direction is called the sixth end portion 66, and the long left side of the rectangle located on the upper and lower sides of the triangular paper surface is the first side. The long end on the right side of the rectangle is called the eighth end 68.

  Further, as shown in the drawing, angles (end angles) formed by the liquid crystal director direction indicated by the two-dot chain line arrows and the first end portion 61 to the eighth end portion 68 are respectively θ1, θ2, θ3, θ4, Let θ5, θ6, θ7, and θ8. When the counterclockwise direction on the paper surface with respect to the liquid crystal director direction is the “+” direction, the angles θ1 to θ8 are, for example, θ1 is + 54 °, θ2 is −54 °, and θ3 is +18. It is assumed that θ, θ4 is + 90 °, θ5 is −18 °, θ6 is less than + 30 °, θ7 is + 90 °, and θ8 is + 90 °.

  In the present embodiment, at one end portion that satisfies the condition (end portion angle condition) that the angle of the end portion angle is “smaller than −30 ° or greater than +30”, the end portion is located on the liquid crystal director direction side of the design. The second electrode 32b extends from one end of the second electrode 32b toward the liquid crystal director direction (the edge of the second electrode 32b extends in the liquid crystal director direction), and one end of the second electrode 32b extends in the direction of the liquid crystal director of the design. If it is an edge part located in the reverse direction side, the 1st electrode 31b is extended from the one end part to the reverse direction side (the edge of the 1st electrode 31b is extended in the said reverse direction).

Specifically, for the first end 61, the second end 62, the fourth end 64, the seventh end 67, and the eighth end 68, the angle θ1 is + 54 ° and the angle θ2 is respectively. The angle of −54 °, θ4 is + 90 °, θ7 is + 90 °, and θ8 is + 90 °, satisfying the above-mentioned end angle conditions, and the first end 61 and the second end 62 are liquid crystals of the first design 60a. Since the seventh end 67 is located on the liquid crystal director direction side of the second design 60b, the second electrode 32b includes the first end 61, the second end 62, and the seventh end. The edge of each of 67 extends to the liquid crystal director direction side.
Further, the fourth end portion 64 is located on the opposite side to the liquid crystal director direction of the first design 60a, and the eighth end portion 68 is located on the opposite side to the liquid crystal director direction of the second design 60b. The first electrode 31b has edges extending from the fourth end portion 64 and the eighth end portion 68 in the direction opposite to the liquid crystal director direction.

  On the other hand, when the end angle does not satisfy the end angle condition, it is not necessary for both electrodes to have a shape / arrangement relationship peculiar to the present embodiment. For example, the shape of the electrode is determined according to the conventional design. Specifically, for the third end 63, the fifth end 65, and the sixth end 66, the angle θ3 is + 18 °, the angle θ5 is −18 °, and the angle θ6 is less than + 30 °. Since the corner angle condition is not satisfied, both electrodes at these end portions do not have a shape and arrangement relationship peculiar to the present embodiment.

When the electrode is extended from the end of the design as described above (that is, when the electrode is extended in the forward direction at the end of the design that satisfies the end angle condition), the extension length (extends the electrode) It is a length, and when viewed in plan, the distance between the edge of the target first electrode 31b and the edge of the second electrode 32b is arbitrary, but can reduce display abnormality. The direction in which the liquid crystal molecules 33a incline at the end satisfying the end angle condition can be set to the same length or longer than the predetermined length. This predetermined length is larger than the length of the shift (margin required in the overlaying process) caused by the overlay accuracy of the first electrode 31b and the second electrode 32b.
In addition, at the end of the design that does not satisfy the end angle condition, the electrode may not be extended (the edges of both electrodes overlap in a plan view), or may be a distance shorter than the predetermined length. For example, the electrode may be extended by the above-described forward extending relationship, or the electrode may be extended by a distance equal to or longer than the predetermined length as long as the above-described reverse extending relationship is established. In other words, at the end portion that does not satisfy the end portion corner condition, the electrode is not extended more than the predetermined length due to the forward extending relationship. Further, the electrodes at the ends of the design not specifically shown in the above specific examples are also formed and arranged in a forward extending relationship at the ends satisfying the end angle condition.

(About the connection width of the connection part)
In addition, in the liquid crystal display device 100, the inventor of the present application forms a connection width of the connection portion 323b, which is a routing electrode between the designs in the second electrode 32b (between the first design 60a and the second design 60b), to 100 μm or less. It has also been found that the occurrence of display abnormality visually recognized at the end of the design can be suppressed. In addition, a connection width means the width | variety of the direction perpendicular | vertical to the direction in which a connection part connects the 1st design 60a and the 2nd design 60b.

  Here, FIG. 5 shows an experimental result regarding the presence or absence of display abnormality when a liquid crystal display device is produced by changing the connection width of the connection portion 323b (80, 100, 150, 300 μm). In addition, this experimental result is a result when it arrange | positions without extending an electrode as mentioned above (that is, it corresponds substantially in the design end), and the frame frequency is 100 Hz.

As shown in the figure, when the connection width is 80 μm or 100 μm, a good result is obtained that no display abnormality is visually recognized at the design end in the vicinity of the connection portion 323b. On the other hand, when the connection width is 150 μm, the display abnormality is not completely recognized at the design end in the vicinity of the connection portion 323b. Further, when the connection width was 300 μm, a display abnormality was visually recognized at the design end in the vicinity of the connection portion 323b.
As described above, the inventor of the present application has found that the connection portion 323b may be formed with a connection width of “100 μm or less” in order to improve the display quality of the liquid crystal display device.

(About the pretilt angle of the liquid crystal layer)
Further, the inventor of the present application sets the pretilt angle applied to the liquid crystal layer 33 in the liquid crystal display device 100 as “85 ° or more and 89.7 ° or less”, more preferably “89 ° or more and 89.7 ° or less”. In other words, the inventors have thought that the display quality of the liquid crystal display device can be maintained while preventing so-called background loss.

  Here, in FIG. 6, when the liquid crystal display device is produced by changing some of the pretilt angles θp (83 °, 85 °, 89 °, 89.7 °, 90 °), the display abnormality and background loss are not observed. The experimental result regarding the presence or absence of occurrence is shown. Background loss refers to light leakage that occurs when no voltage is applied in a passive manner. FIG. 6 shows a state in which the viewing angle dependency deteriorates as θp decreases (the liquid crystal molecules 33a fall from the vertical state), and the circular graph in FIG. 6 shows no voltage applied at each pretilt angle. The distribution result of the transmittance (lower limit 0% to upper limit 0.5%) in the display area at the time is shown. If the transmittance is low, light leakage is small. Note that the display abnormality and background missing experimental results were arranged without extending the electrodes as described above (that is, substantially matched at the design end), and the frame frequency was set to 100 Hz only for the display abnormal experimental results. And when the voltage is applied.

  As shown in the figure, when the angle θp of the pretilt angle is other than 90 °, the display abnormality is not noticeable and is not visually recognized. However, when [theta] p is 83 [deg.], Background loss is conspicuous (in the circular graph, the area where the transmittance in the display area is high (area where the transmittance is near 0.5%) Hi is large), the display quality is high This angle cannot be adopted from the viewpoint of maintaining On the other hand, when θp was 85 ° or more and 89.7 ° or less, background loss did not occur conspicuously. As described above, it was found that when the pretilt angle of the liquid crystal layer 33 is “85 ° or more and 89.7 ° or less”, good display quality can be maintained. However, when [theta] p is 85 [deg.], The background omission is not noticeable and acceptable, and when the background omission is not problematic, [theta] p is preferably 89 [deg.] Or more. Therefore, the pretilt angle of the liquid crystal layer 33 is more preferably “89 ° or more and 89.7 ° or less”.

(Regarding the production method of the liquid crystal display device 100)
A method for producing the liquid crystal display device 100 will be described.
First, the 1st board | substrate 31a and the 2nd board | substrate 32a which consist of transparent substrates are prepared, and the 1st electrode 31b and the 2nd electrode 32b are formed with ITO on the one surface of both board | substrates.
The first electrode 31b and the second electrode 32b are liquid crystal whose end part angle satisfies the condition (end part angle condition) that the angle of the end part angle is “smaller than −30 ° or greater than +30”. If it is an end portion located on the director direction side, the second electrode 32b is extended from the one end portion thereof toward the liquid crystal director direction side (the edge of the second electrode 32b extends in the liquid crystal director direction), and one end portion thereof is designed. The first electrode 31b extends from one end thereof to the opposite direction side (the edge of the first electrode 31b extends in the opposite direction). Thus, the first electrode 31b and the second electrode 32b are formed through a determination step for determining the layout of the first electrode 31b and the layout of the second electrode 32b.
In other words, in this determination step, the absolute value of the angle with respect to the liquid crystal director direction is positioned on the liquid crystal director direction side with the first end portion whose absolute value with respect to the liquid crystal director direction is 30 ° or less, and the absolute value of the angle with respect to the liquid crystal director direction is greater than 30 °. And an end of the design including the second end, the edge of the second electrode 32b at the second end is a predetermined length or more in the liquid crystal director direction than the end of the first electrode 31b. In this step, the layout of the first electrode 31b and the layout of the second electrode 32b are determined so as to satisfy the condition of being extended.
In addition, this determination step is located on the side opposite to the liquid crystal director direction with respect to the first end where the absolute value of the angle with respect to the liquid crystal director direction is 30 ° or less, and the absolute value of the angle with respect to the liquid crystal director direction is 30. And an end portion of the design including a second end portion that is larger than 0 °, the end edge of the first electrode 32a at the second end portion has a predetermined length in the opposite direction to the end edge of the second electrode 32b. This is a step of determining the layout of the first electrode 31b and the layout of the second electrode 32b so as to satisfy the condition of being extended more than this.
Further, the connection width of the connection portion 323b which is a lead-out electrode between the designs in the second electrode 32b (between the first design 60a and the second design 60b) is formed to be 100 μm or less.

  Next, a first alignment film 31c is formed on the first substrate 31a so as to cover the first electrode 31b. Similarly, a second alignment film 32c is formed on the second substrate 32a so as to cover the second electrode 32b. The first alignment film 31c and the second alignment film 32c thus formed are rubbed so as to be antiparallel, for example, and the liquid crystal layer 33 is “85 ° or more and 89.7 ° or less”. Preferably, the pretilt of “89 ° to 89.7 °” is adjusted. In this way, the first substrate unit 31 and the second substrate unit 32 are formed.

  Next, a sealing material (not shown) and a gap control material (not shown) are applied to either the first substrate unit 31 or the second substrate unit 32, and the first substrate unit 31, the second substrate unit 32, Are stacked so that the electrode sides face each other. A liquid crystal material having a negative dielectric anisotropy Δε (Δε <0) is injected between the first substrate unit 31 and the second substrate unit 32 to form the liquid crystal layer 33, thereby forming the liquid crystal element 30. Create The liquid crystal molecules 33a of the liquid crystal layer 33 are vertically aligned with the first alignment film 31c and the second alignment film 32c and given the pretilt.

  Next, the 1st polarizing filter 10 and the 2nd polarizing filter 20 are bonded together to the liquid crystal element 30 produced as mentioned above. The first polarizing filter 10 and the second polarizing filter 20 are arranged in crossed Nicols so that each transmission axis (or absorption axis) has an angle of + 45 ° and −45 ° with respect to the liquid crystal director direction.

  The liquid crystal display device 100 is produced by forming the transflective layer 40 below the second polarizing filter 20 and disposing the backlight 50 below the semi-transmissive reflective layer 40.

  According to the vertical alignment type liquid crystal display device 100 produced in this way, the alignment defects that occur as described above can be suppressed. Therefore, according to FIGS. Occurrence of display abnormality (see FIGS. 9 (a) and 9 (b)) that was visually recognized in the area could be eliminated or reduced. In addition, according to the liquid crystal display device 100 designed and produced as in the present embodiment, the alignment stability of the liquid crystal layer 33 is improved, and is generated when a conventional voltage is applied as shown in FIG. It was found that the occurrence of shadow-like display unevenness (see FIG. 9C) can be suppressed. In this way, good display quality can be maintained.

(Modification)
In addition, this invention is not limited by said embodiment and drawing. It goes without saying that changes (including deletion of components) can be added to the above embodiments and drawings.
For example, in the above description, the liquid crystal display device 100 is described as a semi-reflective liquid crystal display device including the semi-transmissive reflective layer 40, but is not limited thereto. The transflective layer 40 may be omitted to provide a transmissive liquid crystal display device, or the transflective layer 40 may be a reflective liquid crystal display device as a reflective layer. In the case of the reflection type, the backlight 50 is not necessary. Moreover, in the above description, in order to make an understanding of this invention easy, description of the known technical matter which is not important was abbreviate | omitted suitably.

  In the above description, the second electrode 32b has been described as having an electrode pattern formed in a shape substantially equal to the shape of the design. However, the roles of the first electrode 31b and the second electrode 32b may be reversed.

  In the above description, the end of the design (design outline) is a side (straight line). However, the end of the design is a curved line such as an arc (that is, the edge of the electrode is curved). The present invention is also applicable in the same manner. When the end of the design is a curve, the angle between the tangent to the end of the design and the liquid crystal director may be the end angle.

DESCRIPTION OF SYMBOLS 100 Liquid crystal display device 10 1st polarizing filter 20 2nd polarizing filter 30 Liquid crystal element 31 1st board | substrate unit 31a 1st board | substrate 31b 1st electrode 311b 1st part 31c 1st alignment film 32 2nd board | substrate unit 32a 2nd board | substrate 32b Second electrode 32c Second alignment film 33 Liquid crystal layer 33a Liquid crystal molecule 40 Transflective layer 50 Backlight 60a First design 60b Second design 61 First end 62 Second end 63 Third end 64 Fourth end 65 5th end 66 6th end 67 7th end 68 8th end

Claims (9)

A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. An alignment type liquid crystal display device,
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end portion of the design is located on the liquid crystal director direction side with the first end portion having an absolute value of an angle with respect to the liquid crystal director direction being equal to or less than a predetermined value, and the absolute value of the angle with respect to the liquid crystal director direction is A second end greater than a predetermined value,
The edge of the second electrode at the second end is extended by a predetermined length or more in the liquid crystal director direction than the edge of the first electrode.
A vertical alignment type liquid crystal display device. A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. An alignment type liquid crystal display device,
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end of the design is located on the side opposite to the first end where the absolute value of the angle relative to the liquid crystal director direction is equal to or less than a predetermined value, and the angle relative to the liquid crystal director direction. A second end having an absolute value greater than the predetermined value;
The edge of the first electrode at the second end is extended more than a predetermined length in the opposite direction than the edge of the second electrode.
A vertical alignment type liquid crystal display device. The predetermined value is 30 °.
The vertical alignment type liquid crystal display device according to claim 1, wherein the liquid crystal display device is a vertical alignment type liquid crystal display device. The first alignment film is rubbed in one direction, and the second alignment film is rubbed in a direction opposite to the one direction, thereby defining a direction in which the liquid crystal molecules are tilted. Yes,
The vertical alignment liquid crystal display device according to claim 1, wherein the liquid crystal display device is a vertical alignment liquid crystal display device. In the case where there are a plurality of regions where the two electrodes substantially overlap and there are a plurality of designs to be displayed, the first electrode is a connecting portion for connecting a first design display region and a second design display region. And / or the width of the connection part of the second electrode is 100 μm or less,
The vertical alignment type liquid crystal display device according to claim 1, wherein the liquid crystal display device is a vertical alignment type liquid crystal display device. The pretilt angle of the liquid crystal layer is 85 ° or more and 89.7 ° or less.
The vertical alignment type liquid crystal display device according to claim 1, wherein the liquid crystal display device is a vertical alignment type liquid crystal display device. The pretilt angle of the liquid crystal layer is 89 ° or more and 89.7 ° or less.
The vertical alignment type liquid crystal display device according to claim 6. A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. A method for producing an alignment type liquid crystal display device,
Determining a layout of the first electrode and a layout of the second electrode;
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end portion of the design is located on the liquid crystal director direction side with the first end portion having an absolute value of an angle with respect to the liquid crystal director direction being equal to or less than a predetermined value, and the absolute value of the angle with respect to the liquid crystal director direction is A second end greater than a predetermined value,
The determining step satisfies a condition that an edge of the second electrode at the second end is extended by a predetermined length or more in the liquid crystal director direction than an edge of the first electrode. Determining the layout of the first electrode and the layout of the second electrode;
A method for producing a vertical alignment type liquid crystal display device. A first substrate;
A second substrate located under the first substrate and facing the first substrate;
A first electrode formed on a lower surface of the first substrate;
A first alignment film formed on the first substrate so as to cover the first electrode from below;
A second electrode formed on the upper surface of the second substrate;
A second alignment film formed on the second substrate so as to cover the second electrode from above;
A liquid crystal layer positioned between the first alignment film and the second alignment film,
In a state where no voltage is applied to both the first electrode and the second electrode, the liquid crystal molecules of the liquid crystal layer are aligned substantially perpendicular to the opposing surfaces of the first substrate and the second substrate,
A vertical display of a design constituted by a region where the two electrodes are substantially overlapped when viewed from the normal direction of the facing surface, when the liquid crystal molecules of the liquid crystal layer are tilted in response to applying a voltage to the two electrodes. A method for producing an alignment type liquid crystal display device,
Determining a layout of the first electrode and a layout of the second electrode;
When the direction in which the angle of the pretilt angle of the liquid crystal molecules with respect to the second substrate is reduced as viewed from the normal direction is the liquid crystal director direction,
The end of the design is located on the side opposite to the first end where the absolute value of the angle relative to the liquid crystal director direction is equal to or less than a predetermined value, and the angle relative to the liquid crystal director direction. A second end having an absolute value greater than the predetermined value;
The determination step satisfies the condition that an edge of the first electrode at the second end is extended by a predetermined length or more in the opposite direction from an edge of the second electrode. Determining the layout of the first electrode and the layout of the second electrode;
A method for producing a vertical alignment type liquid crystal display device.

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