JP2019159209A - Liquid crystal display device - Google Patents

Abstract

To provide a liquid crystal display device which exhibits excellent display characteristics including a gradation reproduction.SOLUTION: A liquid crystal display device displays a display region containing a plurality of pixels; a first substrate; a second substrate; and a liquid crystal layer LC. The first substrate includes: a plurality of signal lines lined in a first direction X; a first electrode EL1 to which a pixel voltage is applied through the signal line arranged in each pixel; and a first orientation film AL1. The second substrate includes a second orientation film AL2 facing the first orientation film AL1. The first substrate has a plurality of first groove structures GS1, which make the first orientation film AL1 sink between pixels adjacent to each other in the first direction X. The first electrode EL1 has a first edge E11 and a second edge E12 in the first direction X. The first edge E11 overlaps with the first groove structure GS1 on the first edge side in a planer view and the second edge E12 is located between the first groove structure GS1 on the second edge side and the first groove structure GS1 on the first edge side in a planer view.SELECTED DRAWING: Figure 7A

Description

  Embodiments described herein relate generally to a liquid crystal display device.

  The liquid crystal display device includes a first substrate, a second substrate, and a liquid crystal layer disposed between the first substrate and the second substrate. Each of the first substrate and the second substrate includes an alignment film in contact with the liquid crystal layer. Further, for example, as disclosed in Patent Document 1, the pixel electrode and the common electrode (counter electrode) are arranged in a dispersed manner on the first substrate and the second substrate, respectively. As another example, both the pixel electrode and the common electrode may be disposed on one of the first substrate and the second substrate.

  The liquid crystal molecules contained in the liquid crystal layer are aligned in the initial alignment direction by the alignment films. When a potential difference is generated between the pixel electrode and the common electrode, the liquid crystal molecules rotate in a direction corresponding to the electric field formed between these electrodes.

  Display characteristics such as pixel gradation reproducibility are affected by the alignment state of liquid crystal molecules in the formation and non-formation of the electric field and the angle at which the pixel is observed. For example, when a display area in which a plurality of pixels are arranged is viewed from the front, the angle at which the left and right pixels (or the upper and lower pixels) of the display area are observed differs. Therefore, when the alignment state of the liquid crystal molecules in each pixel in the display region is uniform, the display characteristics of the left and right pixels (or the upper and lower pixels) may be different.

JP 2011-186285 A

  One of the objects of the present disclosure is to provide a liquid crystal display device excellent in display characteristics such as gradation reproducibility.

  A liquid crystal display device according to an embodiment includes a display region including a plurality of pixels, a first substrate, a second substrate, and a liquid crystal layer. The first substrate includes a plurality of signal lines arranged in a first direction, a first electrode disposed in each of the plurality of pixels, to which a pixel voltage is applied via the signal lines, and a first alignment film. Including. The second substrate includes a second alignment film facing the first alignment film. The liquid crystal layer is disposed between the first alignment film and the second alignment film. The first substrate has a plurality of first groove structures in which the first alignment film is recessed between the pixels adjacent in the first direction. The first electrode has a first edge and a second edge in the first direction. Further, the first edge overlaps with the first groove structure on the first edge side in a plan view, and the second edge is on the first groove structure on the second edge side and the first edge side in a plan view. Located between the first groove structures.

FIG. 1 is a perspective view showing an example of the appearance of the liquid crystal display device according to the first embodiment. FIG. 2 is a perspective view schematically showing an example of a first substrate provided in the liquid crystal display device according to the first embodiment. FIG. 3 is a plan view schematically showing an example of the sub-pixel in the first embodiment. 4 is a schematic cross-sectional view of the display panel taken along line IV-IV in FIG. FIG. 5 is a schematic cross-sectional view of the display panel taken along line VV in FIG. FIG. 6 is a schematic cross-sectional view of the display panel taken along line VI-VI in FIG. FIG. 7A is a cross-sectional view schematically showing an initial alignment state of liquid crystal molecules in the vicinity of the first subpixel in the first embodiment. FIG. 7B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 7A are aligned by the electric field acting on the liquid crystal layer. FIG. 8A is a cross-sectional view schematically showing an initial alignment state of liquid crystal molecules in the vicinity of the second subpixel in the first embodiment. FIG. 8B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 8A are aligned by the electric field acting on the liquid crystal layer. FIG. 9A is a graph showing the viewing angle characteristics of the first subpixel in the first embodiment. FIG. 9B is a graph showing the viewing angle characteristics of the second subpixel in the first embodiment. FIG. 10A is a cross-sectional view schematically showing an initial alignment state of liquid crystal molecules in a display panel according to a second comparative example. 10B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 10A are aligned by an electric field acting on the liquid crystal layer. FIG. 11A is a cross-sectional view schematically showing an initial alignment state of liquid crystal molecules in a display panel according to a third comparative example. FIG. 11B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 11A are aligned by the electric field acting on the liquid crystal layer. FIG. 12A is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the second embodiment. 12B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 12A are aligned by the electric field acting on the liquid crystal layer. FIG. 13A is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the third embodiment. FIG. 13B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 13A are aligned by the electric field acting on the liquid crystal layer. FIG. 14A is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the fourth embodiment. 14B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 14A are aligned by an electric field acting on the liquid crystal layer. FIG. 15A is a schematic cross-sectional view of the first subpixel of the display panel included in the liquid crystal display device according to the fifth embodiment. FIG. 15B is a cross-sectional view schematically showing a state where the liquid crystal molecules shown in FIG. 15A are bend-aligned by the electric field acting on the liquid crystal layer. FIG. 16A is a schematic cross-sectional view of the second subpixel of the display panel included in the liquid crystal display device according to the fifth embodiment. FIG. 16B is a cross-sectional view schematically showing a state in which the liquid crystal molecules shown in FIG. 16A are bend-aligned by the electric field acting on the liquid crystal layer. FIG. 17 is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the sixth embodiment. FIG. 18 is another schematic cross-sectional view of the display panel included in the liquid crystal display device according to the sixth embodiment. FIG. 19 is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the seventh embodiment. FIG. 20 is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the eighth embodiment. FIG. 21 is a schematic cross-sectional view of a display panel included in the liquid crystal display device according to the ninth embodiment.

  Several embodiments will be described with reference to the drawings. It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention are naturally included in the scope of the present invention. In addition, for the sake of clarity, the drawings may be schematically represented with respect to the width, thickness, shape, etc. of each part as compared to actual aspects, but are merely examples, and The interpretation is not limited. In addition, in the present specification and each drawing, components that perform the same or similar functions as those described above with reference to the previous drawings are denoted by the same reference numerals, and repeated detailed description may be omitted as appropriate. .

  In each embodiment, a transmissive liquid crystal display device is disclosed as an example. This liquid crystal display device can be used for various devices such as a virtual reality (VR) viewer, a smartphone, a tablet terminal, a mobile phone terminal, a personal computer, a television receiver, an in-vehicle device, a game machine, and a monitor for a digital camera. it can.

  Each embodiment does not preclude the application of individual technical ideas disclosed in each embodiment to other types of display devices. For example, at least a part of the configuration disclosed in each embodiment can be applied to a reflective liquid crystal display device or the like.

[First Embodiment]
FIG. 1 is a perspective view showing an example of an appearance of a liquid crystal display device DSP (hereinafter referred to as a display device DSP) according to the first embodiment. In the following description, a first direction X, a second direction Y, and a third direction Z are defined as illustrated. The first direction X is a direction in which a plurality of signal lines S described later are arranged. The second direction Y is a direction in which a plurality of scanning lines G described later are arranged. The first direction X, the second direction Y, and the third direction Z are, for example, directions that intersect perpendicularly to each other, but may intersect at an angle other than perpendicular. The direction indicated by the arrow in the third direction Z may be referred to as “up” or “up”, and the opposite direction may be referred to as “down” or “down”.

  The display device DSP includes a display panel PNL, a lighting device BL, and a first polarizing plate PL1. The display panel PNL, the illumination device BL, and the first polarizing plate PL1 are stacked in the third direction Z. A second polarizing plate PL2 described later is disposed between the display panel PNL and the illumination device BL. A phase plate PP, which will be described later, is disposed between the first polarizing plate PL1 and the display panel PNL.

  The display panel PNL includes a first substrate SU1, a second substrate SU2, and a liquid crystal layer (a liquid crystal layer LC described later) disposed between the first substrate SU1 and the second substrate SU2. The first substrate SU1 includes a connection part CN. The connection part CN includes a terminal for connecting a signal supply source such as a flexible circuit board or an IC chip.

  For example, the illumination device BL includes a light guide plate facing the first substrate SU1, a light source such as a plurality of light emitting diodes (LEDs) disposed along an end of the light guide plate, and between the light guide plate and the display panel PNL. And an optical sheet such as a prism sheet or a diffusion sheet. However, the configuration of the illumination device BL is not limited to this example.

  FIG. 2 is a perspective view schematically showing an example of the first substrate SU1. The first substrate SU1 includes a display area DA and a pair of drive circuits PC disposed outside the display area DA. The display area DA includes a large number of pixels PX arranged in the first direction X and the second direction Y. The pixel PX includes a plurality of subpixels SP that display red, green, and blue, for example. The pixel PX may include a sub-pixel SP that displays other colors such as white. The drive circuit PC supplies a signal (scanning signal described later) for driving the subpixel SP. In the present disclosure, the sub-pixel may be simply referred to as a pixel.

  The display area DA includes a first area LDA and a second area RDA arranged in the first direction X. In the illustrated example, the first area LDA is an area on the left side of the center line CL in the first direction X of the display area DA. The second region RDA is a region on the right side of the center line CL. Here, “right” and “left” are merely used for convenience. For example, when the illustrated display area DA is viewed by the user while being rotated by 90 °, the first area LDA is an area above the center line CL when viewed from the user, and the second area RDA is viewed from the user. This is a region below the center line CL. Further, the first region LDA and the second region RDA do not necessarily have to be centered on the center line CL. That is, the width in the first direction X and the height in the second direction Y of the first region LDA and the second region RDA may be different from each other.

  FIG. 3 is a plan view schematically showing an example of the sub-pixel SP. Here, six subpixels SP arranged in the first direction X in the vicinity of the center line CL are shown. In the following description, the subpixel SP in the first area LDA is referred to as a first subpixel SP1, and the subpixel SP in the second area RDA is referred to as a second subpixel SP2. If the two are not particularly distinguished, they may be simply referred to as a subpixel SP.

  The first substrate SU1 includes a plurality of scanning lines G and a plurality of signal lines S. The plurality of scanning lines G extend in the first direction X and are arranged at intervals in the second direction Y. The plurality of signal lines S extend in the second direction Y and are arranged at intervals in the first direction X. In the illustrated example, the center line CL overlaps the central signal line S.

  In the example of this figure, a region defined by two adjacent scanning lines G and two adjacent signal lines S corresponds to the sub-pixel SP. The first substrate SU1 includes a first electrode EL1 (pixel electrode) provided for each subpixel SP, a switching element SW, and a base MB.

  Switching element SW includes a semiconductor layer SC. The semiconductor layer SC can be formed of, for example, polysilicon, but is not limited to this example. The semiconductor layer SC extends while being bent and intersects the scanning line G once. The semiconductor layer SC may intersect the scanning line G twice.

  The pedestal MB overlaps the first electrode EL1 and the semiconductor layer SC in plan view. In the illustrated example, the pedestal MB has a rectangular shape, but is not limited to this example.

  The signal line S is electrically connected to the semiconductor layer SC through the first contact hole CH1. The pedestal MB is electrically connected to the semiconductor layer SC through the second contact hole CH2. The first electrode EL1 is electrically connected to the base MB through the third contact hole CH3.

  A first groove structure GS1 is provided between two first subpixels SP1 adjacent in the first direction X and between two second subpixels SP2 adjacent in the first direction X. For example, the first groove structure GS1 overlaps the signal line S in plan view and extends in the second direction Y along the signal line S. The width of the first groove structure GS1 in the first direction X may be the same as that of the signal line S, may be larger than the signal line S, or may be smaller than the signal line S. Note that the first groove structure GS1 is not provided between the first subpixel SP1 and the second subpixel SP2 that are adjacent to each other via the center line CL. Therefore, in the example of FIG. 3, the first groove structure GS1 overlapping the central signal line S does not exist.

  The first electrode EL1 has a first edge E11 and a second edge E12 in the first direction X. Further, the first electrode EL1 has a third edge E13 and a fourth edge E14 in the second direction Y. In the example of FIG. 3, the first electrode EL1 has a trapezoidal shape in which the width in the second direction Y decreases from the first edge E11 toward the second edge E12. That is, the first edge E11 and the second edge E12 are parallel to the second direction Y, and the third edge E13 and the fourth edge E14 are inclined with respect to both the first direction X and the second direction Y. The shape of the first electrode EL1 is not limited to the example in FIG.

  In the first subpixel SP1, the first edge E11 of the first electrode EL1 overlaps the first groove structure GS1 on the first edge E11 side. On the other hand, the second edge E12 does not overlap with the first groove structure GS1. That is, the second edge E12 is located between the first groove structure GS1 on the second edge E12 side and the first groove structure GS1 on the first edge E11 side.

  The first electrode EL1 of the second subpixel SP2 has a shape symmetrical with respect to the shape of the first electrode EL1 of the first subpixel SP1 and the center line CL. That is, in both the first electrode EL1 disposed in the first subpixel SP1 and the first electrode EL1 disposed in the second subpixel SP2, the second edge E12 is between the center line CL and the first edge E11. Is located. Also for the first electrode EL1 of the second subpixel SP2, the first edge E11 overlaps with the first groove structure GS1, and the second edge E12 does not overlap with the first groove structure GS1.

  In FIG. 3, a plurality of arrows superimposed on the first electrode EL1 indicate the alignment direction of the liquid crystal molecules contained in the liquid crystal layer LC. Details of this will be described later.

  FIG. 4 is a schematic cross-sectional view of the display panel PNL along the line IV-IV in FIG. FIG. 5 is a schematic cross-sectional view of the display panel PNL along the line VV in FIG. 4 and 5 are both structures in the first region LDA.

  As shown in FIGS. 4 and 5, the first substrate SU1 includes a first base material B1, undercoat layers UC1 and UC2, insulating layers IL1 to IL5, a first alignment film AL1, a light shielding layer LS, The semiconductor layer SC, the scanning line G, the signal line S, the first electrode EL1, the second electrode EL2, the pedestal MB, and the metal wiring CM are provided.

  The light shielding layer LS is provided on the upper surface of the first base material B1. The undercoat layer UC1 covers the light shielding layer LS and the upper surface of the first base material B1. The undercoat layer UC2 covers the undercoat layer UC1. The semiconductor layer SC is provided on the undercoat layer UC2 and faces the scanning line G. Further, the region of the semiconductor layer SC that faces the scanning line G faces the light shielding layer LS. The insulating layer IL1 covers the semiconductor layer SC and the undercoat layer UC2. The scanning line G is provided on the insulating layer IL1. The insulating layer IL2 covers the scanning line G and the insulating layer IL1. The insulating layer IL3 covers the insulating layer IL2.

  The signal line S and the base MB are provided on the insulating layer IL3. The insulating layer IL4 covers the signal line S, the pedestal MB, and the insulating layer IL3. The metal wiring CM is provided on the insulating layer IL4 and faces the signal line S. The metal wiring CM extends in the second direction Y so as to overlap with the signal line S in plan view. The second electrode EL2 is provided on the insulating layer IL4 and extends over the plurality of subpixels SP. The metal wiring CM is covered with the second electrode EL2, and is thereby electrically connected to the second electrode EL2. As another example, the metal wiring CM may be provided on the second electrode EL2.

  The insulating layer IL5 covers the second electrode EL2 and the insulating layer IL4. The first electrode EL1 is provided on the insulating layer IL5. The first alignment film AL1 covers the first electrode EL1 and the insulating layer IL5.

  The first contact hole CH1 and the second contact hole CH2 both penetrate the insulating layers IL1 to IL3. The third contact hole CH3 penetrates the insulating layers IL4 and IL5. The signal line S is in contact with the semiconductor layer SC through the first contact hole CH1. The pedestal MB is in contact with the semiconductor layer SC through the second contact hole CH2. The first electrode EL1 is in contact with the pedestal MB through the third contact hole CH3.

  As shown in FIGS. 4 and 5, the second substrate SU2 includes a second base material B2, a black matrix BM (light shielding layer), a color filter layer CF, an overcoat layer OC, a third electrode EL3, And a second alignment film AL2.

  The black matrix BM is provided on the lower surface of the second base material B2, and faces the scanning lines G, signal lines S, and metal wirings CM. The color filter layer CF covers the lower surfaces of the black matrix BM and the second base material B2. The color filter layer CF includes a plurality of color filters of colors corresponding to the subpixels SP. The black matrix BM may be provided below the color filter layer CF. The overcoat layer OC covers the color filter layer CF. The third electrode EL3 covers the overcoat layer OC and extends over the plurality of subpixels SP. The second alignment film AL2 covers the third electrode EL3.

  The liquid crystal layer LC described above is disposed between the first alignment film AL1 and the second alignment film AL2. The first polarizing plate PL1 is disposed above the second base material B2. The second polarizing plate PL2 is disposed below the first base material B1. In the illustrated example, the phase plate PP is disposed between the first polarizing plate PL1 and the second base material B2.

  The first base material B1 and the second base material B2 can be made of, for example, borosilicate glass having a thickness of about 0.2 mm, but may be made of resin such as polyimide. Each of the alignment films AL1 and AL2 is, for example, a polyimide film that has been subjected to photo-alignment treatment, and both align liquid crystal molecules included in the liquid crystal layer LC in the first direction X. The alignment direction of each alignment film AL1, AL2 may be inclined with respect to the first direction X.

  The undercoat layer UC1 is, for example, a silicon oxide film, and the undercoat layer UC2 is, for example, a silicon nitride film. The insulating layers IL1 and IL2 are, for example, silicon oxide films. The insulating layers IL3 and IL5 are, for example, silicon nitride films. The insulating layer IL4 is, for example, a positive organic insulating film. The overcoat layer OC is, for example, a non-photosensitive organic film. Each color filter included in the color filter layer CF is, for example, a negative resist containing a pigment of each color. The black matrix BM is a negative resist containing, for example, a black pigment.

  The first electrode EL1, the second electrode EL2, and the third electrode EL3 can be formed of a transparent conductive material such as ITO (indium tin oxide). The scanning line G and the light shielding layer LS are made of, for example, molybdenum tungsten alloy. The semiconductor layer SC is, for example, polysilicon obtained by polycrystallizing amorphous silicon by laser annealing.

The signal line S and the base MB have a three-layer structure in which, for example, titanium, aluminum, and titanium are sequentially laminated. The metal wiring CM has a three-layer structure in which, for example, a molybdenum tungsten alloy, aluminum, and a molybdenum tungsten alloy are sequentially stacked.
The pedestal MB and the signal line S are both formed of the same metal material and in the same process, and a part of the signal line S in contact with the semiconductor layer SC is used as a source electrode of the switching element SW, and the pedestal MB in contact with the semiconductor layer SC is formed. The drain electrode of the switching element SW can also be used.

  When a scanning signal is supplied to the scanning line G, the signal line S and the first electrode EL1 are conducted through the semiconductor layer SC and the base MB. At this time, the pixel voltage of the signal line S is applied to the first electrode EL1. A common voltage is applied to the second electrode EL2 and the third electrode EL3. Thus, the first electrode EL1 corresponds to a pixel electrode, and the second electrode EL2 and the third electrode EL3 correspond to a common electrode.

  In the present embodiment, the liquid crystal layer LC has a positive dielectric anisotropy, has a high resistance, and exhibits a nematic phase in a wide temperature range including room temperature. The alignment state of the liquid crystal molecules in a state where no potential difference is formed between the first electrode EL1 and each of the electrodes EL2 and EL3 is, for example, homogeneous alignment, and the major axis is parallel to the first direction X in plan view. . Hereinafter, the direction in which the major axis of the liquid crystal molecules faces in a plan view in a state where no potential difference is formed is referred to as an initial alignment direction. A state in which liquid crystal molecules are aligned in the initial alignment direction is referred to as an initial alignment state.

  The absorption axes of the first polarizing plate PL1 and the second polarizing plate PL2 are orthogonal to each other. Furthermore, the absorption axis of the second polarizing plate PL2 forms an angle of 45 ° with respect to the initial alignment direction, for example. For example, the phase plate PP is positive uniaxial, has a retardation of 30 nm, has a slow axis in the plane of the phase plate PP, and is orthogonal to the initial alignment direction.

  In the configuration as described above, an electrically controlled birefringence (ECB) mode display panel PNL can be realized. That is, the subpixel SP is brightly displayed in a state where no potential difference is formed between the first electrode EL1 and each of the electrodes EL2 and EL3, and the subpixel SP is darkly displayed in a state where a potential difference is formed. A white type (normally open type) display panel PNL is obtained. In the vicinity of the interface between the alignment films AL1 and AL2, even if an electric field is applied, the tilt angle of the liquid crystal molecules is difficult to increase, and a residual phase difference can occur. However, since the phase plate PP compensates for the residual phase difference, the transmittance for dark display can be sufficiently reduced even with an applied voltage of about 4 to 5V.

  It should be noted that various modes can be applied to each element without being limited to the materials of the elements of the first substrate SU1 and the second substrate SU2 exemplified above and the configuration of the liquid crystal layer LC.

  As shown in FIG. 5, in the first groove structure GS1, the insulating layer IL4 is provided with a groove GR1. Accordingly, the second electrode EL2, the insulating layer IL5, and the first alignment film AL1 are recessed in the shape of the groove GR1 above the groove GR1. A pair of inclined portions IP1 are formed on the upper surface of the insulating layer IL5. The trench GR1 can be formed by patterning the insulating layer IL4 with a multitone mask, for example. As an example, the trench GR1 has a depth of 1/3 to 1/2 of the thickness of the other part of the insulating layer IL4.

  The first electrode EL1 covers one inclined portion IP1 of the first groove structure GS1 on the left side in the drawing. In the example of FIG. 5, the first edge E11 is located between the pair of inclined portions IP1, but the present invention is not limited to this example. On the other hand, the second edge E12 does not reach the first groove structure GS1 on the right side in the drawing. The second electrode EL2 covers the entire groove GR1. Therefore, the second electrode EL2 overlaps with the first groove structure GS1 in plan view. The metal wiring CM is located at the bottom of the groove GR1. The first alignment film AL1 is formed over the entire first groove structure GS1.

  FIG. 6 is a schematic cross-sectional view of the display panel PNL along the line VI-VI in FIG. In the region where the scanning line G and the signal line S intersect, the first substrate SU1 includes a first spacer SS1, and the second substrate SU2 includes a second spacer SS2. Note that the first spacer SS1 and the second spacer SS2 do not have to be arranged in all the areas where the scanning lines G and the signal lines S intersect in the display area DA.

  The first spacer SS1 extends in the second direction Y along the signal line S, for example. The second spacer SS2 extends in the first direction X along the scanning line G, for example. The first spacer SS1 is covered with the first alignment film AL1. The second spacer SS2 is covered with the second alignment film AL2.

  The first spacer SS1 and the second spacer SS2 are in contact with each other through the alignment films AL1 and AL2 in a plan view. Thereby, the cell gap of the liquid crystal layer LC is secured. Further, even if the substrates SU1 and SU2 are displaced in the first direction X or the second direction Y, the contact of the spacers SS1 and SS2 is maintained.

  The first spacer SS1 is disposed in a region where the insulating layer IL5 is recessed in the first groove structure GS1. For example, the height at which the first spacer SS1 protrudes from the liquid crystal layer LC is smaller than the height at which the second spacer SS2 protrudes from the liquid crystal layer LC. The first substrate SU1 may further include a first spacer SS1 that does not contact the second spacer SS2. In this case, the height at which the first spacer SS1 protrudes from the liquid crystal layer LC may be made larger than the example of FIG.

  FIG. 7A is a cross-sectional view schematically showing an initial alignment state of the liquid crystal molecules LM included in the liquid crystal layer LC in the vicinity of the first subpixel SP1. FIG. 7B is a cross-sectional view schematically showing a state in which the liquid crystal molecules LM shown in FIG. 7A are aligned by the electric field acting on the liquid crystal layer LC.

  In the present embodiment, the first alignment film AL1 and the second alignment film AL2 are both photo-alignment films that have been subjected to photo-alignment processing. Therefore, in the initial alignment state, the tilt angle formed by the major axis of the liquid crystal molecules LM with respect to the microplane of interest in the first alignment film AL1 or the second alignment film AL2 is 0 °. FIG. 7A schematically shows the initial alignment state of the liquid crystal molecules LM existing between the first electrode EL1 and the third electrode EL3. Between the adjacent first groove structures GS1, the major axis of the liquid crystal molecules LM is parallel to the first direction X. In the vicinity of the inclined portion IP1 of the first groove structure GS1, the major axis of the liquid crystal molecule LM is also inclined.

  When a potential difference is generated between the first electrode EL1 and each of the electrodes EL2 and EL3, an electric field as indicated by a broken line is generated. That is, a vertical electric field VE substantially parallel to the third direction Z is generated between the first electrode EL1 and the third electrode EL3. In the vicinity of the first edge E11 and the second edge E12, a parabolic fringe electric field FE is generated between the first electrode EL1 and the second electrode EL2. Further, in the vicinity of these fringe electric fields, the vertical electric field VE is inclined with respect to the third direction Z.

  In the present embodiment, the dielectric anisotropy of the liquid crystal layer LC is positive. Accordingly, the liquid crystal molecules LM rotate in a direction in which the major axis is parallel to the electric field. In the vicinity of the second edge E12, the liquid crystal molecules LM rotate in the first rotation direction R1 indicated by the arrow by the action of the fringe electric field FE and the tilted vertical electric field VE. In the vicinity of the first edge E11, the liquid crystal molecules LM rotate in the first rotation direction R1 due to the action of the vertical electric field VE greatly inclined by the inclined portion IP1. When the liquid crystal molecules LM rotate in the first rotation direction R1 at both ends in this way, the central liquid crystal molecule LM is also affected by these effects and rotates in the first rotation direction R1. As a result, in the first subpixel SP1, the liquid crystal molecules LM rotate in the first rotation direction R1 as a whole. As a result, as shown in FIG. 7B, an alignment state in which each liquid crystal molecule LM is tilted so that the end on the long axis center line CL side (right side in the figure) is positioned higher than the other end is obtained. .

  FIG. 8A is a cross-sectional view schematically showing an initial alignment state of the liquid crystal molecules LM included in the liquid crystal layer LC in the vicinity of the second subpixel SP2. FIG. 8B is a cross-sectional view schematically showing a state in which the liquid crystal molecules LM shown in FIG. 8A are aligned by the electric field acting on the liquid crystal layer LC.

  In the vicinity of the second subpixel SP2, an alignment state symmetric with respect to the vicinity of the first subpixel SP1 and the center line CL is obtained. That is, as shown in FIG. 8A, the liquid crystal molecules LM are rotated in the second rotation direction R2 opposite to the first rotation direction R1 as a whole by the vertical electric field VE and the fringe electric field FE. As a result, as shown in FIG. 8B, an alignment state in which each liquid crystal molecule LM is tilted so that the end on the long axis center line CL side (left side in the figure) is positioned higher than the other end is obtained. .

  In the plan view of FIG. 2, the first sub-pixel SP1 (left end in the figure) and the second sub-pixel SP2 (right end in the figure) in a state where a potential difference is generated between the first electrode EL1 and the electrodes EL2 and EL3. The direction in which the long axis of the liquid crystal molecule LM faces in the vicinity of is indicated by an arrow. The tip side of the arrow corresponds to the end of the long axis located above in the third direction Z.

  In the first subpixel SP1, the middle liquid crystal molecules LM in the second direction Y of the first electrode EL1 are aligned in the first direction X as a whole. In the vicinity of the third edge E13 and the fourth edge E14, the liquid crystal molecules LM are aligned in a direction perpendicular to these edges in plan view. Since the third edge E13 and the fourth edge E14 are inclined with respect to the first direction X and the second direction Y, the liquid crystal molecules LM in the vicinity of these edges are also inclined toward the center line CL. In the second subpixel SP2, the orientation of the liquid crystal molecules LM is symmetric with respect to the first subpixel SP1.

  In the first sub-pixel SP1, the liquid crystal molecules LM are oriented toward the center line CL as a whole, and there are no arrows pointing in opposite directions at least. The same applies to the second subpixel SP2. If there is an arrow pointing in the opposite direction, the force for rotating the liquid crystal molecules LM antagonizes in the intermediate region. Therefore, a domain boundary in which the rotation of the liquid crystal molecules LM is suppressed can occur in the intermediate region. In a normally white display panel, a strip-shaped bright region along a domain boundary is generated in a sub-pixel that is black by voltage application. Thereby, the contrast ratio is lowered. On the other hand, in this embodiment, since no domain boundary occurs in any of the first subpixel SP1 and the second subpixel SP2, a good contrast ratio can be obtained.

  Here, as shown in FIGS. 7B and 8B, a polar angle θ, which is an angle at which the user observes the first subpixel SP1 and the second subpixel SP2, is defined. The polar angle θ here corresponds to an angle at which a straight line connecting the user's viewpoint and the sub-pixel SP is inclined with respect to a perpendicular (third direction Z) of the display panel PNL on the XZ plane. 7B and 8B, the polar angle θ is a positive range on the right side and a negative range on the left side in the figure.

  FIG. 9A is a graph showing the viewing angle characteristics of the first subpixel SP1. FIG. 9B is a graph showing the viewing angle characteristics of the second subpixel SP2. 9A and 9B, the horizontal axis is the polar angle θ, and the vertical axis is the normalized transmittance (0.0 to 1.0) of the first subpixel SP1 or the second subpixel SP2. is there. Curves C1 to C6 in the graph correspond to six gradations having transmittances of 1.0, 0.8, 0.6, 0.4, 0.2, and 0.0, respectively, at θ = 0. In the present embodiment, since the first subpixel SP1 and the second subpixel SP2 have a symmetric structure with respect to the center line CL, the curves C1 to C6 in FIGS. 9A and 9B are symmetric with respect to θ = 0.

  The more uniform the intervals between the curves C1 to C6, the better the gradation reproducibility. As shown in FIG. 9A, in the first subpixel SP1, the curves C1 and C2 intersect at a polar angle θ of about −30 °. That is, in the region where the polar angle θ increases in the negative direction from the intersecting position, the gradations of the curves C1 and C2 are reversed, which is not preferable. On the other hand, the curves C1 to C6 do not intersect in the range where the polar angle θ is positive. Therefore, in the first subpixel SP1, the gradation reproducibility in the range where the polar angle θ is positive is good. This is because when the liquid crystal molecules LM rotate from the initial alignment state of FIG. 7A to the alignment state of FIG. 7B, the change rate of the area of the liquid crystal molecules LM observed from the positive direction of the polar angle θ is observed from the negative direction. This is because the rate of change is greater than

  On the other hand, as shown in FIG. 9B, in the second subpixel SP2, the polar angles θ are about 30 ° and the curves C1 and C2 intersect. On the other hand, in the range where the polar angle θ is negative, the curves C1 to C6 do not intersect. Therefore, the second subpixel SP2 has good gradation reproducibility in the range where the polar angle θ is negative. The reason is the same as in the case of the first subpixel SP1.

  The display panel PNL having the first sub-pixel SP1 and the second sub-pixel SP2 having such viewing angle characteristics has very good display quality when the user's viewpoint is near the center line CL, for example. That is, the first subpixel SP1 in the first area LDA is visually recognized in a range where the polar angle θ is positive, and the second subpixel SP2 in the second area RDA is visually recognized in a range where the polar angle θ is negative. Excellent gradation reproducibility is exhibited in the entire display area DA.

  For example, an electronic device such as a VR viewer includes a pair of display devices for left eye and right eye, and a pair of eyepieces disposed between the display device and the left and right eyes of the user. Both eyes of the user are fixed on the optical axis of each eyepiece. In general, the left end of each display device is observed at a polar angle of 30 °, and the right end is observed at a polar angle of −30 °. According to the graphs of FIGS. 9A and 9B, the gradation reproducibility of the first subpixel SP1 is good when the polar angle θ is in the range of 0 ° to 30 °, and the gradation reproducibility of the second subpixel SP2 is extremely high. The angle θ is good in the range of −30 ° to 0 °. Therefore, when the display device DSP of the present embodiment is applied to each of the above display devices, a VR viewer with extremely high display quality can be realized.

    The mode in which the liquid crystal molecules LM are rotated using the vertical electric field as in the present embodiment uses a horizontal electric field such as an In-Plane Switching (IPS) mode or a kind of such as the Fringe Field Switching (FFS) mode. Excellent response characteristics compared to mode. Therefore, according to the present embodiment, it is possible to obtain a display device DSP that can smoothly switch still images and display moving images.

  For example, in the case of a display device used in a state where the viewpoint and the display area are close like a VR viewer, in order to realize a smooth image display in which individual pixels are not recognized, a definition exceeding 1000 ppi is required. Become. In a mode using a lateral electric field, a complicated electrode shape such as a slit is required in the pixel electrode, and high definition is difficult. On the other hand, in this embodiment, the pixel electrode (first electrode EL1) can have a simple shape, which is advantageous for high definition.

  For example, in a display device using an organic electroluminescence display element (OLED), at least two switching elements are required for a video signal and a power supply for one subpixel. On the other hand, in a liquid crystal display device such as the display device DSP according to the present embodiment, it is only necessary to arrange one switching element SW for one subpixel SP. is there.

A comparative example with the first embodiment will be described below.
[First Comparative Example]
In the first comparative example, it is assumed that the first subpixel SP1 is arranged in the entire display area DA in the structure of the first embodiment. In this comparative example, when the display area DA is viewed from above the center line CL, the gradation characteristics of the first area LDA are good as in the first embodiment, but the gradation characteristics of the second area RDA are good. Is inferior to the first embodiment. That is, the gradation characteristics are different between these areas LDA and RDA, and the luminance is also different. In the second region RDA, there is a possibility that the gradation cannot be sufficiently reproduced. The same problem occurs when the second subpixel SP2 is arranged in the entire display area DA.

[Second Comparative Example]
10A and 10B are schematic cross-sectional views of a display panel XPNL2 according to a second comparative example. In the display panel XPNL2, subpixels SP having the same structure are arranged in both the first area LDA and the second area RDA. FIG. 10A shows the initial alignment state of the liquid crystal molecules LM as in FIG. 7A, and FIG. 10B shows the state where the liquid crystal molecules LM are aligned by an electric field as in FIG. 7B.

  In the display panel XPNL2, the first edge E11 and the second edge E12 of the first electrode EL1 extend to the left and right first groove structures GS1, respectively. In this case, as shown in FIG. 10A, the liquid crystal molecules LM near the first edge E11 rotate in the first rotation direction R1, and the liquid crystal molecules LM near the second edge E12 rotate in the second rotation direction R2. As a result, as shown in FIG. 10B, the tilt angles of the left and right liquid crystal molecules LM are symmetric. In this case, a domain boundary occurs in the vicinity of the center of the first electrode EL1 in the first direction X, so that the contrast ratio of the sub-pixel SP decreases.

[Third comparative example]
11A and 11B are schematic cross-sectional views of a display panel XPNL3 according to a third comparative example. Also in the display panel XPNL3, subpixels SP having the same structure are arranged in both the first area LDA and the second area RDA. 11A shows the initial alignment state of the liquid crystal molecules LM as in FIG. 7A, and FIG. 11B shows the state in which the liquid crystal molecules LM are aligned by an electric field as in FIG. 7B.

  In the display panel XPNL3, neither the first edge E11 nor the second edge E12 of the first electrode EL1 reaches the left and right first groove structures GS1. In this case, as shown in FIG. 11A, the liquid crystal molecules LM near the first edge E11 rotate in the second rotation direction R2, and the liquid crystal molecules LM near the second edge E12 rotate in the first rotation direction R1. As a result, as shown in FIG. 11B, the tilt angles of the left and right liquid crystal molecules LM are symmetric. Also in this case, since the domain boundary is generated near the center in the first direction X of the first electrode EL1, the contrast ratio of the sub-pixel SP is lowered. Furthermore, since the first electrode EL1 is small, the region where the alignment change of the liquid crystal molecules LM occurs is also small. This also reduces the contrast ratio of the sub-pixel SP.

The structure according to the first embodiment is advantageous in terms of gradation characteristics and the like with respect to the above first to third comparative examples due to the various effects described above.
In FIGS. 2 and 3, the first area LDA and the second area RDA are arranged side by side. However, the first area LDA and the second area RDA may be arranged vertically or diagonally as viewed from the user.

[Second Embodiment]
A second embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  12A and 12B are schematic cross-sectional views of the display panel PNL included in the display device DSP according to the present embodiment. FIG. 12A shows the initial alignment state of the liquid crystal molecules LM in the first subpixel SP1 as in FIG. 7A, and FIG. 12B shows the state in which the liquid crystal molecules LM are aligned by an electric field as in FIG. 7B.

  In the present embodiment, instead of the first groove structure GS1, the first substrate SU1 includes a protrusion structure PS that protrudes into the liquid crystal layer LC. The planar shape of the protrusion structure PS and the positional relationship between the protrusion structure PS and the first electrode EL1 in plan view are the same as those of the first groove structure GS1 shown in FIG.

  As shown in FIG. 12A, the protrusion PT is provided in the insulating layer IL4 in the protrusion structure PS. Accordingly, the second electrode EL2, the insulating layer IL5, and the first alignment film AL1 protrude in the shape of the protrusion PT above the protrusion PT. A pair of inclined portions IP are formed on the upper surface of the insulating layer IL5. The protrusion PT can be formed by patterning the insulating layer IL4 with a multitone mask, for example. The protrusion PT may be formed by patterning another insulating layer on the uniform insulating layer IL4.

  The first edge E11 of the first electrode EL1 covers one inclined portion IP of the protruding structure PS on the left side in the drawing. In the illustrated example, the first edge E11 is located between the pair of inclined portions IP, but may be located in the middle of the right inclined portion IP in the drawing. On the other hand, the second edge E12 does not reach the inclined portion IP. The second electrode EL2 covers the entire protrusion PT. The metal wiring CM is located on the top of the protrusion PT. The first alignment film AL1 is formed over the entire protrusion structure PS.

  In the present embodiment, the liquid crystal layer LC has negative dielectric anisotropy. The first alignment film AL1 and the second alignment film AL2 are vertical alignment films that align the liquid crystal molecules LM in the normal direction of these alignment films. In the present embodiment, the display device DSP does not include the phase plate PP. With the above configuration, the sub-pixel SP is darkly displayed when no potential difference is formed between the first electrode EL1 and the electrodes EL2 and EL3, and the sub-pixel SP is brightly displayed when a potential difference is formed. Thus, a normally black type (normally closed type) display panel PNL is obtained.

  In the present embodiment, the tilt angle formed by the long axis of the liquid crystal molecules LM with respect to the microplane of interest in the first alignment film AL1 or the second alignment film AL2 is 90 °. FIG. 12A schematically shows the initial alignment state of the liquid crystal molecules LM existing between the first electrode EL1 and the third electrode EL3. Between the adjacent protrusion structures PS, the major axis of the liquid crystal molecules LM is parallel to the third direction Z. In the vicinity of the inclined portion IP, the major axis of the liquid crystal molecule LM is also inclined.

  In the present embodiment, the dielectric anisotropy of the liquid crystal layer LC is negative. Therefore, the liquid crystal molecules LM rotate in the direction in which the major axis is orthogonal to the electric field. When a potential difference is generated between the first electrode EL1 and each of the electrodes EL2 and EL3, a vertical electric field VE and a fringe electric field FE as indicated by a broken line are generated. In the vicinity of the second edge E12, the liquid crystal molecules LM rotate in the first rotation direction R1 indicated by the arrow by the action of the fringe electric field FE and the tilted vertical electric field VE. In the vicinity of the first edge E11, the liquid crystal molecules LM again rotate in the first rotation direction R1 by the action of the vertical electric field VE greatly inclined by the inclined portion IP. When the liquid crystal molecules LM rotate in the first rotation direction R1 at both ends in this way, the central liquid crystal molecule LM is also affected by these effects and rotates in the first rotation direction R1. As a result, in the first subpixel SP1, the liquid crystal molecules LM rotate in the first rotation direction R1 as a whole. As a result, as shown in FIG. 12B, an alignment state in which each liquid crystal molecule LM is tilted so that the end on the long axis center line CL side (right side in the figure) is positioned below the other end is obtained. .

  The second subpixel SP2 has a symmetrical structure with respect to the first subpixel SP1 and the center line CL shown in FIGS. 12A and 12B. Therefore, in the vicinity of the second subpixel SP2, an alignment state symmetric with respect to the vicinity of the first subpixel SP1 and the center line CL is obtained. From the above, also in the structure of the present embodiment, symmetric viewing angle characteristics can be obtained in the first region LDA and the second region RDA (see FIGS. 2 and 3) as in the first embodiment.

[Third Embodiment]
A third embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  13A and 13B are schematic cross-sectional views of the display panel PNL included in the display device DSP according to the present embodiment. FIG. 13A shows the initial alignment state of the liquid crystal molecules LM in the first subpixel SP1 as in FIG. 7A, and FIG. 13B shows the state in which the liquid crystal molecules LM are aligned by an electric field as in FIG. 7B.

  In the present embodiment, the second alignment film AL2 aligns the liquid crystal molecules LM in the second direction Y. The first alignment film AL1 aligns the liquid crystal molecules LM in the first direction X as in the first embodiment. Further, the liquid crystal layer LC includes a chiral material. As a result, as shown in FIG. 13A, the liquid crystal molecules LM continuously rotate 90 ° between the first alignment film AL1 and the second alignment film AL2.

  In the present embodiment, the display device DSP does not include the phase plate PP. Furthermore, the transmission axis of the first polarizing plate PL1 is parallel to the alignment direction of the second alignment film AL2, and the transmission axis of the second polarizing plate PL2 is parallel to the alignment direction of the first alignment film AL1. With the above structure, a twisted nematic (TN) mode display panel PNL can be realized. That is, the subpixel SP is brightly displayed in a state where no potential difference is formed between the first electrode EL1 and each of the electrodes EL2 and EL3, and the subpixel SP is darkly displayed in a state where a potential difference is formed. A white type (normally open type) display panel PNL is obtained. In the TN mode, the residual phase difference in the vicinity of the first alignment film AL1 and the residual phase difference in the vicinity of the second alignment film AL2 cancel each other, so that even if there is no phase plate PP, an applied voltage of about 4 to 5V is applied. Further, the transmittance in dark display is sufficiently lowered.

  The initial alignment state of the liquid crystal molecules LM in the vicinity of the first alignment film AL1, the vertical electric field VE, and the fringe electric field FE are the same as in the example of FIG. 7A. Accordingly, in the first subpixel SP1, the liquid crystal molecules LM are rotated in the first rotation direction R1 as a whole. As a result, as shown in FIG. 13B, in the vicinity of the first alignment film AL1, each liquid crystal molecule LM is positioned so that the end on the long axis center line CL side (right side in the figure) is positioned higher than the other end. , And an alignment state in which the liquid crystal molecules LM rotate gradually in the XY plane as the second alignment film AL2 is approached.

  The second subpixel SP2 has a symmetrical structure with respect to the first subpixel SP1 and the center line CL shown in FIGS. 13A and 13B. Therefore, in the vicinity of the second subpixel SP2, an alignment state symmetric with respect to the vicinity of the first subpixel SP1 and the center line CL is obtained. From the above, also in the structure of the present embodiment, a symmetric viewing angle characteristic is obtained in the first region LDA and the second region RDA (see FIGS. 2 and 3) as in the first embodiment, and the first The gradation reproducibility is good in both the area LDA and the second area RDA.

[Fourth Embodiment]
The fourth embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  14A and 14B are schematic cross-sectional views of the display panel PNL included in the display device DSP according to this embodiment. 14A shows the initial alignment state of the liquid crystal molecules LM in the first sub-pixel SP1 as in FIG. 7A, and FIG. 14B shows the state in which the liquid crystal molecules LM are aligned by an electric field as in FIG. 7B.

  In the present embodiment, the second alignment film AL2 is a vertical alignment film that aligns the liquid crystal molecules LM in the perpendicular direction of the alignment film. Accordingly, as shown in FIG. 14A, a display panel PNL in a hybrid aligned nematic (HAN) mode in which the tilt angle of the liquid crystal molecules LM continuously increases from the first alignment film AL1 to the second alignment film AL2 can be realized. For example, also in this embodiment, the display panel PNL is a normally white type (normally open type).

  The initial alignment state of the liquid crystal molecules LM in the vicinity of the first alignment film AL1, the vertical electric field VE, and the fringe electric field FE are the same as in the example of FIG. 7A. Accordingly, in the first subpixel SP1, the liquid crystal molecules LM are rotated in the first rotation direction R1 as a whole. Thereby, the alignment state as shown in FIG. 14B is obtained.

  In the initial alignment state, the tilt angle continuously increases counterclockwise in FIG. 14A from the first alignment film AL1 to the second alignment film AL2, and the tilt angle continuously increases clockwise. The parts can be distributed irregularly. However, when the formation of the electric field acting on the liquid crystal layer LC is repeated, the initial alignment of the liquid crystal molecules LM becomes uniform as shown in FIG. 14A.

  The second subpixel SP2 has a symmetrical structure with respect to the first subpixel SP1 and the center line CL shown in FIGS. 14A and 14B. Therefore, in the vicinity of the second subpixel SP2, an alignment state symmetric with respect to the vicinity of the first subpixel SP1 and the center line CL is obtained. From the above, also in the structure of the present embodiment, a symmetric viewing angle characteristic is obtained in the first region LDA and the second region RDA (see FIGS. 2 and 3) as in the first embodiment, and the first The gradation reproducibility is good in both the area LDA and the second area RDA.

[Fifth Embodiment]
The fifth embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  FIG. 15A is a schematic cross-sectional view of the first subpixel SP1 of the display panel PNL included in the display device DSP according to this embodiment. The second substrate SU2 includes an insulating layer IL6 instead of the overcoat layer OC or below the overcoat layer OC. Further, the second substrate SU2 includes a fourth electrode EL4 facing the first electrode EL1, and an insulating layer IL7.

  The third electrode EL3 covers the insulating layer IL6. The insulating layer IL7 covers the third electrode EL3. The fourth electrode EL4 is provided under the insulating layer IL7. The fourth electrode EL4 has, for example, the same planar shape as the first electrode EL1, and is arranged for each subpixel SP (SP1, SP2). The fourth electrodes EL4 adjacent to each other in the first direction X and the second direction Y are electrically connected at a position different from the illustrated cross section, for example. That is, the same voltage is applied to the fourth electrode EL4 disposed in each subpixel SP. The second alignment film AL2 covers the fourth electrode EL4 and the insulating layer IL7. As an example, the insulating layer IL6 is a positive organic insulating film, and the insulating layer IL7 is a silicon nitride film. The fourth electrode EL4 is a transparent conductive film such as ITO.

  In the first subpixel SP1 of the present embodiment, the first edge E11 of the first electrode EL1 is located on the center line CL side (right side in the drawing). The first edge E11 extends to the first groove structure GS1 on the right side in the drawing. On the other hand, the second edge E12 is located between the two first groove structures GS1. That is, in plan view, the first electrode EL1 overlaps with the first groove structure GS1 on the side close to the center line CL (right side in the figure), and the first groove structure GS1 on the side far from the center line CL (left side in the figure). And do not overlap.

  The second substrate SU2 includes a second groove structure GS2 in which the second alignment film AL2 is recessed. The second groove structure GS2 is provided between the sub-pixels SP adjacent to each other in the first direction X, like the first groove structure GS1. In the second groove structure GS2, the insulating layer IL6 is provided with a groove GR2. Accordingly, the third electrode EL3, the insulating layer IL7, and the second alignment film AL2 are recessed in the shape of the groove GR2 below the groove GR2. A pair of inclined portions IP2 are formed on the lower surface of the insulating layer IL7. The depth of the groove GR2 is, for example, the same as that of the groove GR1.

  The fourth electrode EL4 has a first edge E21 and a second edge E22 in the first direction X. The relationship between the two second groove structures GS2 and the edges E21 and E22 is the same as the relationship between the two first groove structures GS1 and the edges E11 and E12.

  In the present embodiment, the retardation of the phase plate PP (see FIG. 4) is, for example, 200 nm. The initial alignment state in the liquid crystal layer LC is homogeneous alignment as in the first embodiment. In this embodiment, this alignment is transformed into a so-called bend alignment to realize an optically compensated birefringence (OCB) mode display panel PNL in which the retardation of the liquid crystal layer LC is compensated by the phase plate PP. Further, by applying an electric field to the liquid crystal layer LC, thereby changing the alignment state so that the tilt angle of the liquid crystal molecules LM in the vicinity of the first alignment film AL1 and the second alignment film AL2 is increased, the normally black type A (normally closed type) display panel PNL is obtained.

  In order to transform the homogeneous alignment into the bend alignment, the first electrode EL1 and the third electrode EL3 are set to the same potential, and the second electrode EL2 and the fourth electrode EL4 are set to the same potential. Thereby, a voltage is applied between the first electrode EL1 and the fourth electrode EL4, between the first electrode EL1 and the second electrode EL2, and between the third electrode EL3 and the fourth electrode EL4. The electric field generated at this time is shown by a broken line in FIG. 15A.

  Since the first electrode EL1 and the fourth electrode EL4 have the same planar shape, the vertical electric field VE between them is basically parallel to the third direction Z. In the vicinity of the first edge E11 and the second edge E12, a fringe electric field FE is generated between the first electrode EL1 and the second electrode EL2. Similarly, a fringe electric field FE is generated between the fourth electrode EL4 and the third electrode EL3 in the vicinity of the first edge E21 and the second edge E22. In a region where the first electrode EL1 and the fourth electrode EL4 overlap with the first groove structure GS1 and the second groove structure GS2, respectively, the vertical electric field VE is bent in an arch shape. Due to the vertical electric field VE and the fringe electric field FE, the liquid crystal molecules LM in the vicinity of the second alignment film AL2 rotate in the first rotation direction R1, and the liquid crystal molecules LM in the vicinity of the first alignment film AL1 rotate in the second rotation direction R2. Rotate to.

  FIG. 15B is a cross-sectional view schematically showing a state where the liquid crystal molecules LM shown in FIG. 15A are bend-aligned by the vertical electric field VE and the fringe electric field FE acting on the liquid crystal layer LC. In the vicinity of the first alignment film AL1, an alignment state in which each liquid crystal molecule LM is tilted so that the end on the long axis center line CL side (right side in the drawing) is positioned below the other end is obtained. On the contrary, in the vicinity of the second alignment film AL2, the alignment state in which each liquid crystal molecule LM is tilted so that the end on the long axis center line CL side (right side in the figure) is located higher than the other end. can get. In the vicinity of the center in the third direction Z of the liquid crystal layer LC, the liquid crystal molecules LM are parallel to the third direction Z.

  FIG. 16A is a cross-sectional view schematically showing the structure of the second subpixel SP2 and the initial alignment state of the liquid crystal molecules LM. FIG. 16B is a cross-sectional view schematically showing a state in which the liquid crystal molecules LM shown in FIG. 16A are aligned by the electric field acting on the liquid crystal layer LC. The second subpixel SP2 has a symmetric structure with respect to the first subpixel SP1 and the center line CL. Thereby, in the second subpixel SP2, a symmetrical alignment state is obtained with respect to the first subpixel SP1 and the center line CL.

  In the state shown in FIG. 15B and FIG. 16B, both the first subpixel SP1 and the second subpixel SP2 are darkly displayed. When making this a bright display, a pixel voltage is applied to the first electrode EL1, and a common voltage is applied to the other electrodes EL2 to EL4. Due to the electric field generated at this time, the tilt angle of the liquid crystal molecules LM is increased, and the liquid crystal molecules LM are in a state close to a vertical alignment parallel to the third direction Z as a whole.

  Also in the structure of the present embodiment described above, symmetric viewing angle characteristics are obtained in the first region LDA and the second region RDA (see FIG. 2 and FIG. 3) as in the first embodiment, and the first region LDA and The gradation reproducibility is good in both of the second regions RDA.

[Sixth Embodiment]
The sixth embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  17 and 18 are schematic cross-sectional views of the display panel PNL included in the display device DSP according to the present embodiment. 17 corresponds to a cross section similar to that of FIG. 4, and FIG. 18 corresponds to a cross section of the first subpixel SP1 similarly to FIG.

  In the present embodiment, the second substrate SU2 does not include the color filter layer CF, and the first substrate SU1 includes the color filter layer CF. The color filter layer CF is disposed between the insulating layer IL3 and the insulating layer IL4 and covers the signal line S. That is, in the present embodiment, the first electrode EL1 and the second electrode EL2 are located between the color filter layer CF and the first alignment film AL1. The color filter layer CF includes color filters respectively corresponding to a plurality of colors. As shown in FIG. 18, the boundary between adjacent color filters coincides with the position of the signal line S.

  As shown in FIG. 17, the color filter layer CF is opened at the position of the third contact hole CH3, and the first electrode EL1 is in contact with the base MB through the opening and the third contact hole CH3. The color filters of each color included in the color filter layer CF have, for example, a stripe shape extending in the second direction Y and arranged in the first direction X. In this case, the opening can be formed between adjacent color filters. The color filters of each color may be in the shape of islands corresponding to the individual sub-pixels SP, and the third contact hole CH3 may be located between these island-shaped color filters.

  In the liquid crystal display device, light emitted from the lighting device and passing through the sub-pixel may not pass through the color filter corresponding to the sub-pixel. Hereinafter, such light is referred to as non-matching light. Since the non-matching light displays a color different from the color that is originally intended to be displayed, it may cause a color mixture of adjacent sub-pixels. In a region observed from a direction inclined with respect to the substrate normal direction, this color mixture is likely to occur.

  For example, in the VR viewer, an eyepiece lens is disposed between the display panel and the user's eyes to widen the viewing angle, and the curvature of the eyepiece lens increases as the required viewing angle increases. In this case, as the region closer to the edge of the visual field is observed, the light that has passed through the display panel from an oblique direction is observed, so that color mixing can occur remarkably. In addition, the higher the definition of the subpixel, the more likely color mixing occurs.

  The display panel PNL in this embodiment is a so-called COA (Color Filter on Array) system in which the color filter layer CF is provided on the first substrate SU1 (array substrate). In the COA method, even if the color filter layer CF and the first electrode EL1 are close to each other or there is an error in bonding between the first substrate SU1 and the second substrate SU2, the position of the color filter layer CF and the subpixel SP is shifted. There is an advantage such as non-matching light. Therefore, color mixing can be suppressed. Furthermore, even when the subpixel SP is made high definition, color mixing is unlikely to occur, so that extremely good display quality can be realized.

  In the present embodiment, the case where the structure of the first embodiment is changed to the COA method is exemplified, but the structure of the other embodiments may be changed to the COA method similarly.

[Seventh Embodiment]
The seventh embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  FIG. 19 is a schematic cross-sectional view of a display panel PNL included in the display device DSP according to the present embodiment. In the present embodiment, the first substrate SU1 includes an insulating layer IL8 disposed between the insulating layer IL4 and the second electrode EL2. The upper surface of the insulating layer IL4 is flat. The insulating layer IL8 is located between the adjacent metal wirings CM in the first direction X. For example, the insulating layer IL8 extends in the second direction Y across the plurality of subpixels SP in plan view. The insulating layer IL8 can be formed, for example, by forming a positive organic insulating film on the insulating layer IL4 and patterning it.

  A first trench structure GS1 is formed by the insulating layer IL8 adjacent to each other through the metal wiring CM. By utilizing the meniscus shape generated when the organic insulating film is fired, the inclined portion IP1 of the first groove structure GS1 can be steeply inclined. In the example of FIG. 19, the first edge E11 of the first electrode EL1 covers the inclined portion IP1, but does not reach the bottom of the first groove structure GS1. As another example, the first edge E11 may cover at least a part of the bottom of the first groove structure GS1.

  The second subpixel SP2 has a symmetrical structure with respect to the first subpixel SP1 and the center line CL shown in FIG. In this embodiment, the first groove structure GS1 is formed by the insulating layer IL8 based on the structure of the first embodiment. However, in the other embodiments, the first groove is similarly formed by the insulating layer IL8. The structure GS1 can be formed. Further, the second groove structure GS2 of the fifth embodiment can be formed of an insulating layer having the same shape as the insulating layer IL8.

[Eighth Embodiment]
The eighth embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  FIG. 20 is a schematic cross-sectional view of a display panel PNL included in the display device DSP according to the present embodiment. In the present embodiment, a slit SL is provided in the second electrode EL2 in the first groove structure GS1. The edge of the second electrode EL2 on the left side in the drawing is located on the right side in the drawing with respect to the first edge E11, for example. Thereby, the fringe electric field FE is suppressed in the vicinity of the first edge E11.

  As in the first embodiment, the fringe electric field FE generated in the vicinity of the first edge E11 may cause the liquid crystal molecules LM to rotate in the direction opposite to the first rotation direction R1. In the present embodiment, since such a fringe electric field FE is suppressed, the liquid crystal molecules LM in the vicinity of the first edge E11 are easily rotated in the first rotation direction R1.

  The second subpixel SP2 has a symmetric structure with respect to the first subpixel SP1 and the center line CL shown in FIG. In this embodiment, the case where the slit SL is provided in the second electrode EL2 is illustrated based on the structure of the first embodiment, but the slit SL may be provided similarly in other embodiments.

[Ninth Embodiment]
The ninth embodiment will be described below. For configurations that are not particularly mentioned, the same configurations as in the first embodiment can be applied.

  FIG. 21 is a schematic cross-sectional view of a display panel PNL included in the display device DSP according to the present embodiment. In the present embodiment, the fifth electrode EL5 is disposed below the first edge E11 of the first electrode EL1. The fifth electrode EL5 is formed in the same layer as the second electrode EL2.

  The fifth electrode EL5 is electrically connected to the first electrode EL1 at a position different from the cross section of FIG. Accordingly, the pixel voltage is applied to the fifth electrode EL5. A common voltage is applied to the second electrode EL2 as in the first embodiment.

  In the structure of the present embodiment, since the first electrode EL1 and the fifth electrode EL5 are at the same potential, the fringe electric field FE does not occur in the vicinity of the first edge E11. Thereby, similarly to the eighth embodiment, the liquid crystal molecules LM in the vicinity of the first edge E11 are easily rotated in the first rotation direction R1.

  The second subpixel SP2 has a symmetric structure with respect to the first subpixel SP1 and the center line CL shown in FIG. In the present embodiment, the case where the fifth electrode EL5 is further provided is illustrated based on the structure of the first embodiment, but the fifth electrode EL5 may be similarly provided in other embodiments.

As described above, all display devices that can be implemented by a person skilled in the art based on the display device described as the embodiment of the present invention are included in the scope of the present invention as long as they include the gist of the present invention.
In the scope of the idea of the present invention, those skilled in the art can conceive various modifications, and these modifications are also considered to be within the scope of the present invention. For example, those in which the person skilled in the art has appropriately added, deleted, or changed the design of the above-described embodiments, or those in which processes have been added, omitted, or changed conditions are also included in the present invention. As long as the gist is provided, it is included in the scope of the present invention.
Further, regarding other operational effects brought about by the aspects described in the respective embodiments, those that are apparent from the description of the present specification or that can be appropriately conceived by those skilled in the art are naturally understood to be brought about by the present invention. Is done.

  DSP ... display device, PNL ... display panel, SU1 ... first substrate, SU2 ... second substrate, LC ... liquid crystal layer, EL1 ... first electrode, EL2 ... second electrode, EL3 ... third electrode, EL4 ... fourth electrode EL5: fifth electrode, S: signal line, G: scanning line, IL1 to IL8: insulating layer, CF: color filter layer, GS1: first groove structure, GS2: second groove structure, LM: liquid crystal molecules.

Claims (11)

A display area including a plurality of pixels;
A first substrate including a plurality of signal lines arranged in a first direction, a first electrode disposed in each of the plurality of pixels, to which a pixel voltage is applied via the signal lines, and a first alignment film;
A second substrate including a second alignment film facing the first alignment film;
A liquid crystal layer disposed between the first alignment film and the second alignment film;
With
The first substrate has a plurality of first groove structures in which the first alignment film is recessed between the pixels adjacent in the first direction,
The first electrode has a first edge and a second edge in the first direction;
The first edge overlaps with the first groove structure on the first edge side in a plan view,
The second edge is located between the first groove structure on the second edge side and the first groove structure on the first edge side in a plan view.
Liquid crystal display device. The display area has a first area and a second area arranged in the first direction,
The plurality of pixels include a first pixel disposed in the first region and a second pixel disposed in the second region,
The first electrode disposed in the first pixel and the first electrode disposed in the second pixel both have the second edge, a boundary between the first region and the second region, and the first electrode Located between one groove structure and the first edge overlapping,
The liquid crystal display device according to claim 1. The first groove structure is not provided between the pixels adjacent to each other across the boundary.
The liquid crystal display device according to claim 2. Each of the first electrode arranged in the first pixel and the first electrode arranged in the second pixel has a width in the second direction that intersects the first direction in the plan view. It has a shape that gets smaller
The liquid crystal display device according to claim 2. The first groove structure overlaps the signal line in plan view;
The liquid crystal display device according to claim 1. The first substrate further includes a second electrode to which a common voltage is applied,
The second electrode overlaps the first groove structure in plan view;
The liquid crystal display device according to claim 1. The first substrate further includes metal wiring that is electrically connected to the second electrode and overlaps the signal line in plan view.
The liquid crystal display device according to claim 6. The second substrate further includes a third electrode to which the common voltage is applied.
The liquid crystal display device according to claim 6 or 7. The first substrate further includes a second electrode to which a common voltage is applied,
The second substrate is
A third electrode to which the common voltage is applied;
A fourth electrode disposed between the third electrode and the second alignment film and facing the first electrode;
The liquid crystal display device according to claim 1. The second substrate has a plurality of second groove structures in which the second alignment film is recessed between the pixels adjacent in the first direction,
The fourth electrode has a first edge and a second edge in the first direction;
The first edge of the fourth electrode overlaps with the second groove structure on the first edge side in plan view,
The second edge of the fourth electrode is located between the second groove structure on the second edge side and the second groove structure on the first edge side in plan view.
The liquid crystal display device according to claim 9. The first substrate further includes a color filter layer corresponding to the color of the pixel,
The first electrode is disposed between the color filter layer and the first alignment film,
The liquid crystal display device according to claim 1.

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