Method of manufacturing display device and display device
The method enhances display quality by controlling light distribution through a transparent and low-refractive index layer configuration, addressing non-uniformity issues in PDLC display devices.
Patent Information
- Application Number
- JP2024116887
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-07-22
- Publication Date
- 2026-02-03
AI Technical Summary
Existing display devices with polymer dispersed liquid crystal (PDLC) layers face issues with deterioration in display quality due to non-uniform light distribution and luminance unevenness.
A manufacturing method that includes forming a transparent layer and a low-refractive index layer on a transparent substrate, where the transparent layer has higher oil repellency than the low-refractive index layer, and the low-refractive index layer has a smaller refractive index than the substrate, to control light distribution and enhance luminance uniformity.
The method effectively suppresses luminance unevenness and maintains display quality by optimizing light incidence, ensuring uniform brightness across the display area.
Smart Images
Figure 2026015948000001_ABST
Abstract
Description
[Technical Field]
[0001] FIELD Embodiments of the present invention relate to a method for manufacturing a display device and a display device. [Background technology]
[0002] In recent years, display devices have been proposed that include a display panel with a polymer dispersed liquid crystal (PDLC) layer, a light source, etc. The polymer dispersed liquid crystal layer can be switched between a scattering state in which it scatters light and a transparent state in which it transmits light.
[0003] In the scattering state, the display device is able to display an image. When the display panel is switched to the transparent state, the user can see through the display panel to see the background. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2019-32411 A [Patent Document 2] JP 2020-16724 A [Patent Document 3] Japanese Patent Application Publication No. 8-31217 [Patent Document 4] International Publication No. 2012 / 020669 Summary of the Invention [Problem to be solved by the invention]
[0005] An object of the present invention is to provide a display device and a manufacturing method thereof that can suppress deterioration in display quality. [Means for solving the problem]
[0006] According to one embodiment, a method for manufacturing a display device includes a liquid crystal layer containing polymer-dispersed liquid crystal, and is capable of switching between a state in which light incident on the liquid crystal layer is transmitted and a state in which the light is scattered, depending on an applied voltage. The method includes disposing a transparent substrate having a first major surface, disposing a transparent material above the first major surface, and patterning the disposed transparent material to form a transparent layer that exposes at least a portion of the first major surface, disposing a low-refractive material on the first major surface and the transparent layer, and patterning the disposed low-refractive material to form a low-refractive layer that exposes the transparent layer. The low-refractive layer has a refractive index lower than that of the transparent substrate. The transparent layer has a higher oil repellency with respect to the low-refractive layer than the first major surface.
[0007] According to another embodiment, a method for manufacturing a display device includes disposing a transparent substrate having a second major surface, forming a common electrode having a third major surface on the second major surface, disposing a transparent material on the third major surface and patterning the disposed transparent material to form a transparent layer exposing at least a portion of the third major surface, disposing a low refractive index material on the third major surface and the transparent layer, and patterning the disposed low refractive index material to form a low refractive index layer exposing the transparent layer. The low refractive index layer has a refractive index lower than that of the transparent substrate. The transparent layer has a higher oil repellency with respect to the low refractive index layer than the third major surface.
[0008] According to a further embodiment, the display device includes a first transparent substrate, a second transparent substrate, a liquid crystal layer including a polymer dispersed liquid crystal disposed between the first transparent substrate and the second transparent substrate, and a low refractive index layer disposed between the liquid crystal layer and the second transparent substrate and having a refractive index smaller than that of the second transparent substrate. The low refractive index layer has a bottom portion located on the second transparent substrate side and an upper portion having a width greater than that of the bottom portion. [Brief explanation of the drawings]
[0009] [Figure 1]FIG. 1 is a diagram showing an example of the configuration of a display device according to the first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the configuration of the display panel shown in FIG. [Figure 3] FIG. 3 is an exploded perspective view showing a main part of the display device according to the first embodiment. [Figure 4] FIG. 4 is a schematic plan view of the display device shown in FIG. [Figure 5] FIG. 5 is a schematic cross-sectional view taken along line VV shown in FIG. [Figure 6] FIG. 6 is a schematic cross-sectional view taken along line VI-VI shown in FIG. [Figure 7] FIG. 7 is a diagram for explaining the method for manufacturing the display device according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining the method for manufacturing the display device according to the first embodiment. [Figure 9] FIG. 9 is a diagram for explaining the method for manufacturing the display device according to the first embodiment. [Figure 10] FIG. 10 is a diagram for explaining the method for manufacturing the display device according to the first embodiment. [Figure 11] FIG. 11 is a diagram for explaining the method for manufacturing the display device according to the first embodiment. [Figure 12] FIG. 12 is a diagram for explaining a method for manufacturing a display device according to a comparative example. [Figure 13] FIG. 13 is a schematic cross-sectional view of a display device according to the second embodiment. [Figure 14] FIG. 14 is a schematic cross-sectional view of a display device according to the third embodiment. [Figure 15] FIG. 15 is a schematic cross-sectional view of a display device according to the third embodiment. [Figure 16] FIG. 16 is a diagram for explaining a method for manufacturing a display device according to the third embodiment. [Figure 17] FIG. 17 is a diagram illustrating a method for manufacturing a display device according to the third embodiment. [Figure 18]FIG. 18 is a diagram illustrating a method for manufacturing a display device according to the third embodiment. [Figure 19] FIG. 19 is a diagram for explaining a method for manufacturing a display device according to the third embodiment. [Figure 20] FIG. 20 is a diagram for explaining a method for manufacturing a display device according to the third embodiment. [Figure 21] FIG. 21 is a schematic cross-sectional view of a display device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION
[0010] Each embodiment will be described below with reference to the drawings. Note that the disclosure is merely an example, and any appropriate modifications that can be easily conceived by a person skilled in the art while maintaining the gist of the invention are naturally included within the scope of the present invention.
[0011] In addition, in order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not 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 given the same reference numerals, and duplicate detailed descriptions may be omitted as appropriate.
[0012] In the drawings, mutually perpendicular X, Y, and Z axes are shown as necessary to facilitate understanding. The direction along the X axis is referred to as the first direction X, the direction along the Y axis is referred to as the second direction Y, and the direction along the Z axis is referred to as the third direction Z. Viewing various elements parallel to the third direction Z is referred to as a planar view.
[0013] In each embodiment, a highly light-transmitting liquid crystal display device (so-called transparent display device) that uses a polymer dispersed liquid crystal is disclosed as an example of a display device, but the configurations disclosed in each embodiment can also be applied to other types of display devices.
[0014] [First embodiment] Fig. 1 is a diagram showing an example of the configuration of a display device DSP according to this embodiment. The display device DSP includes a display panel PNL, a light source unit LU, and a light guide LG. In the example shown in Fig. 1, the light source unit LU and the light guide LG are shown with broken lines to omit parts of them.
[0015] The display panel PNL includes a first substrate SUB1 and a second substrate SUB2 stacked in the third direction Z. In the example shown in Fig. 1, the first substrate SUB1 and the second substrate SUB2 have a rectangular shape in a plan view with long sides parallel to the second direction Y. However, the shapes of the first substrate SUB1 and the second substrate SUB2 are not limited to this example and may be, for example, a rectangular shape with long sides parallel to the first direction X, a circular shape, an elliptical shape, or the like.
[0016] The length of the first substrate SUB1 in the first direction X is greater than the length of the second substrate SUB2 in the first direction X. The first substrate SUB1 has a mounting area MA formed in a portion that protrudes further than the second substrate SUB2 in the direction opposite to the first direction X. The mounting area MA corresponds to the area of the first substrate SUB1 that does not overlap with the second substrate SUB2. An integrated circuit or flexible circuit board (not shown) is mounted in the mounting area MA.
[0017] The display panel PNL has a display area DA for displaying an image and a frame-shaped peripheral area SA surrounding the display area DA. Both the display area DA and the peripheral area SA are formed in the area where the first substrate SUB1 and the second substrate SUB2 overlap. The display area DA has a plurality of pixels PX arranged in a matrix in the first direction X and the second direction Y.
[0018] The display panel PNL further includes a liquid crystal layer LC sealed between the first substrate SUB1 and the second substrate SUB2. As schematically shown in an enlarged view at the bottom of Fig. 1, the liquid crystal layer LC is made of a polymer dispersed liquid crystal containing a polymer 31 and liquid crystal molecules 32.
[0019] In one example, the polymer 31 is a liquid crystal polymer. The polymer 31 is formed in stripes extending along the second direction Y and aligned in the first direction X. The liquid crystal molecules 32 are dispersed in the gaps between the polymer 31 and aligned with their major axes along the second direction Y.
[0020] Each of the polymer 31 and the liquid crystal molecules 32 has optical anisotropy or refractive index anisotropy. The response of the polymer 31 to an electric field is lower than the response of the liquid crystal molecules 32 to an electric field. In one example, the alignment direction of the polymer 31 hardly changes regardless of the presence or absence of an electric field. In contrast, the alignment direction of the liquid crystal molecules 32 changes depending on the voltage applied to the liquid crystal layer LC.
[0021] When no voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 31 and the liquid crystal molecules 32 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).
[0022] When a voltage is applied to the liquid crystal layer LC, the optical axes of the polymer 31 and the liquid crystal molecules 32 intersect with each other, and light incident on the liquid crystal layer LC is scattered within the liquid crystal layer LC (scattering state). That is, the display device DSP can switch between a transparent state and a scattering state depending on the voltage applied.
[0023] As shown enlarged at the top of FIG. 1, a plurality of scanning lines G and a plurality of signal lines S are arranged in the display area DA. The plurality of scanning lines G extend in the second direction Y and are aligned in the first direction X. The plurality of signal lines S extend in the first direction X and are aligned in the second direction Y. The plurality of signal lines S intersect with the plurality of scanning lines G.
[0024] Each pixel PX includes a switching element SW, a pixel electrode PE, a common electrode CE, and a capacitance CS. The switching element SW is formed of, for example, a thin film transistor (TFT), and is electrically connected to a scanning line G and a signal line S. The pixel electrode PE is electrically connected to the switching element SW.
[0025] The liquid crystal layer LC (particularly, the liquid crystal molecules 32) 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.
[0026] The light source unit LU and the light guide LG are arranged along the mounting area MA. The light source unit LU includes a plurality of light emitting elements LS arranged in the second direction Y. Each light emitting element LS irradiates light onto the light guide LG. The light guide LG may be, for example, a lens such as a prism lens.
[0027] For example, the plurality of light-emitting elements LS include a light-emitting element that emits red light, a light-emitting element that emits green light, and a light-emitting element that emits blue light. These light-emitting elements may be aligned in the second direction Y or stacked in the third direction Z. LEDs (Light Emitting Diodes) may be used as the light-emitting elements LS.
[0028] Fig. 2 is a schematic cross-sectional view showing an example of the configuration of the display panel PNL shown in Fig. 1. The first substrate SUB1 includes a transparent substrate 10 (first transparent substrate), insulating films 11 and 12, a capacitance electrode 13, a switching element SW, a pixel electrode PE, and an alignment film AL1.
[0029] Although not shown, the first substrate SUB1 further includes the scanning lines G and signal lines S shown in FIG. 1. The switching elements SW are disposed on the main surface 10B of the transparent substrate 10. The main surface 10B faces the second substrate SUB2. The insulating film 11 covers the switching elements SW. The capacitive electrodes 13 are located between the insulating films 11 and 12.
[0030] In the illustrated example, the insulating film 11 and the capacitance electrode 13 are disposed over the entire surface of each pixel PX, but this is not limiting. The insulating film 11 only needs to be disposed so as to cover at least the switching element SW, the scanning line G, and the signal line S.
[0031] The capacitance electrode 13 may be formed in a grid pattern along the scanning lines G and signal lines S. The pixel electrode PE is arranged for each pixel PX on the insulating film 12. The pixel electrode PE is electrically connected to the switching element SW through an opening OP in the capacitance electrode 13. The pixel electrode PE overlaps the capacitance electrode 13 with the insulating film 12 sandwiched therebetween, forming a capacitance CS for the pixel PX. An alignment film AL1 covers the pixel electrode PE.
[0032] The second substrate SUB2 includes a transparent substrate 20 (third transparent substrate), a light-shielding layer BM, a common electrode CE, and an alignment film AL2. The transparent substrate 20 faces the transparent substrate 10 in the third direction Z. The transparent substrate 20 has a main surface 20A. The main surface 20A faces the transparent substrate 10.
[0033] The light-shielding layer BM and the common electrode CE are disposed on the main surface 20A of the transparent substrate 20. The light-shielding layer BM is located, for example, directly above the switching element SW and directly above the scanning line G and signal line S (not shown).
[0034] The common electrode CE faces the pixel electrode PE in the third direction Z, sandwiching the liquid crystal layer LC. The common electrode CE is disposed across multiple pixels PX and directly covers the light-shielding layer BM. The common electrode CE is electrically connected to the capacitance electrode 13 and is at the same potential as the capacitance electrode 13. An alignment film AL2 covers the common electrode CE.
[0035] The liquid crystal layer LC is located between the transparent substrate 10 and the transparent substrate 20, and is in contact with the alignment films AL1 and AL2. In the first substrate SUB1, the insulating film 11, the insulating film 12, the capacitance electrode 13, the switching element SW, the pixel electrode PE, the alignment film AL1, the scanning line G, and the signal line S are located between the transparent substrate 10 and the liquid crystal layer LC. In the second substrate SUB2, the light-shielding layer BM, the common electrode CE, and the alignment film AL2 are located between the transparent substrate 20 and the liquid crystal layer LC.
[0036] The transparent substrates 10 and 20 are insulating substrates such as glass substrates, plastic substrates, etc. The insulating film 11 is made of a transparent insulating material such as silicon oxide, silicon nitride, silicon oxynitride, or acrylic resin.
[0037] In one example, the insulating film 11 includes an inorganic insulating film and an organic insulating film. The insulating film 12 is an inorganic insulating film such as silicon nitride. The capacitance electrode 13, 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). The light-shielding layer BM is, for example, a conductive layer with lower resistance than the common electrode CE.
[0038] In one example, the light-shielding layer BM is made of an opaque metal material such as molybdenum, aluminum, tungsten, titanium, or silver. 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 second direction Y. The alignment treatment may be a rubbing treatment or a photo-alignment treatment.
[0039] Fig. 3 is an exploded perspective view showing the main parts of the display device DSP according to this embodiment. As shown in Fig. 3, the display device DSP further includes a transparent substrate 30 (second transparent substrate). The transparent substrate 30 is formed in a flat plate shape.
[0040] The transparent substrate 30 is, for example, a glass substrate, but may also be an insulating substrate such as a plastic substrate, etc. The size of the transparent substrate 30 in a plan view is equal to the size of the second substrate SUB2 in a plan view.
[0041] The transparent substrate 30 has a main surface 30A, a main surface 30B opposite to the main surface 30A, and side surfaces 30C and 30D connecting the main surface 30A and the main surface 30B. In this embodiment, the main surface 30A is an example of a first main surface.
[0042] The main surfaces 30A and 30B are parallel to the XY plane defined by the X-axis and Y-axis. The main surface 30A faces the transparent substrate 20 of the second substrate SUB2. The side surfaces 30C and 30D are parallel to the YZ plane defined by the Y-axis and Z-axis. The side surfaces 30C and 30D are arranged in this order in the first direction X.
[0043] The thickness of the transparent substrate 30 is greater than the thicknesses of the first substrate SUB1 and the second substrate SUB2. Here, the thickness is the distance along the third direction Z. In one example, the transparent substrate 30 has a thickness that is at least twice as thick as the first substrate SUB1 and the second substrate SUB2.
[0044] Fig. 4 is a schematic plan view of the display device DSP shown in Fig. 3. Fig. 5 is a schematic cross-sectional view taken along line VV shown in Fig. 4. In each figure, the structure of the display panel PNL and the like is shown schematically, with some elements being omitted.
[0045] As shown in FIG. 5, the liquid crystal layer LC is disposed between the transparent substrate 10 and the transparent substrate 30 of the first substrate SUB1, and the transparent substrate 20 of the second substrate SUB2 is disposed between the liquid crystal layer LC and the transparent substrate 30.
[0046] 4 and 5, the display device DSP further includes a transparent layer 40, a low refractive index layer 50, and a protective layer 60. In Fig. 4, the transparent layer 40 is shaded and the low refractive index layer 50 is dotted. In this embodiment, the transparent substrate 30, the transparent layer 40, the low refractive index layer 50, and the protective layer 60 form a light guide plate for illuminating the display panel PNL.
[0047] The transparent layer 40 has, for example, oil repellency. The transparent layer 40 is formed of, for example, a fluorine-based resin material, a silicon-based resin material, etc. The transparent layer 40 may also be formed of an acrylic resin material, which is a negative-type photosensitive resin, or a phenol-based resin material, which is a positive-type photosensitive resin.
[0048] The transparent layer 40 is disposed on the main surface 30A of the transparent substrate 30, as shown in Fig. 5. The transparent layer 40 overlaps the display area DA. The transparent layer 40 is disposed between the display panel PNL and the transparent substrate 30, as shown in Fig. 5.
[0049] 4, the transparent layer 40 has a plurality of band portions 41. The plurality of band portions 41 extend in a first direction X and are aligned in a second direction Y. Adjacent band portions 41 may be connected to each other or may be separated from each other, for example.
[0050] The multiple band portions 41 each have the same shape. For example, the band portion 41 has a triangular shape in a plan view. The band portion 41 has a first end portion 43 on the side of the side surface 30C, a second end portion 45 opposite the first end portion 43, a first edge 47, and a second edge 49. Here, the end portion includes the end and the area nearby.
[0051] The first edge 47 and the second edge 49 extend in directions different from the first direction X and the second direction Y. For example, a direction intersecting the first direction X at an acute angle counterclockwise is defined as direction D1, and a direction intersecting the first direction X at an acute angle clockwise is defined as direction D2.
[0052] Note that, for example, the angle θ1 between the first direction X and the direction D1 and the angle θ2 between the first direction X and the direction D2 are the same, but this is not limited to this example, and the angle between the first direction X and the direction D1 may be different from the angle between the first direction X and the direction D2.
[0053] The first edge 47 extends along direction D1, and the second edge 49 extends along direction D2. The length of the first edge 47 is, for example, equal to the length of the second edge 49. In the example shown in Fig. 4, both the first edge 47 and the second edge 49 extend linearly, but they may also be formed in curved shapes.
[0054] Thus, the band portion 41 has a width that increases at a constant rate or at an arbitrary rate from the first end 43 to the second end 45 along the first direction X. Here, the width refers to the distance along the second direction Y.
[0055] The width of the first end 43 in the second direction Y is defined as width W1, and the width of the second end 45 in the second direction Y is defined as width W2. In the example shown in FIG. 4, width W1 is smaller than width W2 (W1 <W2)。
[0056] The low refractive index layer 50 is a transparent layer and is formed of an organic material such as a siloxane-based resin. The low refractive index layer 50 is disposed between the liquid crystal layer LC and the transparent substrate 30. Specifically, the low refractive index layer 50 is disposed on the main surface 30A of the transparent substrate 30, as shown in FIG. 5 .
[0057] 4, the low refractive index layer 50 is located inside the outer shape of the transparent substrate 30. The low refractive index layer 50 may be formed to have the same size as the outer shape of the transparent substrate 30.
[0058] 4, the low refractive index layer 50 has a plurality of first portions 51 and a second portion 53. The first portions 51 and the second portions 53 are integrally formed. The first portions 51 overlap the display area DA, and the second portions 53 overlap the peripheral area SA.
[0059] The first portion 51 is disposed between adjacent band portions 41 in the second direction Y. The first portion 51 has, for example, a triangular shape in a plan view. The second portion 53 is formed in a frame shape that surrounds the multiple first portions 51 and the band portions. The portion between the band portions 41 and the second portion 53 is also included in the first portion 51.
[0060] The first portion 51 has a third end 55 between the first ends 43 of adjacent band portions 41 and a fourth end 57 between the second ends 45 of adjacent band portions 41. The third end 55 is connected to, for example, a portion of the second portion 53 on the side surface 30C side, and the fourth end 57 is connected to, for example, a portion of the second portion 53 on the side surface 30D side.
[0061] The first portion 51 has a width that decreases at a constant rate or at an arbitrary rate from the third end 55 to the fourth end 57 along the first direction X. The width of the third end 55 in the second direction Y is defined as width W3, and the width of the fourth end 57 in the second direction Y is defined as width W4. Width W3 is greater than width W4 (W3>W4).
[0062] 5, the low refractive index layer 50 has a thickness greater than that of the band portion 41 of the transparent layer 40. The thickness of the low refractive index layer 50 may be equal to the thickness of the transparent layer 40.
[0063] The protective layer 60 is a transparent layer and may be made of an organic material such as a siloxane-based resin, or an inorganic material such as silicon oxide or silicon nitride.
[0064] 5 , the protective layer 60 covers both the transparent layer 40 and the low refractive index layer 50 from the display panel PNL side. The protective layer 60 surrounds the second portion 53 of the low refractive index layer 50. In other words, the transparent layer 40 and the low refractive index layer 50 are not exposed from the protective layer 60. Therefore, the main surface 30A of the transparent substrate 30 is also not exposed from the protective layer 60.
[0065] The protective layer 60 further has a main surface 60A. The main surface 60A is the surface facing the transparent substrate 20. The protective layer 60 has a function of flattening steps caused by the transparent layer 40 and the low refractive index layer 50. The main surface 60A is, for example, a surface parallel to the XY plane.
[0066] The adhesive layer AD1 bonds the main surface 20B of the transparent substrate 20 and the main surface 60A of the protective layer 60. The adhesive layer AD1 is colorless and transparent, and is formed of, for example, OCA (Optical Clear Adhensive), OCR (Optical Clear Resin), or the like, but is not limited to these examples.
[0067] As shown in Fig. 6, the display panel PNL further includes a seal SE that bonds the first substrate SUB1 and the second substrate SUB2 together. The seal SE surrounds the display area DA in a plan view. The liquid crystal layer LC is sealed in the space surrounded by the seal SE. The second portion 53 of the low refractive index layer 50 overlaps the seal SE in the third direction Z.
[0068] Focusing on the low refractive index layer 50, the display panel PNL, the adhesive layer AD1, the protective layer 60, the low refractive index layer 50, and the transparent substrate 30 are stacked in this order in the third direction Z. Focusing on the transparent layer 40, the display panel PNL, the adhesive layer AD1, the protective layer 60, the transparent layer 40, and the transparent substrate 30 are stacked in this order in the third direction Z.
[0069] The refractive indexes of the transparent substrate 10, the transparent substrate 20, the transparent substrate 30, the transparent layer 40, the protective layer 60, and the adhesive layer AD1 are equivalent. Note that "equivalent" here does not necessarily mean that the difference in refractive index is zero, but also includes cases where the difference in refractive index is 0.05 or less.
[0070] The refractive index of the low refractive index layer 50 is smaller than the refractive index of the transparent substrate 10, the transparent substrate 20, the transparent substrate 30, the transparent layer 40, the protective layer 60, and the adhesive layer AD1. In one example, the refractive index of the transparent substrate 10, the transparent substrate 20, the transparent substrate 30, the transparent layer 40, the protective layer 60, and the adhesive layer AD1 is approximately 1.5, and the refractive index of the adhesive layer AD1 is approximately 1.3 to 1.4.
[0071] The protective layer 60 is made of a material with high transmittance. Here, "high transmittance" means that the transmittance of light in the wavelength range of 400 nm or more and 800 nm or less is 98% or more, for example.
[0072] 5, the light-emitting element LS, the light guide LG, and the transparent substrate 30 are arranged in this order in the first direction X. The light-emitting element LS irradiates light toward the side surface 30C across the light guide LG. Because the light-emitting element LS and the light guide LG do not face the side surface 30C, almost no light emitted from the light-emitting element LS is incident from the side surface 30C.
[0073] Here, the light emitted from the light emitting element LS will be described with reference to Fig. 5. The light emitted from the light emitting element LS is diffused appropriately in the light guide LG and enters the transparent substrate 30 from the side surface 30C.
[0074] The light incident on the transparent substrate 30 from the side surface 30C reaches the liquid crystal layer LC through the transparent substrate 30. As described above, the refractive index of the low refractive index layer 50 is smaller than the refractive index of the transparent substrate 30.
[0075] Therefore, of the light incident on the transparent substrate 30, the light traveling from the transparent substrate 30 toward the first portion 51 of the low refractive index layer 50 is reflected at the interface between the transparent substrate 30 and the first portion 51.
[0076] Furthermore, light traveling toward the main surface 30B is reflected at the interface between the main surface 30B of the transparent substrate 30 and the air layer. In the region where the transparent substrate 30 and the first portion 51 overlap, the light travels inside the transparent substrate 30 while being repeatedly reflected.
[0077] Furthermore, light traveling toward the area where the transparent substrate 30 and the band portion 41 of the transparent layer 40 overlap passes through the transparent substrate 30 and enters the display panel PNL via the band portion 41 and the adhesive layer AD1. Because the refractive index of the transparent layer 40 is equal to that of the transparent substrate 30, almost no light is reflected at the interface between the transparent substrate 30 and the band portion 41.
[0078] In the transparent substrate 30, the side surface 30C corresponds to a region close to the light-emitting element LS, and the side surface 30D corresponds to a region distant from the light-emitting element LS. As described above, the contact area between the main surface 30A of the transparent substrate 30 and the first portion 51 of the low refractive index layer 50 is larger in a region closer to the light-emitting element LS and is smaller in a region farther from the light-emitting element LS.
[0079] The region where the main surface 30A and the first portion 51 overlap corresponds to a region where light incident on the transparent substrate 30 is hardly incident on the display panel PNL side. The region where the main surface 30A and the band portion 41 of the transparent layer 40 overlap corresponds to a region where light incident on the transparent substrate 30 can be incident on the display panel PNL side.
[0080] Light from the light-emitting element LS is likely to attenuate as it moves away from the light-emitting element LS. In this embodiment, the incidence of light from the light-emitting element LS into the display panel PNL is suppressed in areas close to the light-emitting element LS, while the incidence of light into the display panel PNL is promoted in areas farther from the light-emitting element LS. In other words, the light from the light-emitting element LS is delayed by the transparent layer 40 and the first portion 51 of the low-refractive layer 50.
[0081] This makes it possible to make the luminance uniform in the display area DA in the first direction X, thereby suppressing the occurrence of luminance unevenness, and as a result, it becomes possible to suppress a decrease in the display quality of the display device DSP.
[0082] Next, a description will be given of the configuration in the vicinity of the main surface 30A of the transparent substrate 30. Fig. 6 is a schematic cross-sectional view taken along line VI-VI shown in Fig. 4. Fig. 6 shows the transparent substrate 30, the transparent layer 40, the low refractive index layer 50, and the protective layer 60.
[0083] As described above, the strip portions 41 of the transparent layer 40 and the first portions 51 of the low refractive index layer 50 are disposed on the main surface 30A of the transparent substrate 30. The first portions 51 are located between the strip portions 41 that are adjacent to each other.
[0084] 6, a portion of the low refractive index layer 50 overlaps the transparent layer 40. The first portion 51 of the low refractive index layer 50 has a bottom portion 511 located on the transparent substrate 30 side, and an upper portion 513. The bottom portion 511 corresponds to a region overlapping with the band portion 41 in the second direction Y.
[0085] The upper portion 513 has a width greater than that of the bottom portion 511. The upper portion 513 has a portion that protrudes from the side surface of the bottom portion 511. In other words, the band portion 41 has recessed ends on the main surface 30A side of the transparent substrate 30. In the example shown in FIG. 6, the upper portion 513 has a width that decreases in the direction opposite to the third direction Z (the direction away from the main surface 30A). The thickness of the upper portion 513 is greater than that of the bottom portion 511, for example.
[0086] The protective layer 60 covers the transparent layer 40 and the low refractive index layer 50. In other words, the protective layer 60 is in contact with the transparent layer 40 and the low refractive index layer 50. The protective layer 60 has a thick portion 61 that overlaps the band portion 41 of the transparent layer 40. The thick portion 61 has a thickness greater than that of the region of the protective layer 60 that overlaps the low refractive index layer 50.
[0087] Next, an example of a method for manufacturing the display device DSP will be described.
[0088] 7 to 11 are diagrams illustrating a method for manufacturing the display device DSP according to this embodiment, in which the steps are shown in a cross section parallel to an XZ plane defined by a first direction X and a third direction Z.
[0089] First, a display panel PNL including a liquid crystal layer LC and a transparent substrate 30 having a main surface 30A are fabricated. Then, as shown in Fig. 7, the transparent substrate 30 is arranged, and a transparent material 40M is placed above the main surface 30A. In one example, the transparent material 40M is applied directly onto the main surface 30A.
[0090] Next, as shown in Fig. 8, the transparent material 40M is patterned to form the transparent layer 40. The transparent layer 40 has, for example, the shape described with reference to Figs. 4 to 6. At least a portion of the main surface 30A of the transparent substrate 30 is exposed. Specifically, the main surface 30A is exposed between the band portions 41 of adjacent transparent layers 40.
[0091] The transparent layer 40 is formed into a predetermined shape by, for example, an etching process, a photolithography process, or the like. In one example, a resist having a predetermined shape is placed on the transparent material 40M, and the exposed portion of the resist is removed by etching using the resist as a mask. The resist is then removed.
[0092] 9, a low refractive index material 50M is placed on the main surface 30A of the transparent substrate 30 and the transparent layer 40. In one example, the low refractive index material 50M is applied onto the main surface 30A and the transparent layer 40.
[0093] The low refractive index material 50M covers the main surface 30A and the transparent layer 40. The thickness of the low refractive index material 50M is greater than, for example, the thickness of the transparent layer 40. The low refractive index material 50M is in contact with the main surface 30A of the transparent substrate 30 and the transparent layer 40, respectively.
[0094] 10, the low refractive index material 50M is patterned to form the low refractive index layer 50. The low refractive index layer 50 is formed into a predetermined shape by, for example, a photolithography process.
[0095] The low refractive index layer 50 has, for example, the shape described with reference to FIGS. 4 to 6. Most of the low refractive index material 50M is removed (peeled off) in the region that overlaps the transparent layer 40. In other words, the transparent layer 40 is exposed between adjacent first portions 51. The exposed portions correspond to the band portions 41 of the transparent layer 40.
[0096] 11, a protective layer 60 is formed to cover the transparent layer 40 and the low refractive layer 50. This completes the light guide plate. The protective layer 60 and the display panel PNL are then bonded together with an adhesive layer AD1. Through the manufacturing process including the above steps, a display device DSP including the transparent layer 40, the low refractive layer 50, and the protective layer 60 is manufactured.
[0097] 12 is a diagram illustrating a manufacturing method of a display device DSP10 according to a comparative example. The display device DSP10 does not include the transparent layer 40 of the present embodiment. That is, in the manufacturing process of the display device DSP10, the low refractive index material 50M is directly disposed over the entire main surface 30A in the display region DA.
[0098] In such a case, in a region AR between adjacent first portions 51, low refractive index material 50M may remain on main surface 30A as shown in Fig. 12. Hereinafter, the remaining low refractive index material 50M will be referred to as a remainder 50R. When low refractive index material 50M contains a scattering component (for example, a scattering filler), the adhesion to main surface 30A tends to be high, and therefore, remainder 50R is particularly likely to occur.
[0099] Such remaining portions 50R make it difficult to obtain a low refractive index layer 50 having a desired shape. The remaining portions 50R may prevent light from entering the display panel PNL between adjacent first portions 51. This prevents the low refractive index layer 50 from sufficiently forwarding the light, making it difficult to suppress the occurrence of brightness unevenness in the first direction X.
[0100] 10, a transparent layer 40 is formed in advance between adjacent first portions 51. The transparent layer 40 has, for example, a higher oil repellency with respect to the low refractive index layer 50 than the main surface 30A of the transparent substrate 30.
[0101] In other words, the adhesive strength of the disposed low refractive index material 50M to the transparent layer 40 is weaker than the adhesive strength to the main surface 30A. Therefore, in the patterning step (shown in FIG. 10), the low refractive index material 50M disposed on the transparent layer 40 is easier to remove than the low refractive index material 50M in contact with the top of the main surface 30A.
[0102] This allows the low refractive index material 50M to be reliably removed from the desired area, forming a low refractive index layer 50 with the desired shape. This allows the light forwarding effect of the low refractive index layer 50 to be fully achieved, making it possible to appropriately adjust the amount of light incident on the display panel PNL side. As a result, the brightness in the display area DA can be made uniform, and degradation of display quality can be suppressed.
[0103] The shape of the first portion 51 is not limited to the shape in this embodiment and may be another shape. The display device DSP can adjust the amount of light incident on the display panel PNL side by changing, for example, the shape, size, etc. of the first portion 51.
[0104] In the region close to the light emitting element LS, light is not completely blocked from entering the display panel PNL, but light enters the display panel PNL from the transparent layer 40. The side surface 30D is covered with, for example, a reflective material (not shown).
[0105] As a result, the light that reaches the side surface 30D is scattered and reflected by the reflecting material, and travels inside the transparent substrate 30 in the direction opposite to the first direction X. By providing the reflecting material, it is possible to prevent the light from leaking to the outside from the side surface 30D, and by reusing the light, the light utilization efficiency is improved.
[0106] Light incident on the liquid crystal layer LC when no voltage is applied passes through the liquid crystal layer LC with almost no scattering. On the other hand, light incident on the liquid crystal layer LC when a voltage is applied is scattered by the liquid crystal layer LC. In the display device DSP, images can be observed from both the transparent substrate 30 side and the transparent substrate 10 side.
[0107] The display device DSP is a so-called transparent display, and whether the display device DSP is observed from the transparent substrate 30 side or the transparent substrate 10 side, the background of the display device DSP can be observed through the display device DSP.
[0108] The manufacturing method of the display device DSP configured as above and the display device DSP manufactured by this manufacturing method can suppress the degradation of display quality.
[0109] Next, other embodiments will be described. In the configurations of the following embodiments, the same configurations as those of the first embodiment can be applied to parts that are not specifically mentioned.
[0110] [Second embodiment] Fig. 13 is a schematic cross-sectional view of a display device DSP according to this embodiment. This embodiment differs from the first embodiment in that it does not include a transparent layer 40. In this embodiment, after the step of forming a low refractive index layer 50 (shown in Fig. 10), a step of removing the transparent layer 40 is performed, and then a protective layer 60 is formed, as shown in Fig. 13.
[0111] 13, the protective layer 60 covers the low refractive index layer 50 and the main surface 30A of the transparent substrate 30. In other words, the protective layer 60 is in contact with the main surface 30A between the adjacent first portions 51.
[0112] Focusing on the low refractive index layer 50, the low refractive index layer 50 has a bottom portion 511 and an upper portion 513. The bottom portion 511 is located between the protective layers 60 in the second direction Y. From another perspective, a portion of the protective layer 60 is located between the adjacent bottom portions 511.
[0113] The configuration of this embodiment can also achieve the same effects as the first embodiment.
[0114] [Third embodiment] 14 and 15 are schematic cross-sectional views of a display device DSP according to this embodiment. In this embodiment, the transparent layer 40, the low refractive index layer 50, and the protective layer 60 are formed at positions different from those in the first embodiment.
[0115] As shown in Figures 14 and 15, the common electrode CE has a main surface CEF. In this embodiment, the main surface 20A of the transparent substrate 20 is an example of the second main surface, and the main surface CEF is an example of the third main surface. The common electrode CE is disposed on the main surface 20A. The main surface CEF faces the transparent substrate 10.
[0116] The transparent layer 40 and the low refractive index layer 50 are disposed on the main surface CEF of the common electrode CE. In terms of refractive index, the refractive index of the common electrode CE is equivalent to that of the transparent substrate 20, the transparent layer 40, etc. The refractive index of the low refractive index layer 50 is smaller than that of the common electrode CE.
[0117] The transparent layer 40 has, for example, a higher oil repellency with respect to the low refractive index layer 50 than the main surface CEF of the common electrode CE. The transparent layer 40 and the low refractive index layer 50 have, for example, the same shapes as those in the first embodiment.
[0118] 14, the protective layer 60 covers both the transparent layer 40 and the low refractive index layer 50 from the display panel PNL side. The main surface CEF of the common electrode CE is not exposed from the protective layer 60. An alignment film AL2 is located between the protective layer 60 and the liquid crystal layer LC.
[0119] In this embodiment, a transparent layer 40, a low refractive index layer 50, and a protective layer 60 are disposed between the transparent substrate 10 and the transparent substrate 20. An adhesive layer AD2 bonds the main surface 20B of the transparent substrate 20 and the main surface 30A of the transparent substrate 30 together.
[0120] Next, an example of a method for manufacturing the display device DSP will be described. Figures 16 to 20 are diagrams for explaining the method for manufacturing the display device DSP according to this embodiment.
[0121] 16, a transparent substrate 20 having a principal surface 20A is disposed, and a common electrode CE is formed on the principal surface 20A. Next, a transparent material 40M is disposed on the principal surface CEF of the common electrode CE. In one example, the transparent material 40M is applied directly onto the principal surface CEF.
[0122] 17, the transparent material 40M is patterned to form a transparent layer 40. The transparent layer 40 has, for example, the same shape as that of the first embodiment. In this case, at least a portion of the main surface CEF of the common electrode CE is exposed. Specifically, the main surface CEF is exposed between the strip portions 41 of adjacent transparent layers 40.
[0123] 18, a low refractive index material 50M is disposed on the main surface CEF of the common electrode CE and the transparent layer 40. The low refractive index material 50M covers the main surface CEF and the transparent layer 40. The thickness of the low refractive index material 50M is greater than the thickness of the transparent layer 40, for example. The low refractive index material 50M is in contact with the main surface CEF of the common electrode CE and the transparent layer 40, respectively.
[0124] 19, the low refractive index material 50M is patterned to form the low refractive index layer 50. The low refractive index layer 50 has, for example, the same shape as in the first embodiment.
[0125] Most of the low refractive index material 50M is removed (peeled off) in the region that overlaps the transparent layer 40. In other words, the transparent layer 40 is exposed between the adjacent first portions 51. The exposed portions correspond to the band portions 41 of the transparent layer 40.
[0126] The transparent layer 40 has, for example, a higher oil repellency with respect to the low refractive index layer 50 than the main surface CEF of the common electrode CE. In other words, the adhesive strength of the disposed low refractive index material 50M to the transparent layer 40 is smaller than the adhesive strength to the main surface CEF. Therefore, in the patterning step (shown in FIG. 19 ), the low refractive index material 50M disposed on the transparent layer 40 is easier to remove than the low refractive index material 50M in contact with the top of the main surface CEF.
[0127] 20, a protective layer 60 is formed to cover the transparent layer 40 and the low refractive layer 50. Then, an alignment film AL2 is formed on the main surface 60A of the protective layer 60, thereby forming a second substrate SUB2. Through the manufacturing process including the above steps, a display device DSP including the transparent layer 40, the low refractive layer 50, and the protective layer 60 is manufactured.
[0128] The configuration of this embodiment can also achieve the same effects as the first embodiment.
[0129] [Fourth embodiment] Fig. 21 is a schematic cross-sectional view of a display device DSP according to this embodiment. This embodiment differs from the third embodiment in that it does not include a transparent layer 40. In this embodiment, after the step of forming a low refractive index layer 50 (shown in Fig. 19), a step of removing the transparent layer 40 is performed, and then a protective layer 60 is formed, as shown in Fig. 21.
[0130] 21, the protective layer 60 covers the low refractive index layer 50 and the main surface CEF of the common electrode CE. In other words, the protective layer 60 is in contact with the main surface CEF between the adjacent first portions 51.
[0131] Focusing on the low refractive index layer 50, the low refractive index layer 50 has a bottom portion 511 and an upper portion 513. The bottom portion 511 is located between the protective layers 60 in the second direction Y. From another perspective, a portion of the protective layer 60 is located between the adjacent bottom portions 511.
[0132] The configuration of this embodiment can also achieve the same effects as those of the third embodiment. In the third embodiment and this embodiment described above, the positions at which the transparent layer 40 and the low refractive index layer 50 are formed are not limited to the above examples. The transparent layer 40 and the low refractive index layer 50 may be formed on the main surface 20A of the transparent substrate 20. In this case, the common electrode CE is disposed on the protective layer 60 that covers the transparent layer 40 and the low refractive index layer 50.
[0133] In each of the above-described embodiments, a light source unit may be further provided. The light source unit irradiates light toward, for example, the side surface 30D. In such a case, the shapes of the strip portion 41 of the transparent layer 40 and the first portion 51 of the low refractive index layer 50 may also be changed as appropriate.
[0134] The display device DSP may further include a transparent cover member that is overlaid on the transparent substrate 10 from the side opposite to the transparent substrate 30. In other words, the display panel PNL may be sandwiched between the transparent substrate 30 and the cover member. The cover member is an insulating substrate such as a glass substrate or a plastic substrate.
[0135] All manufacturing methods and manufacturing apparatuses that can be implemented by those skilled in the art through appropriate design modifications based on the manufacturing methods and manufacturing apparatuses described above as embodiments of the present invention are within the scope of the present invention as long as they incorporate the gist of the present invention. Within the scope of the concept of the present invention, those skilled in the art will be able to come up with various modifications, and these modifications are also considered to be within the scope of the present invention. For example, those skilled in the art may add or delete components or modify the design of the above-described embodiments, or may add or omit processes or change conditions, as appropriate, and these modifications are also within the scope of the present invention as long as they incorporate the gist of the present invention.
[0136] Furthermore, with regard to other effects brought about by the aspects described in each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be appropriately thought of by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]
[0137] 10, 20, 30...transparent substrate, 40...transparent layer, 41...belt portion, 50...low refractive index layer, 51...first portion, 53...second portion, 60...protective layer, 511...bottom portion, 513...top portion, AD1...adhesive layer, DA...display area, DSP...display device, LC...liquid crystal layer, LU...light source unit, PNL...display panel, PX...pixel, SA...peripheral area, SUB1...first substrate, SUB2...second substrate.
Claims
1. A method for manufacturing a display device having a liquid crystal layer including a polymer dispersed liquid crystal, the display device being capable of switching between a state in which light incident on the liquid crystal layer is transmitted and a state in which the light is scattered in response to an applied voltage, the method comprising: disposing a transparent substrate having a first major surface; a transparent material disposed above the first major surface; patterning the disposed transparent material to form a transparent layer that exposes at least a portion of the first main surface; disposing a low refractive index material on the first major surface and the transparent layer; patterning the deposited low refractive index material to form a low refractive index layer that exposes the transparent layer; the low refractive index layer has a refractive index smaller than that of the transparent substrate; the transparent layer has a higher oil repellency with respect to the low refractive index layer than the first principal surface; A method for manufacturing a display device.
2. A method for manufacturing a display device having a liquid crystal layer including a polymer dispersed liquid crystal, the display device being capable of switching between a state in which light incident on the liquid crystal layer is transmitted and a state in which the light is scattered in response to an applied voltage, the method comprising: disposing a transparent substrate having a second major surface; forming a common electrode having a third major surface on the second major surface; disposing a transparent material on the third major surface; patterning the disposed transparent material to form a transparent layer that exposes at least a portion of the third main surface; disposing a low refractive index material on the third major surface and the transparent layer; patterning the deposited low refractive index material to form a low refractive index layer that exposes the transparent layer; the low refractive index layer has a refractive index smaller than that of the transparent substrate; the transparent layer has a higher oil repellency with respect to the low refractive index layer than the third principal surface; A method for manufacturing a display device.
3. forming a protective layer covering the transparent layer and the low refractive layer; The protective layer has a refractive index equivalent to that of the transparent substrate. The method for manufacturing the display device according to claim 1 or 2.
4. The method further comprises removing the transparent layer after forming the low refractive index layer. The method for manufacturing the display device according to claim 1 .
5. forming a protective layer covering the first major surface and the low refractive index layer; The protective layer has a refractive index equivalent to that of the transparent substrate. The method for manufacturing a display device according to claim 4 .
6. The method further comprises removing the transparent layer after forming the low refractive index layer. The method for manufacturing a display device according to claim 2 .
7. forming a protective layer covering the third major surface and the low refractive index layer; The protective layer has a refractive index equivalent to that of the transparent substrate. The method for manufacturing a display device according to claim 6 .
8. The thickness of the low refractive index layer is greater than the thickness of the transparent layer. The method for manufacturing the display device according to claim 1 or 2.
9. a first transparent substrate; a second transparent substrate; a liquid crystal layer including a polymer dispersed liquid crystal disposed between the first transparent substrate and the second transparent substrate; a low refractive index layer disposed between the liquid crystal layer and the second transparent substrate and having a refractive index smaller than that of the second transparent substrate; The low refractive index layer has a bottom portion located on the second transparent substrate side and an upper portion having a width greater than that of the bottom portion. Display device.
10. a third transparent substrate disposed between the liquid crystal layer and the second transparent substrate; the second transparent substrate has a first main surface facing the third transparent substrate; the low refractive index layer is disposed on the first major surface; The display device according to claim 9 .
11. a transparent layer disposed on the first main surface and having a refractive index equivalent to that of the third transparent substrate; the transparent layer has a plurality of strips extending in a first direction and arranged in a second direction perpendicular to the first direction; the low refractive layer has a portion disposed between the band portions adjacent to each other in the second direction, the transparent layer has a higher oil repellency with respect to the low refractive index layer than the first principal surface; The display device according to claim 10.
12. a third transparent substrate disposed between the liquid crystal layer and the second transparent substrate and having a second main surface facing the first transparent substrate; a common electrode disposed on the second main surface, the common electrode has a third main surface facing the first transparent substrate; the low refractive index layer is disposed on the third major surface; The display device according to claim 9 .
13. a transparent layer disposed on the third main surface and having a refractive index equivalent to that of the third transparent substrate and the common electrode; the transparent layer has a plurality of strips extending in a first direction and arranged in a second direction perpendicular to the first direction; the low refractive layer has a portion disposed between the band portions adjacent to each other in the second direction, the transparent layer has a higher oil repellency with respect to the low refractive index layer than the third principal surface; The display device according to claim 12.
14. a protective layer covering the first main surface and the low refractive index layer; the protective layer has a refractive index equivalent to that of the second transparent substrate; The display device according to claim 10.
15. a protective layer covering the transparent layer and the low refractive index layer; the protective layer has a refractive index equivalent to that of the second transparent substrate; The display device according to claim 11.
16. a protective layer covering the third main surface and the low refractive index layer; the protective layer has a refractive index equivalent to that of the third transparent substrate; The display device according to claim 12.
17. a protective layer covering the transparent layer and the low refractive index layer; the protective layer has a refractive index equivalent to that of the third transparent substrate; The display device according to claim 13.
18. The protective layer is disposed between adjacent bottom portions.
17. The display device according to claim 14 or 16.
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