JP4777795B2 - Liquid crystal display element - Google Patents

Description

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal Display device of a vertical alignment mode.

  The liquid crystal display element has a relatively simple structure, can be easily reduced in thickness and weight by selecting the constituent members, and can be driven at a low voltage. For this reason, in recent years, it is actively used for computers, televisions, video cameras, vehicle instrument panels, and the like.

  For example, in a transmissive liquid crystal display element, a very thin liquid crystal layer of about several μm oriented in a predetermined direction, a pair of transparent thin substrates that sandwich the liquid crystal layer, and a polarizer that sandwiches the substrate And a pair of polarizing plates constituting the analyzer. An electrode patterned in a predetermined shape is formed on the substrate surface on the side where the liquid crystal layer is provided. When a voltage is applied to the liquid crystal layer through this electrode, the alignment of the liquid crystal changes, and the amount or wavelength of light transmitted through the liquid crystal display element changes. In the liquid crystal display element, desired display is performed using this.

  Such liquid crystal display elements are classified into several modes according to the initial alignment state of the liquid crystal layer, the operation state and the alignment state when a voltage is applied, and the like. For example, one of liquid crystal display elements used for an instrument panel of a vehicle such as an automobile is a vertical alignment (hereinafter referred to as VA) mode.

  In the VA mode liquid crystal display element, a liquid crystal layer having a negative dielectric anisotropy (Δε) whose initial alignment state is substantially perpendicular to the substrate (vertical alignment) is sandwiched between a pair of substrates. Usually, it is comprised by pinching with a pair of polarizing plate arrange | positioned so that cross Nicole may be comprised. When a voltage is applied to the liquid crystal layer through the electrode formed on the substrate surface, the alignment of the liquid crystal changes, and the liquid crystal layer is perpendicular to the electric field, that is, the alignment direction of the liquid crystal is parallel to the substrate. Thereby, the light transmission characteristics determined by the product (Δn · d) of the refractive index anisotropy (Δn) of the liquid crystal and the liquid crystal layer thickness (d) between the portion where the voltage is applied and the portion where the voltage is not applied, Can make a difference in color.

  By the way, in the liquid crystal display element, each liquid crystal layer is sandwiched between the substrates so that the liquid crystal is aligned substantially perpendicular to the substrate and the operation direction of the liquid crystal is uniform when a voltage is applied. An orientation treatment is performed. At this time, in the VA mode liquid crystal display element, the initial alignment of the liquid crystal in the liquid crystal layer is not completely perpendicular to the substrate but slightly inclined. That is, the major axis direction of the liquid crystal molecules has a very small angle (pretilt angle) between the normal direction. When a voltage is applied, the liquid crystal operates in a direction in which the pretilt angle increases, and as a result, the liquid crystal is aligned substantially parallel to the substrate.

  However, when the liquid crystal is aligned as described above, the tilt angle of the liquid crystal molecules varies depending on the direction in which the liquid crystal display element is viewed. For this reason, there is a problem that the luminance and contrast of the liquid crystal display element change depending on the viewing angle direction.

  On the other hand, when a voltage is applied to the liquid crystal layer by providing a plurality of openings in the pixel electrode for an active matrix substrate in which an insulating film, a pixel electrode, and an alignment film are sequentially formed on a transparent substrate. A liquid crystal display element has been proposed in which electric lines of force around the opening are tilted with respect to the substrate, thereby aligning liquid crystal molecules around the opening so as to fall radially around the opening (see Patent Document 1). ). According to this liquid crystal display element, the liquid crystal molecules around the opening are aligned in an axially symmetrical manner, so that display characteristics with a wide viewing angle can be realized.

  In addition, a liquid crystal display element in which slits are provided in each of a pair of transparent substrates sandwiching a liquid crystal layer, and these slits are alternately arranged in a direction perpendicular to the longitudinal direction of the slits in the display region has been proposed ( Patent Document 2). According to this liquid crystal display element, the slant electric field generated near the edge of the slit alternately reverses the direction in which the adjacent liquid crystal molecules fall, and the small region with the best viewing state is the most visible state in any viewing angle direction. It is supposed that the viewing angle dependency of the entire display area can be reduced because the compensation is made by the small area having a poor quality.

  Further, a liquid crystal display element in which a slit is provided in an electrode of one substrate and a protrusion is provided in an electrode of the other substrate has been proposed (see Patent Document 3). In this liquid crystal display element, when a voltage is applied, an oblique electric field is generated in the slit portion with respect to the substrate surface, and liquid crystal molecules are inclined in the protrusion portion. Since the alignment direction of the liquid crystal is divided in the middle of the slit portion and the projection portion, uniform halftone display can be obtained in all directions.

Japanese Patent No. 3367902 JP 2004-252298 A Japanese Patent No. 2947350

  However, in the liquid crystal display elements described in Patent Documents 1 to 3, an opening or a slit must be provided in the electrode, and patterning of the electrode using a photolithography method or the like is necessary. For this reason, the number of processes is increased, and there is a problem in that the yield is reduced and the cost is increased.

  Further, in a passive matrix liquid crystal display element capable of performing character display, the electrode structure is not a dense dot matrix structure, the aperture ratio of the display portion is 70% or less, and no electrode is formed in the display portion. The structure has a large area. For this reason, it has been difficult to design and manufacture the electrode structures described in Patent Documents 1 to 3.

  By the way, as described above, when the voltage between the electrodes of the liquid crystal display element is increased, the major axis of the liquid crystal molecules starts to tilt from around a certain threshold voltage. In the region from the threshold voltage to the saturation voltage, the amount of light transmitted through the liquid crystal layer is continuously changed by the applied voltage. Here, in order to perform duty driving with a passive matrix liquid crystal display element, a steep threshold characteristic is required for the operation of liquid crystal molecules. In this case, when the pretilt angle is lowered, the steepness is lowered and sufficient transmittance cannot be obtained when a voltage is applied. Therefore, in order to improve the steepness of the liquid crystal display element, it is necessary to increase the pretilt angle.

  When the projection is provided on the electrode, the liquid crystal molecules tend to be aligned perpendicular to the slope of the projection, so the pretilt angle of the liquid crystal molecules depends on the shape of the projection. For this reason, the structure of the liquid crystal display element described in Patent Document 3 has a problem that it is difficult to increase the pretilt angle of liquid crystal molecules and it is difficult to perform duty driving.

  The present invention has been made in view of these problems. That is, an object of the present invention is to provide a liquid crystal display element having a wide viewing angle and suitable for performing duty driving.

  Another object of the present invention is to provide a method capable of easily producing a liquid crystal display element having a wide viewing angle as compared with the conventional method.

  Other objects and advantages of the present invention will become apparent from the following description.

The first aspect of the present invention includes a pair of substrates each having an electrode layer formed on each of the opposing surfaces, and a liquid crystal layer sandwiched between the pair of substrates, and the liquid crystal via the electrode layer In a liquid crystal display element that displays an image on the display unit by applying a voltage to the layer,
The opposing surfaces of the pair of substrates are each provided with an alignment film that is vertically aligned and has been subjected to an alignment process in a predetermined region. The alignment film of one alignment film and the other The regions subjected to the alignment treatment of the alignment film are alternately arranged in one direction without overlapping each other.

According to a second aspect of the present invention, there is provided a pair of substrates each having an electrode layer formed on each of opposing surfaces, and a liquid crystal layer sandwiched between the pair of substrates, and the liquid crystal via the electrode layer In a liquid crystal display element that displays an image on the display unit by applying a voltage to the layer,
The opposing surfaces of the pair of substrates are each provided with a vertical alignment film, and one alignment film is subjected to an alignment process in which the alignment directions are alternately reversed with respect to one direction. The alignment film is not subjected to alignment treatment.

  In the first and second aspects of the present invention, the liquid crystal display element may be a passive matrix liquid crystal display element.

According to a third aspect of the present invention, there is provided a pair of substrates each having an electrode layer formed on each of the opposing surfaces, and a liquid crystal layer sandwiched between the pair of substrates, and the liquid crystal via the electrode layer In a method for manufacturing a liquid crystal display element that displays an image on a display unit by applying a voltage to a layer,
Forming a vertical alignment first alignment film on one of the pair of substrates;
Forming a vertical alignment second alignment film on the other substrate of the pair of substrates;
Performing a first rubbing treatment on the first alignment film;
Performing a second rubbing treatment on the second alignment film,
The first rubbing process and the second rubbing process are performed such that, when the pair of substrates face each other, the regions where these rubbing processes are performed are alternately arranged in one direction without overlapping each other. It is characterized by that.

According to a fourth aspect of the present invention, there is provided a pair of substrates each having an electrode layer formed on each opposing surface, and a liquid crystal layer sandwiched between the pair of substrates, and the liquid crystal via the electrode layer In a method for manufacturing a liquid crystal display element that displays an image on a display unit by applying a voltage to a layer,
Forming a vertical alignment first alignment film on one of the pair of substrates;
Forming a vertical alignment second alignment film on the other substrate of the pair of substrates;
Performing a first rubbing treatment on the first alignment film;
A step of subjecting the first alignment film to a second rubbing treatment in which the orientation direction is opposite to the first rubbing treatment;
The first rubbing process and the second rubbing process are performed such that regions where these rubbing processes are performed are alternately arranged in one direction without overlapping each other.

  According to the first aspect of the present invention, the region subjected to the alignment treatment of one alignment film and the region subjected to the alignment treatment of the other alignment film are alternately arranged in one direction without overlapping each other. Has been. For this reason, when a voltage is applied to the liquid crystal layer, the alignment directions of the liquid crystal molecules are reversed between the first domain and the second domain. Therefore, since the viewing angle dependency in each region is complemented, a liquid crystal display element having a wide viewing angle can be obtained. In addition, since the electrode is not provided with a protrusion, the pretilt angle can be easily increased, and a liquid crystal display element suitable for duty driving can be obtained.

  According to the second aspect of the present invention, one alignment film is subjected to an alignment treatment in which the alignment directions are alternately reversed in one direction, but the other alignment film is not subjected to the alignment treatment. . For this reason, when a voltage is applied to the liquid crystal layer, the alignment directions of the liquid crystal molecules are reversed between the first domain and the second domain. Therefore, since the viewing angle dependency in each region is complemented, a liquid crystal display element having a wide viewing angle can be obtained. In addition, since the electrode is not provided with a protrusion, the pretilt angle can be easily increased, and a liquid crystal display element suitable for duty driving can be obtained.

  According to the third aspect of the present invention, when the first rubbing process and the second rubbing process are performed, when the pair of substrates face each other, the regions where these rubbing processes are performed do not overlap each other in one direction. It is performed so as to be arranged alternately. For this reason, when a voltage is applied to the liquid crystal layer, the orientation directions of the liquid crystal molecules are reversed in the first domain and the second domain, and the viewing angle dependency in each region is complemented. Therefore, a liquid crystal display element with a wide viewing angle can be manufactured.

  According to the fourth aspect of the present invention, the first rubbing process and the second rubbing process are performed such that the regions where these rubbing processes are performed are alternately arranged in one direction without overlapping each other. . For this reason, when a voltage is applied to the liquid crystal layer, the orientation directions of the liquid crystal molecules are reversed in the first domain and the second domain, and the viewing angle dependency in each region is complemented. Therefore, a liquid crystal display element with a wide viewing angle can be manufactured.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view of a liquid crystal display element in the present embodiment. As shown in this figure, the liquid crystal display element is sandwiched between a first substrate 1, a second substrate 2 facing the first substrate 1, and the first substrate 1 and the second substrate 2. And a liquid crystal layer 4 composed of liquid crystal molecules 11 having a dielectric anisotropy of 5. Here, the first substrate 1 can be a TFT substrate, and the second substrate 2 can be a color filter substrate.

  Further, the liquid crystal display element includes a viewer-side polarizing plate 5 and an anti-viewer-side polarizing plate 6. These are provided on the surface opposite to the surface facing the liquid crystal layer 3 in the first substrate 1 and the second substrate 2, and are arranged in a crossed Nicol arrangement with the liquid crystal cell 4 interposed therebetween. Incidentally, the crossed Nicol arrangement means an arrangement in which the crossing angle between the absorption axis of one polarizing plate and the absorption axis of the other polarizing plate is 90 ° ± 5 °.

  On the other hand, on the surface of the first substrate 1 on the side where the liquid crystal layer 3 is provided, a first electrode layer 7 for applying a voltage to the liquid crystal layer 3 and a first vertical for controlling the initial alignment direction of the liquid crystal. The alignment film 8 is formed in this order. The second electrode layer 9 for applying a voltage to the liquid crystal layer 3 and the second vertical layer for controlling the initial alignment direction of the liquid crystal are also applied to the surface of the second substrate 2 on the side where the liquid crystal layer 3 is provided. The alignment film 10 is formed in this order. The vertical alignment film refers to a vertical alignment film (hereinafter the same in this specification).

  In the present embodiment, the first vertical alignment film 8 and the second vertical alignment film 10 are subjected to an alignment process in predetermined regions. The region where the first vertical alignment film 8 is subjected to the alignment treatment and the region where the second vertical alignment film 10 is subjected to the alignment treatment are alternately arranged in one direction without overlapping each other. It is characterized by that. In the example of FIG. 1, a rubbing process is performed on a predetermined region of the first vertical alignment film 8 from the right to the left in the drawing. On the other hand, the second vertical alignment film 10 is a region that does not overlap with the region rubbed by the first vertical alignment film 8 and is adjacent to the rubbed region. A rubbing process is performed in the direction.

  By doing as described above, when no voltage is applied to the liquid crystal layer 3, the liquid crystal molecules 11 are formed on the surfaces of the first vertical alignment film 8 and the second vertical alignment film 10 that are not rubbed. Oriented perpendicular to On the other hand, the liquid crystal molecules 11 are aligned with a pretilt angle from the normal direction with respect to the surfaces of the first vertical alignment film 8 and the second vertical alignment film 10 subjected to the rubbing treatment. In the present embodiment, the pretilt angle is preferably 1 degree or less.

Thus, when the liquid crystal molecules 11 exhibit different alignments, the liquid crystal layer 3 has two domains having different alignment directions in one pixel. That is, in the first domain D ₁ , the liquid crystal molecules 11 are aligned perpendicular to the surface of the first substrate 1, but are aligned with a pretilt angle with respect to the surface of the second substrate 2. On the other hand, in the second domain D ₂ , the liquid crystal molecules 11 are aligned with a pretilt angle with respect to the surface of the first substrate 1, but are aligned perpendicular to the surface of the second substrate 2.

FIG. 2 is a diagram showing a state in which a voltage is applied to the liquid crystal layer 3 through the first electrode layer 7 and the second electrode layer 9 in the liquid crystal display element of FIG. When a voltage is applied to the liquid crystal layer 3, the liquid crystal molecules 11 are tilted in the direction in which the pretilt angle is increased. Therefore, the first domain D _1, the liquid crystal molecules toward the right direction from the left in FIG. 2 tilted. On the other hand, in the second domain D _2, the liquid crystal molecules from the right FIG. 2 toward the left inclined.

  As described above, in the liquid crystal display element of this embodiment, one pixel is divided into two regions to form two regions (first domain and second domain) having different alignment directions. Therefore, when a voltage is applied to the liquid crystal layer, the orientation directions of the liquid crystal molecules are reversed in the first domain and the second domain, so that the viewing angle dependency in each region is complemented, and the entire display region is The viewing angle dependency can be reduced. Therefore, a liquid crystal display element having a wide viewing angle can be obtained.

  In addition, since the liquid crystal display element of this embodiment has a structure in which no protrusion is provided on the electrode, it is easy to increase the pretilt angle, and it can be an element suitable for duty driving.

  Next, a method for manufacturing a liquid crystal display element in the present embodiment will be described.

  First, a pair of glass substrates is prepared as the first substrate 1 and the second substrate 2. Next, a first electrode layer 7 and a second electrode layer 9 that are patterned so as to perform desired image display such as character display are provided on one surface of these substrates. The first electrode layer 7 and the second electrode layer 9 can be, for example, ITO (Indium Tin Oxide) electrodes.

  Next, a first vertical alignment film 8 is provided on the first substrate 1 so as to cover the first electrode layer 7. Similarly, the second vertical alignment film 10 is provided on the second substrate 2 so as to cover the second electrode layer 9. For example, an alignment film having a thickness of about 600 mm can be formed by forming an alignment film material (trade name: JALS-2021) manufactured by JSR Corporation by flexographic printing and baking the substrate at 180 ° C. it can.

  Next, an alignment process is performed on the first vertical alignment film 8 and the second vertical alignment film 10. Thereby, the operation direction of the liquid crystal when an electric field is applied, that is, the alignment direction of the liquid crystal layer when a voltage is applied can be determined.

  In the present embodiment, the first vertical alignment film 8 and the second vertical alignment film 10 are each subjected to alignment processing in predetermined regions. However, these alignment treatments are performed such that when the first substrate 1 and the second substrate 2 face each other, the regions subjected to the alignment treatment are alternately arranged in one direction without overlapping each other. And

  The alignment treatment can be, for example, a mask rubbing method, a mask light alignment method, or a mask oblique deposition method. In the present embodiment, a mask rubbing method will be described as an example. In this case, in addition to using a hard mask such as a metal mask as a mask, the mask may be formed by a photolithography method, a flexographic printing method, a screen printing method, or the like. However, it is preferable to use a hard mask from the viewpoint of preventing an increase in the number of steps.

  The orientation processing method in the present embodiment will be described with reference to FIGS. In these drawings, the same reference numerals as those in FIGS. 1 and 2 are the same.

For example, a stainless metal mask provided with a predetermined opening is used as a hard mask, and a portion corresponding to the second domain D ₂ of the first vertical alignment film 8 is used as shown in FIG. The metal mask 12 is aligned and fixed so that the opening of the metal mask 12 corresponds. Thus, a portion corresponding to a second domain D ₂ is in a state of being exposed from the metal mask 12, a portion corresponding to the first domain D ₁ is in the state of being covered by the metal mask 12.

Next, a rubbing roller on which an appropriate rubbing cloth is wound is prepared. Then, as shown in FIG. 3B, the rubbing roller 13 is rotated clockwise on the first vertical alignment film 8 through the metal mask 12, and the first substrate 1 is moved from the right to the left in the drawing. Move in the direction of. Thus, with respect to the first vertical alignment film 8, it performs a rubbing process only a portion corresponding to a second domain D _2, the portion corresponding to the first domain D ₁ so as not to rubbing treatment can do. In addition, the moving speed of the 1st board | substrate 1, the rotation speed of the rubbing roller 13, the pushing amount of the rubbing roller 13, etc. can be set suitably.

Similarly, the rubbing process is performed on the second vertical alignment film 10. That is, as shown in FIG. 4 (a), the openings of the metal mask 14 is fixed in alignment so as to correspond to the portion corresponding to the first domain D ₁ of the second vertical alignment film 10. Thus, a portion corresponding to the first domain D ₁ is in a state of being exposed from the metal mask 14, a portion corresponding to a second domain D ₂ is in the state of being covered by the metal mask 14.

Next, as shown in FIG. 4B, the rubbing roller 13 is rotated counterclockwise on the second vertical alignment film 10 through the metal mask 14, and the second substrate 2 is moved to the left of the drawing. Move to the right. Thus, with respect to the second vertical alignment film 10, subjected to rubbing treatment only in a portion corresponding to the first domain D _1, the portion corresponding to the second domain D ₂ so as not to rubbing treatment can do.

  Next, the first substrate 1 and the second substrate 2 are bonded together to assemble a liquid crystal cell. At this time, the side where the first vertical alignment film 8 is formed and the side where the second vertical alignment film 10 is formed are overlapped so as to face inward. Then, the portion where the rubbing process is performed on the first vertical alignment film 8 and the portion where the rubbing process is performed on the second vertical alignment film 10 are alternately arranged in one direction without overlapping each other. Will face each other. In addition, by sandwiching a spacer (not shown) such as a resin between the first substrate 1 and the second substrate 2, the distance (d) between the substrates can be kept constant.

  Next, liquid crystal molecules 11 having negative dielectric anisotropy are injected and sealed between the first substrate 1 and the second substrate 2. For example, when d = 4 μm and liquid crystal molecules having a refractive index anisotropy (Δn) of 0.0875 are used, the retardation (Δn · d) of the liquid crystal display element is 350 nm.

  Next, the polarizing plates 5 and 6 are installed. Specifically, the liquid crystal cell 1 is sandwiched and pasted so that the polarizing plates 5 and 6 are in a crossed Nicols arrangement. At this time, the polarizing plate 5 or the polarizing plate 6 may be pasted so that the absorption axis of the polarizing plate 5 and the operation direction of the liquid crystal molecules when an electric field is applied, that is, the alignment direction of the liquid crystal molecules when a voltage is applied, form an angle of 45 degrees. it can.

  Although not shown in detail, the liquid crystal display element in this embodiment can be a dot matrix display using dynamic drive. In this case, the liquid crystal display element can have a passive matrix structure. That is, it is possible to display a target image by passive driving using an electrode layer without providing a switching element such as a TFT in each pixel portion constituting the image display.

  Moreover, the liquid crystal display element in this Embodiment can also be set as a segment display.

  Furthermore, the liquid crystal display element in the present embodiment may be composed of both a dot matrix display having a passive matrix structure and a segment display.

  5 and 6 show the viewing angle dependence of the optical characteristics obtained by driving the liquid crystal display element of the present embodiment. As a comparative example, FIG. 7 and FIG. 8 show the viewing angle dependency of a conventional liquid crystal display element having only one domain.

  5 and 7 are isocontrast curves, and a portion surrounded by a solid line corresponds to a region having a contrast of 100 or more. The evaluation was performed using simulation software (LCD MASTER Ver. 6.14) manufactured by Shintech Co., Ltd.

  6 and 8 are diagrams showing the viewing angle dependence of the transmittance at the time of voltage application, that is, the ON transmittance, and a portion surrounded by a solid line corresponds to a region where the transmittance is 10% or more. The evaluation was performed using simulation software (LCD MASTER Ver. 6.14) manufactured by Shintech Co., Ltd.

  5 to 8, the center of the circle indicates the normal direction of the liquid crystal display element, the radius indicates the inclination angle from the normal direction to 80 degrees, and the number indicates the azimuth angle.

5 to 8, the distance d between the substrates is 4.5 μm, the refractive index anisotropy (Δn) of the liquid crystal is 0.09, and the retardation (Δn · d) of the liquid crystal display element is 405 nm. Further, with the horizontal direction as a reference (0 degree), the direction of the absorption axis of the polarizing plate on the viewer side was set to 135 degrees, and the direction of the absorption axis of the polarizing plate on the anti-viewer side was set to 45 degrees. Furthermore, one wide viewing angle film was provided between the polarizing plate on the viewer side and the liquid crystal cell. This wide viewing angle film has refractive index anisotropy, and the main refractive indexes in the x-axis, y-axis, and z-axis direction, which is the thickness direction of the liquid crystal cell, orthogonal to each other are denoted by _nx , _ny, and _nz. R _th = ((n _x + n _y ) / 2−n _z ) × (thickness of liquid crystal layer) = 340 nm. The liquid crystal display element is driven under the conditions of 1/4 duty (Duty) and 1/3 bias (Bias).

  5 to 8, it can be seen that according to the liquid crystal display element of the present embodiment, good viewing angle characteristics can be obtained in any direction.

Embodiment 2. FIG.
In the first embodiment, the first vertical alignment film and the second vertical alignment film are subjected to alignment treatment in regions alternately arranged in one direction without overlapping each other. On the other hand, the present embodiment is characterized in that only one vertical alignment film is subjected to alignment treatment, and the other vertical alignment film is not subjected to alignment treatment. Also in this case, a liquid crystal layer having two domains having different alignment directions in one pixel can be obtained.

  FIG. 9 is a partial cross-sectional view of the liquid crystal display element in the present embodiment. As shown in this figure, the liquid crystal display element is sandwiched between a first substrate 21, a second substrate 22 opposite to the first substrate 21, and the first substrate 21 and the second substrate 22. And a liquid crystal layer 24 composed of a liquid crystal molecule 31 having a dielectric anisotropy of 2. Here, the first substrate 21 can be a TFT substrate, and the second substrate 22 can be a color filter substrate.

  In addition, the liquid crystal display element includes a viewer-side polarizing plate 25 and an anti-viewer-side polarizing plate 26. These are provided on the surface of the first substrate 21 and the second substrate 22 opposite to the surface facing the liquid crystal layer 23, and are arranged in a crossed Nicol arrangement with the liquid crystal cell 24 interposed therebetween. Incidentally, the crossed Nicol arrangement means an arrangement in which the crossing angle between the absorption axis of one polarizing plate and the absorption axis of the other polarizing plate is 90 ° ± 5 °.

  On the other hand, on the surface of the first substrate 21 on the side where the liquid crystal layer 23 is provided, a first electrode layer 27 for applying a voltage to the liquid crystal layer 23 and a first vertical for controlling the initial alignment direction of the liquid crystal. The alignment film 28 is formed in this order. The second electrode layer 29 for applying a voltage to the liquid crystal layer 23 and the second vertical layer for controlling the initial alignment direction of the liquid crystal are also applied to the surface of the second substrate 22 on the side where the liquid crystal layer 23 is provided. The alignment film 30 is formed in this order.

  In the present embodiment, the second vertical alignment film 30 is subjected to an alignment process in which the alignment directions are alternately reversed in one direction. On the other hand, the first vertical alignment film 28 is not subjected to alignment treatment. In the example of FIG. 9, in the second vertical alignment film 30, the first rubbing process is performed from the right to the left in the drawing, and the second rubbing from the left to the right in the drawing. The regions where the rubbing process has been performed appear alternately.

  By doing as described above, when no voltage is applied to the liquid crystal layer 23, the liquid crystal molecules 31 are aligned perpendicular to the surface of the first vertical alignment film 28 that has not been subjected to the rubbing treatment. On the other hand, the liquid crystal molecules 31 are aligned with a pretilt angle from the normal direction with respect to the surface of the second vertical alignment film 30 subjected to the rubbing treatment. At this time, the liquid crystal molecules 31 include those that are inclined from the left to the right in FIG. 9 and those that are inclined from the right to the left in FIG. Thereby, the liquid crystal layer 23 has two domains having different alignment directions in one pixel. In the present embodiment, the pretilt angle is preferably 1 degree or less.

Thus, when the liquid crystal molecules 31 exhibit different orientations, the liquid crystal layer 23 has two domains having different orientation directions in one pixel. That is, in the first domain D ₁ , the liquid crystal molecules 31 are aligned with an inclination from the left to the right with respect to the surface of the second substrate 22. On the other hand, in the second domain D ₂ , the liquid crystal molecules 31 are aligned with an inclination from the right to the left with respect to the surface of the second substrate 22. In any domain, the liquid crystal molecules 31 are aligned perpendicular to the surface of the first substrate 21.

FIG. 10 is a diagram showing a state in which a voltage is applied to the liquid crystal layer 23 via the first electrode layer 27 and the second electrode layer 29 in the liquid layer display element of FIG. When a voltage is applied to the liquid crystal layer 23, the liquid crystal molecules 31 are tilted in the direction in which the pretilt angle is increased. Therefore, the first domain D _1, the liquid crystal molecules 31 from left to right in FIG. 10 is inclined. On the other hand, in the second domain D _2, the liquid crystal molecules 31 in the direction from right to left in FIG. 10 is inclined.

  As described above, in the liquid crystal display element of this embodiment as well, in the liquid crystal display element of this embodiment, one pixel is divided into two regions to form two regions (first domain and second domain) having different alignment directions. ing. Therefore, when a voltage is applied to the liquid crystal layer, the orientation directions of the liquid crystal molecules are reversed in the first domain and the second domain, so that the viewing angle dependency in each region is complemented, and the entire display region is The viewing angle dependency can be reduced. Therefore, a liquid crystal display element having a wide viewing angle can be obtained.

  In addition, since the liquid crystal display element of this embodiment has a structure in which no protrusion is provided on the electrode, it is easy to increase the pretilt angle, and it can be an element suitable for duty driving.

  Next, a method for manufacturing a liquid crystal display element in the present embodiment will be described.

  First, a pair of glass substrates is prepared as the first substrate 21 and the second substrate 22. Next, a first electrode layer 27 and a second electrode layer 29 that are patterned so as to display a desired image such as a character display are provided on one surface of these substrates. The first electrode layer 27 and the second electrode layer 29 can be, for example, ITO (Indium Tin Oxide) electrodes.

  Next, a first vertical alignment film 28 is provided on the first substrate 21 so as to cover the first electrode layer 27. Similarly, the second vertical alignment film 30 is provided on the second substrate 22 so as to cover the second electrode layer 29. For example, an alignment film having a thickness of about 600 mm can be formed by forming an alignment film material (trade name: JALS-2021) manufactured by JSR Corporation by flexographic printing and baking the substrate at 180 ° C. it can.

  Next, an alignment process is performed on the second vertical alignment film 30. Thereby, the operation direction of the liquid crystal when an electric field is applied, that is, the alignment direction of the liquid crystal layer when a voltage is applied can be determined.

  In the present embodiment, the alignment process is performed twice on the second vertical alignment film 30. These alignment treatments are performed so that the regions subjected to the alignment treatment are alternately arranged in one direction without overlapping each other.

  The alignment treatment can be, for example, a mask rubbing method, a mask light alignment method, or a mask oblique deposition method. In the present embodiment, a mask rubbing method will be described as an example. In this case, in addition to using a hard mask such as a metal mask as a mask, the mask may be formed by a photolithography method, a flexographic printing method, a screen printing method, or the like. However, it is preferable to use a hard mask from the viewpoint of preventing an increase in the number of steps.

  The alignment processing method in the present embodiment will be described with reference to FIGS. In these drawings, the same reference numerals as those in FIGS. 9 and 10 are the same.

For example, a stainless steel metal mask provided with a predetermined opening is used as a hard mask, and a portion corresponding to the first domain D ₁ of the second vertical alignment film 30 is used as shown in FIG. The metal mask 32 is positioned and fixed so that the openings correspond to each other. Thus, a portion corresponding to the first domain D ₁ is in a state of being exposed from the metal mask 32, a portion corresponding to a second domain D ₂ is in the state of being covered by the metal mask 32.

Next, a rubbing roller on which an appropriate rubbing cloth is wound is prepared. Then, as shown in FIG. 11B, the rubbing roller 33 is rotated counterclockwise on the second vertical alignment film 30 through the metal mask 32, and the second substrate 22 is moved from the left in the drawing. Move to the right. Thus, with respect to the second vertical alignment film 30, only the portion corresponding to the first domain D ₁ performs a first rubbing process, the portion corresponding to the second domain D ₂ first rubbing It is possible to prevent processing. The moving speed of the second substrate 22, the number of rotations of the rubbing roller 33, the pressing amount of the rubbing roller 33, etc. can be set as appropriate.

Then, shifting the metal mask 32 in the horizontal direction in FIG. 11 (a), the 12 (a), the second of the second domain _{D 2} metal mask portion corresponding to 32 of the vertical alignment film 30 Align and fix so that the opening of each corresponds. Thus, a portion corresponding to a second domain D ₂ is in a state of being exposed from the metal mask 32, a portion corresponding to the first domain D ₁ is in the state of being covered by the metal mask 32.

Next, as shown in FIG. 12B, the rubbing roller 33 is rotated clockwise on the second vertical alignment film 30 through the metal mask 32, and the second substrate 22 is moved from the right to the left in the drawing. Move in the direction of. Thus, with respect to the second vertical alignment film 30, only the portion corresponding to the second domain D ₂ performs a second rubbing process, the portion corresponding to the first domain D ₁ second rubbing It is possible to prevent processing. Thus, in the present embodiment, the rubbing process is performed twice on the second vertical alignment film 30.

  In the present embodiment, either the first rubbing process or the second rubbing process may be performed first. Alternatively, the rubbing process may be performed twice on the first vertical alignment film 28 and the rubbing process may not be performed on the second vertical alignment film 30.

  Next, the first substrate 21 and the second substrate 22 are bonded together to assemble a liquid crystal cell. At this time, the side where the first vertical alignment film 28 is formed and the side where the second vertical alignment film 30 is formed are overlapped so as to face inward. By sandwiching a spacer (not shown) such as a resin between the first substrate 21 and the second substrate 22, the distance (d) between the substrates can be kept constant.

  Next, liquid crystal molecules 31 having negative dielectric anisotropy are injected and sealed between the first substrate 21 and the second substrate 22. For example, when d = 4 μm and liquid crystal molecules having a refractive index anisotropy (Δn) of 0.0875 are used, the retardation (Δn · d) of the liquid crystal display element is 350 nm.

  Next, the polarizing plates 25 and 26 are installed. Specifically, the liquid crystal cell 24 is sandwiched and pasted so that the polarizing plates 25 and 26 have a crossed Nicols arrangement. At this time, the polarizing axis 25 or the polarizing plate 26 may be pasted so that the absorption axis of the polarizing plate 25 and the operation direction of the liquid crystal molecules when an electric field is applied, that is, the alignment direction of the liquid crystal molecules when a voltage is applied, form an angle of 45 degrees. it can.

  Although not shown in detail, the liquid crystal display element in this embodiment can be a dot matrix display using dynamic drive. In this case, the liquid crystal display element can have a passive matrix structure. That is, it is possible to display a target image by passive driving using an electrode layer without providing a switching element such as a TFT in each pixel portion constituting the image display.

  Moreover, the liquid crystal display element in this Embodiment can also be set as a segment display.

  Furthermore, the liquid crystal display element in the present embodiment may be composed of both a dot matrix display having a passive matrix structure and a segment display.

  According to the present embodiment, as in the first embodiment, a liquid crystal display element having good viewing angle characteristics in any direction can be obtained.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

4 is a partial cross-sectional view of the liquid crystal display element when no voltage is applied in Embodiment 1. FIG. 3 is a partial cross-sectional view of the liquid crystal display element when a voltage is applied in Embodiment 1. FIG. (A) And (b) is a figure explaining the manufacturing method of the liquid crystal display element of Embodiment 1. FIG. (A) And (b) is a figure explaining the manufacturing method of the liquid crystal display element of Embodiment 1. FIG. FIG. 3 is a diagram showing the viewing angle dependence of contrast for the liquid crystal display element of the first embodiment. It is a figure which shows the viewing angle dependence of ON transmittance | permeability about the liquid crystal display element of Embodiment 1. FIG. It is a comparative example of FIG. It is a comparative example of FIG. In Embodiment 2, it is a fragmentary sectional view of the liquid crystal display element at the time of no voltage application. In Embodiment 2, it is a fragmentary sectional view of the liquid crystal display element at the time of voltage application. (A) And (b) is a figure explaining the manufacturing method of the liquid crystal display element of Embodiment 2. FIG. (A) And (b) is a figure explaining the manufacturing method of the liquid crystal display element of Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,21 1st board | substrate 2,22 2nd board | substrate 3,23 Liquid crystal layer 4,24 Liquid crystal cell 5,6,25,26 Polarizing plate 7,27 1st electrode layer 8,28 1st alignment film 9 , 29 Second electrode layer 10, 30 Second alignment film 11, 31 Liquid crystal molecule 12, 14, 32 Metal mask 13, 33 Rubbing roller

Claims (4)

The liquid crystal layer comprising a pair of substrates each having an electrode layer formed on each of the opposing surfaces, and a liquid crystal layer having negative dielectric anisotropy sandwiched between the pair of substrates, the liquid crystal layer being interposed via the electrode layer In the liquid crystal display element that changes the orientation of the liquid crystal by applying a voltage to the substrate and becomes parallel to the substrate, and displays an image on the display unit
The opposing surfaces of the pair of substrates are each provided with an alignment film that is vertically aligned and has been subjected to an alignment process in a predetermined region. The alignment film of one alignment film and the other The regions subjected to the alignment treatment of the alignment film are alternately arranged in one direction without overlapping each other,
The other alignment film located in the region subjected to the alignment treatment of the one alignment film is not subjected to the alignment treatment, and one alignment film located in the region subjected to the alignment treatment of the other alignment film Is a liquid crystal display element that is not subjected to an alignment treatment. The liquid crystal layer comprising a pair of substrates each having an electrode layer formed on each of the opposing surfaces, and a liquid crystal layer having negative dielectric anisotropy sandwiched between the pair of substrates, the liquid crystal layer being interposed via the electrode layer In the liquid crystal display element that changes the orientation of the liquid crystal by applying a voltage to the substrate and becomes parallel to the substrate, and displays an image on the display unit
The opposing surfaces of the pair of substrates are each provided with a vertical alignment film, and one alignment film is subjected to an alignment process in which the alignment directions are alternately reversed with respect to one direction. A liquid crystal display element, wherein the alignment film is not subjected to alignment treatment.   The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a passive matrix type liquid crystal display element.   The liquid crystal molecules in the region subjected to the alignment treatment of the one alignment film are aligned with a pretilt angle of 1 degree or less from the normal direction of the surface of the substrate on which the one alignment film is provided. The liquid crystal display element according to claim 1, wherein the liquid crystal molecules in the region of the alignment film that has not been applied are aligned perpendicular to the surface of the other substrate.

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