Display device

Abstract

To provide a display device with which a reduction in display quality can be suppressed.SOLUTION: According to one embodiment, the display device comprises: a first substrate including a first transparent substrate, and a pixel electrode located in each of a plurality of pixels on the first transparent substrate; a second substrate including a second transparent substrate, a common electrode facing the pixel electrode, and a transparent layer provided between the second transparent substrate and the common electrode; a liquid crystal layer located between the first substrate and the second substrate and including a stripe-shaped polymer and a liquid crystal molecule; and a plurality of light-emitting elements arranged side by side in a first direction. The transparent layer includes a first transparent layer having a plurality of grooves aligned in the first direction and a second transparent layer provided in each of the plurality of grooves. Each of the plurality of grooves has an opening facing the liquid crystal layer and extends in a second direction orthogonal to the first direction, and the second transparent layer has lower refractive index than the second transparent substrate and the first transparent layer.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a display device. [Background technology]

[0002] Various display devices using polymer-dispersed liquid crystals have been proposed, which can switch between a scattering state that scatters incident light and a transparent state that transmits incident light. Display devices using polymer-dispersed liquid crystals sometimes use an edge-light system in which a light-emitting module is located at the edge of the display panel. Because such display devices have high transmittance, they are expected to be used in a variety of fields. However, there is a demand for improvements to be made to the phenomenon in which brightness decreases with increasing distance from the light-emitting module. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-16684 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present embodiment is to provide a display device capable of suppressing degradation in display quality. [Means for solving the problem]

[0005] According to one embodiment, a display device comprises a first substrate having a first transparent substrate and pixel electrodes arranged on the first transparent substrate for each of a plurality of pixels; a second substrate having a second transparent substrate, a common electrode opposite the pixel electrodes, and a transparent layer provided between the second transparent substrate and the common electrode; a liquid crystal layer arranged between the first substrate and the second substrate and containing streaky polymer and liquid crystal molecules; and a plurality of light-emitting elements aligned in a first direction, wherein the transparent layer comprises a first transparent layer having a plurality of grooves aligned in the first direction, and a second transparent layer provided in each of the plurality of grooves, each of the plurality of grooves having an opening facing the liquid crystal layer and extending in a second direction perpendicular to the first direction, and the second transparent layer has a refractive index lower than that of the second transparent substrate and the first transparent layer.

[0006] According to one embodiment, a display device comprises a first substrate having a first transparent substrate and pixel electrodes arranged on the first transparent substrate for each of a plurality of pixels; a second substrate having a second transparent substrate, a common electrode facing the pixel electrodes, and a transparent layer arranged between the second transparent substrate and the common electrode; a liquid crystal layer arranged between the first substrate and the second substrate and containing striated polymer and liquid crystal molecules; and a plurality of light-emitting elements aligned in a first direction, wherein the transparent layer comprises a first transparent layer formed of an inorganic material and having a plurality of grooves aligned in the first direction; and a second transparent layer formed of an organic material and provided in each of the plurality of grooves, wherein each of the plurality of grooves extends in a second direction perpendicular to the first direction, and the second transparent layer has a lower refractive index than the second transparent substrate and the first transparent layer. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing an example of the configuration of a display device DSP according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of the configuration of the display panel PNL shown in FIG. [Figure 3] FIG. 3 is an exploded perspective view showing the main part of the display device DSP shown in FIG. [Figure 4]FIG. 4 is a plan view showing an example of the configuration of the transparent layer TL shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view showing an example of the configuration of the display device DSP of this embodiment. [Figure 6] FIG. 6 is a plan view showing a display panel PNL' of a comparative example. [Figure 7] FIG. 7 is a diagram for explaining an example of a method for manufacturing the second substrate SUB2 shown in FIG. [Figure 8] FIG. 8 is a diagram for explaining an example of a method for manufacturing the second substrate SUB2 shown in FIG. [Figure 9] FIG. 9 is a diagram for explaining an example of a method for manufacturing the second substrate SUB2 shown in FIG. [Figure 10] FIG. 10 is a diagram for explaining an example of a method for manufacturing the second substrate SUB2 shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present embodiment will be described below with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily make while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual embodiment for clarity of explanation, but these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, components that perform the same or similar functions as those described above with reference to the previous drawings are designated by the same reference numerals, and redundant detailed descriptions may be omitted as appropriate.

[0009] FIG. 1 is a plan view showing an example of the configuration of the display device DSP of this embodiment. In one example, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other, but they may intersect at an angle other than 90 degrees. The first direction X and the second direction Y correspond to directions parallel to the main surfaces of the substrates constituting the display device DSP, and the third direction Z corresponds to the thickness direction of the display device DSP. In this specification, the direction from the first substrate SUB1 to the second substrate SUB2 is referred to as the "upper side" (or simply "up"), and the direction from the second substrate SUB2 to the first substrate SUB1 is referred to as the "lower side" (or simply "lower"). When referring to a "second member above the first member" and a "second member below the first member," the second member may be in contact with the first member or may be spaced apart from the first member. Furthermore, the tip of the arrow indicating the third direction Z is assumed to be an observation position for observing the display device DSP, and viewing from this observation position toward the XY plane defined by the first direction X and the second direction Y is referred to as planar viewing.

[0010] In this embodiment, a liquid crystal display device using a polymer dispersed liquid crystal will be described as an example of the display device DSP. The display device DSP includes a display panel PNL, an IC chip 1, and a wiring substrate 2.

[0011] The display panel PNL includes a first substrate SUB1, a second substrate SUB2, a liquid crystal layer LC, and a seal SE. The first substrate SUB1 and the second substrate SUB2 are formed in the shape of flat plates parallel to the XY plane. The first substrate SUB1 and the second substrate SUB2 overlap each other in a planar view. The first substrate SUB1 and the second substrate SUB2 are bonded together with the seal SE.

[0012] The first substrate SUB1 has an edge E1 extending along the first direction X. The second substrate SUB2 has an edge E2 extending along the first direction X. The edge E2 does not overlap the edge E1 in plan view. The first substrate SUB1 has an extending portion Ex extending from the edge E2 in the second direction Y in plan view. The extending portion Ex does not overlap the second substrate SUB2 in plan view.

[0013] The liquid crystal layer LC is held between the first substrate SUB1 and the second substrate SUB2 and sealed with a seal SE. In Fig. 1, the liquid crystal layer LC and the seal SE are indicated by different diagonal lines.

[0014] As schematically shown in an enlarged view in FIG. 1, the liquid crystal layer LC includes a polymer-dispersed liquid crystal including a polymer 51 and liquid crystal molecules 52. In one example, the polymer 51 is a liquid crystal polymer. The polymer 51 is formed in stripes extending along a first direction X. The liquid crystal molecules 52 are dispersed in gaps between the polymer 51 and are oriented with their major axes aligned along the first direction X. Each of the polymer 51 and the liquid crystal molecules 52 has optical anisotropy or refractive index anisotropy. The responsiveness of the polymer 51 to an electric field is lower than that of the liquid crystal molecules 52 to an electric field.

[0015] In one example, the alignment direction of the polymer 51 hardly changes regardless of the presence or absence of an electric field. On the other hand, the alignment direction of the liquid crystal molecules 52 changes in response to an electric field when a high voltage equal to or greater than a threshold value is applied to the liquid crystal layer LC. When no voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 51 and the liquid crystal molecules 52 are parallel to each other, and light incident on the liquid crystal layer LC is transmitted through the liquid crystal layer LC with almost no scattering within the liquid crystal layer LC (transparent state). When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 51 and the liquid crystal molecules 52 intersect with each other, and light incident on the liquid crystal layer LC is scattered within the liquid crystal layer LC (scattered state).

[0016] The display panel PNL includes, in a plan view, a display section DA that displays an image in an area where the first substrate SUB1 and the second substrate SUB2 overlap, and a frame-shaped non-display section NDA that surrounds the display section DA. The seal SE is located in the non-display section NDA. The display section DA includes pixels PX arranged in a matrix in the first direction X and the second direction Y. The display section DA has edges E3 and E4 that extend along the first direction X. The edge E3 is located between the edge E2 and the edge E4 in the second direction Y.

[0017] As shown enlarged in FIG. 1, each pixel PX includes a switching element SW, a pixel electrode PE, a common electrode CE, a liquid crystal layer LC, etc. The switching element SW is formed, for example, by a thin film transistor (TFT) and is electrically connected to a scanning line G and a signal line S. The scanning line G extends in a first direction X and is electrically connected to the switching element SW in each of the pixels PX aligned in the first direction X. The signal line S extends in a second direction Y, intersects with the scanning line G, and is electrically connected to the switching element SW in each of the pixels PX aligned in the second direction Y. The pixel electrode PE is electrically connected to the switching element SW. Each pixel electrode PE faces the common electrode CE, and the liquid crystal layer LC (particularly, liquid crystal molecules 52) is driven by an electric field generated between the pixel electrode PE and the common electrode CE. The capacitance CS is formed, for example, between an electrode having the same potential as the common electrode CE and an electrode having the same potential as the pixel electrode PE.

[0018] The IC chip 1 and the wiring board 2 are each connected to the extension portion Ex. The IC chip 1 has built-in, for example, a display driver that outputs signals necessary for image display. The wiring board 2 is a bendable flexible printed circuit board. The IC chip 1 may be connected to the wiring board 2. The IC chip 1 and the wiring board 2 may read signals from the display panel PNL, but they mainly function as signal sources that supply signals to the display panel PNL.

[0019] Fig. 2 is a cross-sectional view showing an example of the configuration of the display panel PNL shown in Fig. 1. Here, a cross section of the display unit DA in the XZ plane defined by the first direction X and the third direction Z will be described.

[0020] The first substrate SUB1 includes a transparent substrate 10, insulating films 11, 12, and 13, a capacitance electrode 14, metal lines ML, signal lines S, pixel electrodes PE, and an alignment film AL1. The first substrate SUB1 further includes the switching elements SW and scanning lines G shown in FIG. 1. The scanning lines G are disposed, for example, between the transparent substrate 10 and the insulating film 11.

[0021] The transparent substrate 10 has a main surface (lower surface) 10A and a main surface (upper surface) 10B opposite to the main surface 10A. The main surfaces 10A and 10B are surfaces that are approximately parallel to the XY plane. An insulating film 11 covers the main surface 10B. The signal lines S are disposed on the insulating film 11.

[0022] The insulating film 12 covers the signal lines S. Although not described in detail, the insulating film 12 is formed in a lattice shape overlapping the scanning lines G and the signal lines S. The capacitance electrodes 14 are disposed on the insulating film 12. The metal lines ML are disposed on the capacitance electrodes 14. Although not described in detail, the capacitance electrodes 14 and the metal lines ML are formed in a lattice shape overlapping the insulating film 12.

[0023] The insulating film 13 covers the insulating film 11, the capacitance electrode 14, and the metal line ML. The capacitance electrode 14 is provided between the insulating films 12 and 13. The pixel electrode PE is arranged for each pixel PX between the insulating film 13 and the alignment film AL1. The pixel electrode PE is electrically connected to the switching element SW. The pixel electrode PE faces the capacitance electrode 14 via the insulating film 13, forming a capacitance CS for the pixel PX. The alignment film AL1 covers the pixel electrode PE and the insulating film 13. The alignment film AL1 covers the capacitance electrode 14 and the metal line ML that overlap the insulating film 12 between adjacent pixels PX, i.e., in the region where the signal line S, the scanning line G, and the switching element SW are provided.

[0024] The second substrate SUB2 includes a transparent substrate 20, a transparent layer TL, a light-shielding layer BM, a common electrode CE, an alignment film AL2, and spacers PS.

[0025] The transparent substrate 20 has a main surface (lower surface) 20A and a main surface (upper surface) 20B opposite to the main surface 20A. The main surfaces 20A and 20B are surfaces that are approximately parallel to the XY plane. The main surface 20A of the transparent substrate 20 faces the main surface 10B of the transparent substrate 10.

[0026] The transparent layer TL is disposed between the transparent substrate 20 and the common electrode CE. In the illustrated example, the transparent layer TL is formed on the main surface 20A of the transparent substrate 20. The transparent layer TL includes a first transparent layer 41, a second transparent layer 42, and a third transparent layer 43.

[0027] The first transparent layer 41 is disposed between the transparent substrate 20 and the common electrode CE. In the example shown in Fig. 2, the first transparent layer 41 is disposed between the transparent substrate 20 and the third transparent layer 43, and is formed on the main surface 20A of the transparent substrate 20. The first transparent layer 41 has a surface 41A facing the liquid crystal layer LC and a surface 41B in contact with the main surface 20A.

[0028] The first transparent layer 41 has a plurality of grooves 60. The grooves 60 are arranged side by side in the first direction X and extend in the second direction Y. Each of the grooves 60 has an opening AP. The opening AP faces the liquid crystal layer LC. In the example shown in FIG. 2, each of the grooves 60 penetrates the first transparent layer 41 in the third direction Z. That is, at each groove 60, the main surface 20A of the transparent substrate 20 is exposed from the first transparent layer 41. Note that each of the grooves 60 may have a bottom without penetrating the first transparent layer 41 in the third direction Z. In this case, the main surface 20A of the transparent substrate 20 is not exposed at the bottom of the groove 60. In the example shown in FIG. 2, the groove 60 is located directly above the signal line S in the third direction Z and overlaps the signal line S in a planar view. The detailed shape of the groove 60 will be described later.

[0029] The second transparent layer 42 is disposed in each of the plurality of grooves 60, and is disposed between the transparent substrate 20 and the common electrode CE. In the example shown in FIG. 2, the second transparent layer 42 is disposed between the transparent substrate 20 and the third transparent layer 43. The second transparent layers 42 are disposed side by side in the first direction X and extend in the second direction Y. The first transparent layers 41 and the second transparent layers 42 are disposed alternately in the first direction X. The second transparent layers 42 have the same planar shape as the grooves 60. The detailed shape of the second transparent layer 42 will be described later.

[0030] 2, the second transparent layer 42 is in contact with the transparent substrate 20, the first transparent layer 41, and the third transparent layer 43. The second transparent layer 42 has a surface 42A that is in contact with the third transparent layer 43 and faces the liquid crystal layer LC, a surface 42B that is in contact with the major surface 20A, and a side surface 42S that is in contact with the first transparent layer 41. In the example shown in FIG. 2, the side surface 42S extends in the third direction Z, but may extend in a direction different from the third direction Z.

[0031] 2, the second transparent layer 42 is located directly above the signal line S and overlaps the signal line S in a planar view. The second transparent layer 42 is located directly above the light-shielding layer BM and overlaps the light-shielding layer BM in a planar view. The second transparent layer 42 is located directly above the spacer PS and overlaps the spacer PS in a planar view.

[0032] The third transparent layer 43 is disposed between the first transparent layer 41, the second transparent layer 42, and the common electrode CE. The third transparent layer 43 directly covers the surface 41A of the first transparent layer 41 and the surface 42A of the second transparent layer 42. The second transparent layer 42 is in contact with the transparent substrate 20, the first transparent layer 41, and the third transparent layer 43. The third transparent layer 43 makes the surface 41A of the first transparent layer 41 and the surface 42A of the second transparent layer 42 more flat.

[0033] The first transparent layer 41 has a thickness T41 except for the region where the grooves 60 are provided. The second transparent layer 42 has a thickness T42. The thickness T42 of the second transparent layer 42 is, for example, 1 μm or more. The thickness T41 is equal to the thickness T42 and is, for example, 1 μm or more. The third transparent layer 43 has a thickness T43. The thickness T43 is, for example, about 1 μm. Note that the thickness in this specification corresponds to the length along the third direction Z.

[0034] The light-shielding layer BM is provided between the transparent layer TL and the liquid crystal layer LC. In the example shown in Fig. 2, the light-shielding layer BM is provided between the transparent layer TL and the common electrode CE. The light-shielding layer BM is located, for example, directly above the signal line S and directly above the switching element SW and the scanning line G (not shown).

[0035] The common electrode CE is provided between the transparent layer TL and the alignment film AL2. The common electrode CE covers the transparent layer TL and the light-shielding layer BM. In the example shown in FIG. 2, the common electrode CE covers the third transparent layer 43 and the light-shielding layer BM. The common electrode CE is disposed across the plurality of pixels PX and faces each of the pixel electrodes PE in the third direction Z via the liquid crystal layer LC. The common electrode CE is electrically connected to the capacitance electrode 14 and has the same potential as the capacitance electrode 14.

[0036] The spacers PS are disposed on the surface of the common electrode CE facing the liquid crystal layer LC, and pass through the liquid crystal layer LC to contact the alignment film AL1. The spacers PS are located, for example, directly above the signal lines S and directly above the switching elements SW and scanning lines G (not shown).

[0037] The alignment film AL2 covers the common electrode CE. The liquid crystal layer LC is provided between the first substrate SUB1 and the second substrate SUB2, and is in contact with the alignment films AL1 and AL2. Here, attention is focused on the liquid crystal layer LC of one pixel PX1. In a planar view, the liquid crystal layer LC has a region LC1 that does not overlap with the second transparent layer 42, and a region LC2 that overlaps with the second transparent layer 42. The region LC1 has a thickness TLC1. The region LC2 has a thickness TLC2. The thickness TLC1 of the region LC1 is equal to the thickness TLC2 of the region LC2. In one example, the thicknesses TLC1 and TLC2 are approximately 3 μm.

[0038] On the first substrate SUB1, the insulating films 11, 12, and 13, the capacitance electrode 14, the signal line S, the pixel electrode PE, and the alignment film AL1 are located between the main surface 10B and the liquid crystal layer LC. On the second substrate SUB2, the light-shielding layer BM, the common electrode CE, and the alignment film AL2 are located between the transparent layer TL and the liquid crystal layer LC.

[0039] The transparent substrates 10 and 20 are insulating substrates such as glass substrates or plastic substrates. The insulating film 11 is an inorganic insulating film made of silicon oxide, silicon nitride, silicon oxynitride, or the like. The insulating film 12 is an organic insulating film made of, for example, acrylic resin, or the like. The insulating film 13 is an inorganic insulating film made of silicon nitride.

[0040] The capacitance electrode 14, the pixel electrode PE, and the common electrode CE are transparent electrodes formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

[0041] The alignment films AL1 and AL2 are horizontal alignment films having an alignment restriction force substantially parallel to the XY plane. In one example, the alignment films AL1 and AL2 are subjected to an alignment treatment along the first direction X. The alignment treatment may be a rubbing treatment or a photo-alignment treatment.

[0042] The light-shielding layer BM may be a light-absorbing layer made of a light-absorbing material, a light-reflecting layer made of a light-reflective material, an insulating layer made of an inorganic or organic material, or a conductive layer made of a metal material.

[0043] The first transparent layer 41 is an inorganic film made of an inorganic material such as silicon dioxide. The second transparent layer 42 is made of an organic material such as a siloxane-based resin or a fluorine-based resin. The third transparent layer 43 is made of an organic material different from that of the second transparent layer 42. The third transparent layer 43 is an organic insulating film made of an organic material such as an acrylic resin.

[0044] The transparent substrate 10 has a thickness T1, and the transparent substrate 20 has a thickness T2. In the illustrated example, the thickness T1 is equal to the thickness T2.

[0045] The transparent substrate 20, the first transparent layer 41, and the third transparent layer 43 have a refractive index n1. The second transparent layer 42 has a refractive index n2 that is smaller than the refractive index n1. The refractive index n1 is approximately 1.5, and the refractive index n2 is approximately 1.0 to 1.4.

[0046] Fig. 3 is an exploded perspective view showing the main part of the display device DSP shown in Fig. 1. In Fig. 3, the first transparent layer 41, the second transparent layer 42 and the grooves 60 are shown transparently by dotted lines.

[0047] The display device DSP includes a light guide element LG and a light emitting module LM in addition to the display panel PNL. The first substrate SUB1, the second substrate SUB2, and the light guide element LG are arranged in this order along the third direction Z.

[0048] The light emitting module LM includes a plurality of light emitting elements LD, a light guide LB, and a wiring board F.

[0049] The plurality of light-emitting elements LD are arranged at intervals in the first direction X. Each of the plurality of light-emitting elements LD is connected to a wiring substrate F. In the example shown in FIG. 3, each of the plurality of light-emitting elements LD overlaps the extension portion Ex in a planar view. The light-emitting element LD is, for example, a light-emitting diode. Although not described in detail, the light-emitting element LD includes a red light-emitting portion, a green light-emitting portion, and a blue light-emitting portion. Light emitted from the light-emitting element LD travels along the direction of the arrow indicating the second direction Y.

[0050] The light guide LB is formed in a rod shape extending in the first direction X, and is disposed in the second direction Y between the light emitting element LD and the light guide element LG.

[0051] The light guide element LG includes a transparent substrate 30 .

[0052] The transparent substrate 30 has a main surface (lower surface) 30A and a main surface (upper surface) 30B opposite to the main surface 30A. The main surfaces 30A and 30B are surfaces that are approximately parallel to the XY plane. The main surface 30A faces the main surface 20B of the transparent substrate 20.

[0053] The transparent substrate 30 has a side surface 30C. The side surface 30C is a plane substantially parallel to the XZ plane defined by the first direction X and the third direction Z. The side surface 30C is located on the side facing the light-emitting elements LD in a plan view. The side surface 30C faces the plurality of light-emitting elements LD in the second direction Y via the light guide LB.

[0054] The transparent substrate 30 is bonded to the transparent substrate 20. In the example shown in Fig. 3, the side surface 30C is located directly below the edge E2 of the second substrate SUB2, but it may be located directly below the extension Ex or further outward than the edge E1.

[0055] The transparent substrate 30 is an insulating substrate. The transparent substrate 30 is, for example, a glass substrate, but may also be a plastic substrate made of polymethyl methacrylate (PMMA), polycarbonate (PC), or the like. In one example, the transparent substrate 30 is a single substrate rather than a laminate of multiple substrates.

[0056] The transparent substrate 30 has a thickness T3. In one example, the thickness T3 is thicker than the thickness T1 of the transparent substrate 10 and the thickness T2 of the transparent substrate 20. Note that the thickness T3 may be equal to the thicknesses T1 and T2. In one example, the thickness T3 is 200 μm to 2000 μm.

[0057] The refractive index of the transparent substrate 30 is equivalent to the refractive index n1 of the transparent substrate 20, the first transparent layer 41, and the third transparent layer 43, and is higher than the refractive index n2 of the second transparent layer 42. Here, "equivalent" does not necessarily mean that the difference in refractive index is zero, but also means that the difference in refractive index is 0.03 or less.

[0058] In the illustrated example, each of the plurality of grooves 60 and the second transparent layer 42 overlaps the display section DA in plan view.

[0059] Fig. 4 is a plan view showing an example of the configuration of the transparent layer TL shown in Fig. 3. The third transparent layer 43 is omitted in Fig. 4. The groove 60 and the second transparent layer 42 are also shown in Fig. 4 with their widths enlarged in the first direction X. The area overlapping with the display unit DA is indicated by a dotted line in Fig. 4.

[0060] The groove 60 includes a first end 601 facing the light-emitting element LD, a second end 602 opposite the first end 601, a first edge 603, and a second edge 604. The grooves 60 are arranged side by side in the first direction X and extend in the second direction Y. The first ends 601 are arranged on the same straight line along the first direction X. In the example shown in FIG. 4 , each of the first ends 601 overlaps an edge E3 of the display unit DA in a plan view, and each of the second ends 602 overlaps an edge E4 of the display unit DA in a plan view, but this is not limiting. From the perspective of suppressing light leakage between the edge E2 of the second substrate SUB2 and the display unit DA, it is desirable that each of the first ends 601 be close to the light-emitting element LD beyond the display unit DA.

[0061] Each of the first end 601 and the second end 602 has a first width W1 and a second width W2. In this specification, the width corresponds to the length along the first direction X. The first width W1 is larger than the second width W2. In one example, the first width W1 is smaller than the width L of one light-emitting element LD, and one light-emitting element LD is arranged across multiple grooves 60 aligned in the first direction X. Furthermore, the first width W1 is equal to or smaller than the width WP of one pixel electrode PE (or the pitch of the pixel electrodes PE aligned in the first direction X). For all grooves 60, the first width W1 and the second width W2 are approximately the same.

[0062] The first edge 603 and the second edge 604 extend in directions different from the first direction X and the second direction Y between the first end 601 and the second end 602. For example, a direction intersecting the second direction Y at an acute angle in a clockwise direction is defined as direction D1, and a direction intersecting the second direction Y at an acute angle in a counterclockwise direction is defined as direction D2. Note that the angle θ1 between the second direction Y and direction D1 and the angle θ2 between the second direction Y and direction D2 are the same, but this is not limiting, and the angle between the second direction Y and direction D1 and the angle between the second direction Y and direction D2 may be different.

[0063] The first edge 603 extends along direction D1, and the second edge 604 extends along direction D2. Here, the first edge 603 and the second edge 604 both extend linearly, but they may also be formed in curved shapes. The first width W1 and the second width W2 correspond to the distance between the first edge 603 and the second edge 604 in the first direction X.

[0064] The groove 60 having such a shape has a width that gradually decreases at a constant rate or at an arbitrary rate from the first end 601 to the second end 602. The pitch between adjacent grooves 60 is preferably equal to or less than twice the width WP of the pixel electrode PE (or the pitch of the pixel electrodes PE aligned in the first direction X).

[0065] A second transparent layer 42 is formed in each of the multiple grooves 60. The second transparent layer 42 has the same planar shape as the groove 60. That is, the second transparent layer 42 has a first end 421 facing the light-emitting element LD, a second end 422 opposite the first end 421, a first edge 423, and a second edge 424. The second transparent layers 42 are arranged side by side in the first direction X and extend in the second direction Y. The second transparent layer 42 has a width that gradually decreases at a constant rate or an arbitrary rate from the first end 421 to the second end 422.

[0066] The first transparent layer 41 is exposed between adjacent second transparent layers 42. The pixel electrode PE overlaps two adjacent second transparent layers 42 (or grooves 60) in a plan view. The pixel electrode PE overlaps the first transparent layer 41 between the second transparent layers 42.

[0067] In the display unit DA, attention is focused on the pixel electrode PE1 closest to the light-emitting element LD and the pixel electrode PE2 farthest from the light-emitting element LD. The area where the pixel electrode PE1 overlaps with the second transparent layer 42 is larger than the area where the pixel electrode PE2 overlaps with the second transparent layer 42. In other words, the area where the first transparent layer 41 and the pixel electrode PE1 overlap is smaller than the area where the first transparent layer 41 and the pixel electrode PE2 overlap. In this way, the overlapping area between the pixel electrode PE and the second transparent layer 42 is larger in the region close to the light-emitting element LD than in the region away from the light-emitting element LD.

[0068] As will be described later, the area overlapping the second transparent layer 42 corresponds to an area where light from the light-emitting element LD is hardly incident on the display panel PNL, and the area overlapping the first transparent layer 41 corresponds to an area where light from the light-emitting element LD can be incident on the display panel PNL.

[0069] Fig. 5 is a cross-sectional view showing an example of the configuration of the display device DSP shown in Fig. 1. Note that only the main part of the display panel PNL is shown. With reference to Fig. 5, the light emitted from the light emitting element LD will be described. The light emitting element LD emits light L1 toward the side surface 30C of the transparent substrate 30. After transmitting through the light guide LB, the light L1 emitted from the light emitting element LD is refracted at the side surface 30C and enters the transparent substrate 30 and the transparent substrate 20. Of the light L1 that enters the transparent substrate 20, a portion of the light that travels toward the second transparent layer 42 is reflected at the interface between the transparent substrate 20 and the second transparent layer 42 and does not reach the liquid crystal layer LC or the first substrate SUB1. On the other hand, of the light that travels from the transparent substrate 20 toward the second transparent layer 42, light that has an incident angle smaller than the critical angle transmits through the second transparent layer 42 and reaches the liquid crystal layer LC and the first substrate SUB1, as indicated by the dashed line.

[0070] Furthermore, of the light L1 incident on the transparent substrate 30, the light traveling toward the main surface 30B is reflected at the interface between the transparent substrate 30 and the air layer. In this way, most of the light L1 travels inside the transparent substrate 30 and the transparent substrate 20 while being repeatedly reflected near the side surface 30C (or the region where the second transparent layer 42 is present). Of the traveling light L1, the light traveling toward the region where the second transparent layer 42 is not present passes through the first transparent layer 41 and reaches the liquid crystal layer LC and the first substrate SUB1.

[0071] The liquid crystal layer LC of a pixel to which a voltage is applied scatters the light L1. The liquid crystal layer LC of a pixel to which no voltage is applied transmits the light L1. The display device DSP can be observed from the main surface 10A side and also from the main surface 30B side. The background of the display device DSP can be observed through the display device DSP whether the display device DSP is observed from the main surface 10A side or the main surface 30B side.

[0072] According to this embodiment, it is possible to suppress a decrease in the display quality of the display panel PNL. When focusing on the luminance distribution of the light L1 from the light emitting element LD, the luminance tends to decrease in areas farther from the light emitting element LD. One of the causes of this decrease in luminance is the absorption and scattering of undesired light L1 by the liquid crystal layer LC, the signal line S, various insulating films, etc.

[0073] The area where the second transparent layer 42 overlaps the pixel electrode PE corresponds to the area where light L1 from the light-emitting element LD is hardly incident on the display panel PNL, and the area where the second transparent layer 42 does not overlap the pixel electrode PE (or the area between adjacent second transparent layers 42) corresponds to the area where light L1 from the light-emitting element LD is incident on the display panel PNL.

[0074] The overlapping area of ​​the second transparent layer 42 per pixel electrode PE is larger in the region close to the light-emitting element LD than in the region farther from the light-emitting element LD. Therefore, in the region close to the light-emitting element LD, the incidence of light L1 on the display panel PNL is suppressed, and absorption and scattering of light L1 by the liquid crystal layer LC, the signal line S, various insulating films, etc. are suppressed. On the other hand, in the region farther from the light-emitting element LD, the incidence of light L1 on the display panel PNL is promoted. As described above, the light from the light-emitting element LD attenuates with increasing distance from the light-emitting element LD. The overlapping area between the pixel electrode PE1 and the second transparent layer 42 shown in FIG. 4 is larger than the overlapping area between the pixel electrode PE2 and the second transparent layer 42. Therefore, the area where light L1 can enter the pixel electrode PE1 is smaller than the area where light L1 can enter the pixel electrode PE2. Meanwhile, the intensity of light incident on the pixel electrode PE1 is stronger than the intensity of light incident on the pixel electrode PE2. This allows the brightness of the display panel PNL at the pixel electrodes PE1 and PE2 to be equalized.

[0075] The display device DSP scatters light L1 incident on the liquid crystal layer LC by applying an electric field to the liquid crystal layer LC to change the alignment direction of the liquid crystal molecules. If the thickness of the liquid crystal layer LC is non-uniform, the electric field strength applied to the liquid crystal layer LC will be non-uniform, which may impair the display quality of the display panel PNL.

[0076] The second transparent layer 42 has a certain thickness or more to reflect the light L1. When the second transparent layer 42 is provided inside the display panel PNL, the thickness of the second transparent layer 42 may affect the thickness of the liquid crystal layer LC, which may cause the thickness to become non-uniform.

[0077] The second transparent layer 42 is provided in each of the multiple grooves 60 of the first transparent layer 41. This reduces the difference in thickness between the region of the transparent layer TL where the second transparent layer 42 is provided (the region where the incidence of the light L1 on the display panel PNL is suppressed) and the region where the second transparent layer 42 is not provided (the region where the light L1 is incident on the display panel PNL), thereby flattening the alignment film AL2 provided on the transparent layer TL. This makes it possible to uniformize the distance between the alignment film AL1 and the alignment film AL2, i.e., the thickness of the liquid crystal layer LC.

[0078] As described above, according to the present embodiment, it is possible to prevent the brightness of the display panel PNL from becoming non-uniform, and also to prevent the thickness of the liquid crystal layer LC from becoming non-uniform, thereby preventing a decrease in the display quality of the image displayed on the display panel PNL.

[0079] 6 is a cross-sectional view showing a display panel PNL′ of the comparative example. The display panel PNL′ of the comparative example differs from the display panel PNL in that the transparent layer TL includes only the second transparent layer 42 and the third transparent layer 43, and does not include the first transparent layer 41.

[0080] In the comparative example shown in FIG. 6, the second transparent layers 42 are disposed on the main surface 20A of the transparent substrate 20. The second transparent layers 42 are aligned in the first direction X and extend along the second direction Y. The third transparent layer 43 covers the surfaces 42A and side surfaces 42S of the second transparent layers 42 and covers the main surface 20A between adjacent second transparent layers 42. In the transparent layer TL, the region where the second transparent layer 42 is provided protrudes toward the liquid crystal layer LC. That is, in the transparent layer TL, the thickness of the region where the second transparent layer 42 is provided (the region where the incidence of light L1 on the display panel PNL is suppressed) is greater than the thickness of the region where the second transparent layer 42 is not provided (the region where the light L1 is incident on the display panel PNL).

[0081] In the common electrode CE and alignment film AL2 formed on the transparent layer TL having such a cross-sectional shape, the region facing the second transparent layer 42 protrudes further toward the liquid crystal layer LC than the region not facing the second transparent layer 42. As a result, in the liquid crystal layer LC, the thickness TLC2 of the region LC2 facing the second transparent layer 42 is smaller than the thickness TLC1 of the region LC1 not facing the second transparent layer 42, and the thickness of the liquid crystal layer LC becomes non-uniform.

[0082] In a display panel PNL' such as the comparative example shown in FIG. 6, when a voltage is applied to the liquid crystal layer LC, the liquid crystal layer LC has a dense potential distribution in a region LC2 facing the second transparent layer 42, and a sparse potential distribution in a region LC1 not facing the second transparent layer 42. The ratios of the regions LC1 and LC2 differ among pixels aligned in the second direction Y. For example, when the area overlapping with the second transparent layer 42 is relatively large, as in the case of pixel PX1 shown in FIG. 4, the ratio of the region LC2 to the liquid crystal layer LC becomes large. Furthermore, when the area overlapping with the second transparent layer 42 is relatively small, as in the case of pixel PX2 shown in FIG. 4, the ratio of the region LC1 to the liquid crystal layer LC becomes large. Therefore, when the same voltage is applied to pixel PX1 and pixel PX2, the effective electric field strength applied to the liquid crystal layer LC of pixel PX1 differs from the effective electric field strength applied to the liquid crystal layer LC of pixel PX2. As a result, even if light of the same intensity is incident on the pixel PX1 and the pixel PX2, the luminance at the pixel PX1 will be different from the luminance at the pixel PX2, resulting in a deterioration in display quality.

[0083] On the other hand, according to the above embodiment, the thickness of the liquid crystal layer LC is substantially constant regardless of the size of the second transparent layer 42. Therefore, when the same voltage is applied to the pixel PX1 and the pixel PX2, the effective electric field strength applied to the liquid crystal layer LC of the pixel PX1 is substantially the same as the effective electric field strength applied to the liquid crystal layer LC of the pixel PX2. As a result, when light of the same intensity is incident on the pixel PX1 and the pixel PX2, the luminance of the pixel PX1 is substantially the same as the luminance of the pixel PX2, and degradation of display quality can be suppressed.

[0084] Next, a description will be given of a method for manufacturing the second substrate SUB2 shown in Fig. 2. Figs. 7 to 10 are schematic cross-sectional views each showing a part of the manufacturing process for the second substrate SUB2.

[0085] In manufacturing the second substrate SUB2, first, an inorganic film 41a is formed on the transparent substrate 20 by chemical vapor deposition (CVD) (step P1), as shown in the upper part of Fig. 7. In one example, the inorganic film 41a is a silicon dioxide film, and is formed to have a thickness of 1 µm or more.

[0086] After step P1, the inorganic film 41a is patterned. In this patterning, as shown in the middle of FIG. 7, a resist R formed to have a predetermined shape is placed on the inorganic film 41a (step P2). After step P2, as shown in the lower part of FIG. 7, the portions of the inorganic film 41a exposed from the resist R are removed by dry etching using the resist R as a mask (step P3). Specifically, the portions of the inorganic film 41a corresponding to the grooves 60 are removed, and the main surface 20A is exposed.

[0087] After step P3, the resist R is removed (step P4), as shown in the upper part of Fig. 8. This forms the first transparent layer 41 having the grooves 60. After step P4, as shown in the middle part of Fig. 8, an organic material is applied onto the first transparent layer 41 and into the grooves 60, and the organic material is cured by, for example, irradiating it with UV light, to form a resin layer 42a (step P5).

[0088] After step P5, as shown in the lower part of Fig. 8, the resin layer 42a and the first transparent layer 41 are polished to expose the first transparent layer 41, and the second transparent layer 42 is formed (step P6). The polishing is performed by, for example, chemical polishing, mechanical polishing, chemical mechanical polishing (CMP), or the like.

[0089] After step P6, as shown in the upper part of Fig. 9, an organic material is applied onto the first transparent layer 41 and the second transparent layer 42, and the organic material is cured by, for example, irradiating with UV light to form a third transparent layer 43 (step P7). After step P7, as shown in the middle part of Fig. 9, a light-shielding layer BM is formed directly on the second transparent layer 42 (step P8). After step P8, as shown in the lower part of Fig. 9, a common electrode CE is formed on the third transparent layer 43 and the light-shielding layer BM (step P9).

[0090] After step P9, spacers PS are formed directly on the second transparent layer 42 and the light-shielding layer BM (step P10), as shown in the upper part of Fig. 10. After step P10, an alignment film AL2 is formed on the common electrode CE (step P11), as shown in the lower part of Fig. 10. This forms the second substrate SUB2.

[0091] As described above, according to this embodiment, it is possible to provide a display device capable of suppressing degradation in display quality.

[0092] In this embodiment, for example, transparent substrate 10 corresponds to the first transparent substrate, transparent substrate 20 corresponds to the second transparent substrate, transparent substrate 30 corresponds to the third transparent substrate, pixel electrode PE1 corresponds to the first pixel electrode, and pixel electrode PE2 corresponds to the second pixel electrode.

[0093] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims. [Explanation of symbols]

[0094] DSP...Display device PNL...Display panel SE...Seal DA...Display area NDA...Non-display area PX...Pixel LC...liquid crystal layer 51...polymer 52...liquid crystal molecules LG: Light guide element LD: Light emitting element SW: Switching element PE: Pixel electrode CE: Common electrode G...Scanning line S...Signal line 10...Transparent substrate 20...Transparent substrate 30...Transparent substrate TL...Transparent layer 41...First transparent layer 42...Second transparent layer 43...Third transparent layer 60...Groove 601...First end 602...Second end 603...First edge 604...Second edge

Claims

1. a first substrate including a first transparent substrate and pixel electrodes arranged on the first transparent substrate for each of a plurality of pixels; a second substrate including a second transparent substrate, a common electrode facing the pixel electrodes, and a transparent layer provided between the second transparent substrate and the common electrode; a liquid crystal layer disposed between the first substrate and the second substrate and including streaky polymer and liquid crystal molecules; a plurality of light-emitting elements arranged in a first direction, the transparent layer includes a first transparent layer having a plurality of grooves aligned in the first direction, and a second transparent layer provided in each of the plurality of grooves; each of the plurality of grooves has an opening facing the liquid crystal layer and extends in a second direction perpendicular to the first direction; The second transparent layer has a refractive index lower than that of the second transparent substrate and that of the first transparent layer.

2. a first substrate including a first transparent substrate and pixel electrodes arranged on the first transparent substrate for each of a plurality of pixels; a second substrate including a second transparent substrate, a common electrode facing the pixel electrodes, and a transparent layer provided between the second transparent substrate and the common electrode; a liquid crystal layer disposed between the first substrate and the second substrate and including streaky polymer and liquid crystal molecules; a plurality of light-emitting elements arranged in a first direction, the transparent layer includes a first transparent layer having a plurality of grooves aligned in the first direction and formed of an inorganic material, and a second transparent layer provided in each of the plurality of grooves and formed of an organic material, Each of the plurality of grooves extends in a second direction perpendicular to the first direction, The second transparent layer has a refractive index lower than that of the second transparent substrate and that of the first transparent layer.

3. The display device according to claim 1 , wherein the first transparent layer is made of silicon dioxide.

4. The display device according to claim 3 , wherein the first transparent layer has a thickness of 1 μm or more.

5. the transparent layer further includes a third transparent layer covering the first transparent layer and the second transparent layer; 3. The display device according to claim 1, wherein the third transparent layer is made of an organic material different from that of the second transparent layer, and has a refractive index higher than that of the second transparent layer.

6. The display device according to claim 5 , wherein the second transparent layer is in contact with the second transparent substrate, the first transparent layer, and the third transparent layer.

7. Each of the plurality of grooves has a first end portion facing the light emitting element and a second end portion opposite the first end portion, The display device according to claim 1 , wherein the width of the first end portion is greater than the width of the second end portion.

8. the display device further includes a third transparent substrate having a side surface facing the plurality of light-emitting elements; The display device according to claim 1 , wherein the third transparent substrate is bonded to the second transparent substrate.

9. the first substrate includes scanning lines, signal lines intersecting the scanning lines, and switching elements electrically connected to the scanning lines and the signal lines; The display device according to claim 1 , wherein the second transparent layer overlaps the signal line in a plan view.

10. the second substrate further includes a light-shielding layer between the third transparent layer and the common electrode; The display device according to claim 5 , wherein the second transparent layer overlaps the light-shielding layer in a plan view.

11. the second substrate further comprises a spacer; The display device according to claim 1 , wherein the second transparent layer overlaps the spacer in a plan view.

12. The pixel electrodes include a first pixel electrode and a second pixel electrode aligned in the second direction, the first pixel electrode is located between the second pixel electrode and the plurality of light-emitting elements; The display device according to claim 1 , wherein an area where the first pixel electrode overlaps with the second transparent layer is larger than an area where the second pixel electrode overlaps with the second transparent layer.

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