Foldable Display

Abstract

A foldable display (1) comprises: a case unit (2) including hinge members (2h1, 2h2, 2h3), and a first case (2a) and a second case (2b) that are connected to each other via the hinge members (2h1, 2h2, 2h3); and a flexible display panel (8) including a flexibly display layer (5) and a support substrate (3). A third portion (BR) of the support substrate (3) includes a first region that overlaps with step portions (2d1, 2d2) of the case unit (2) under a first state in which the flexible display panel (8) is not bent, and a second region that overlaps with a flat portion (2P) of the case unit (2) under the first state. A first proportion, in the first region of the support substrate (3), of the volume of an opening (3d) of a group of openings of the first region to the volume of the first region is lower than a second proportion, in the second region of the support substrate (3), of the volume of an opening (3d) of a group of openings of the second region to the volume of the second region.

Description

[Technical field]

[0001] The present disclosure relates to a foldable display. [Background technology]

[0002] In the field of foldable displays, there is a problem that satisfactory flexibility cannot be obtained, and research to improve the flexibility is being actively conducted.

[0003] For example, Patent Document 1 describes a configuration in which an opening is provided in a back plate of a foldable display to maintain the shape and prevent sagging or deformation when the display is repeatedly bent (folded) and unbent (open) states.

[0004] Furthermore, Patent Document 2 describes a configuration in which, in order to improve flexibility, when the foldable display is bent (folded), a flexible frame provided in the foldable display is provided with multiple openings so that the proportion of the openings is large at the center of the bend where the curvature is large, and multiple openings are provided in parts of the flexible frame provided in the foldable display where the curvature is small so that the proportion of the openings is smaller. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent Publication "US9983424B2" [Patent Document 2] International Patent Publication "WO2019 / 088372A1" Summary of the Invention [Problem to be solved by the invention]

[0006] In the foldable displays described in Patent Documents 1 and 2, an opening is provided in a back plate or flexible frame provided in the foldable display from the viewpoint of improving flexibility, without considering the occurrence of a step in a housing unit including a hinge member generally provided in the foldable display. Therefore, in the foldable displays described in Patent Documents 1 and 2, the structure is greatly affected by the step occurring in the housing unit including the hinge member, and it is not possible to ensure a satisfactory level of impact resistance of the foldable display. Or, if an attempt is made to ensure impact resistance, the flexibility is adversely deteriorated, and it is not possible to ensure both impact resistance and flexibility at the same time.

[0007] In the foldable display described in Patent Document 1, in order to protect the bent portion and prevent sagging or deformation of the bent portion, an additional layer of inorganic material is provided as a back plate in addition to the plate having an opening. However, since the addition of such an inorganic material layer deteriorates the bendability, it is not possible to ensure satisfactory bendability in a foldable display with a large curvature or a foldable display with two types of curvature.

[0008] Furthermore, the foldable display described in Patent Document 2 describes a configuration in which a silicone layer is provided to fill the openings in the support substrate. However, when a silicone layer is provided in this manner, it is difficult to ensure a satisfactory level of flexibility, and unevenness in the silicone application that occurs during the manufacturing process can easily result in the appearance of the display being significantly poor.

[0009] One aspect of the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a foldable display that has improved impact resistance and excellent flexibility compared to conventional foldable displays. [Means for solving the problem]

[0010] In order to solve the above problems, the foldable display of the present disclosure has the following features: a housing unit including a hinge member and a first housing and a second housing connected via the hinge member; a flexible display panel including a flexible display layer and a supporting substrate; the support substrate is provided between the flexible display layer and the housing unit; a first portion of the support substrate is fixed to the first housing, a second portion of the support substrate is fixed to the second housing, and the flexible display panel is fixed to the housing unit; a surface of the first housing facing the support substrate and a surface of the second housing facing the support substrate are arranged to be aligned on the same plane, and in a first state in which the flexible display panel is in an unbent state, the housing unit has a flat portion that is flat with respect to the same plane and one or more stepped portions that have a step with respect to the same plane; the support substrate has a third portion between the first portion and the second portion of the support substrate; the third portion of the support substrate includes a first region overlapping the step portion and a second region overlapping the flat portion in the first state, A first ratio of a volume of the openings of the opening group in the first region to a volume of the first region in the first region of the supporting substrate is lower than a second ratio of a volume of the openings of the opening group in the second region to a volume of the second region in the second region of the supporting substrate. Effect of the Invention

[0011] According to one aspect of the present disclosure, a foldable display having improved impact resistance and excellent flexibility compared to conventional foldable displays can be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the unbent state (open state) of the foldable display of embodiment 1, and is a cross-sectional view showing a schematic configuration of the foldable display of embodiment 1. [Diagram 2] FIG. 2 is a diagram showing the foldable display of the first embodiment in a bent (folded) state. [Diagram 3] 3(a), (b), and (c) are diagrams showing an example of an opening pattern provided in a support substrate included in the foldable display of the first embodiment. FIG. [Figure 4] FIG. 1A is a diagram showing the size of openings and the pitch of openings in an example of an opening pattern provided on a support substrate provided in the foldable display of embodiment 1, and FIG. 1B and FIG. 1C are diagrams comparing the size of openings in an example of an opening pattern provided on a support substrate provided in the foldable display of embodiment 1 with the size of pixels in an example of a pixel provided in the foldable display of embodiment 1. [Diagram 5] FIG. 2 is a diagram for explaining the relationship between one opening in an example of an opening pattern provided in a support substrate provided in the foldable display of embodiment 1 and the size of a pixel in an example of a pixel provided in the foldable display of embodiment 1. [Figure 6] 1 is a diagram showing a schematic configuration of a flexible display panel provided in the foldable display of embodiment 1. FIG. [Figure 7] FIG. 2 is a diagram showing a non-bent state (open state) of a foldable display which is a modification of the first embodiment, and is a cross-sectional view showing a schematic configuration of the foldable display which is a modification of the first embodiment. [Figure 8] FIG. 13 is a diagram showing a foldable display according to a modified example of the first embodiment in a bent (folded) state. [Figure 9] FIG. 2 is a diagram showing evaluation results of impact resistance of the foldable display of the first embodiment and a foldable display that is a modified example of the first embodiment. [Figure 10] FIG. 1 is a diagram showing the evaluation results of a bending test comparing the case where the first film layer of the cushion layer provided in the foldable display of embodiment 1 and the foldable display that is a modified example of embodiment 1 is a plastic film and the case where the first film layer is a metal film. [Figure 11]FIG. 1 is a diagram showing the results of an evaluation of impact resistance comparing the first adhesive layer of the cushion layer provided in the foldable display of embodiment 1 and the foldable display that is a modified example of embodiment 1, when the first adhesive layer is made of a hard adhesive and when the first adhesive layer is made of a soft adhesive. [Figure 12] FIG. 11 is a diagram showing an example of an opening pattern provided in a support substrate included in the foldable display of the second embodiment. [Figure 13] FIG. 11 is a diagram showing a non-bent state (open state) of the foldable display of embodiment 3, and is a cross-sectional view showing a schematic configuration of the foldable display of embodiment 3. [Figure 14] FIG. 11 is a diagram showing a bent (folded) state of the foldable display of the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The following describes an embodiment of the present invention with reference to Figures 1 to 14. For the sake of convenience, components having the same functions as those described in a specific embodiment are denoted by the same reference numerals, and descriptions thereof may be omitted.

[0014] [Embodiment 1] FIG. 1 is a diagram showing a foldable display 1 of embodiment 1 in a non-bent state (open state), and is a cross-sectional view showing a schematic configuration of the foldable display 1 of embodiment 1. As shown in FIG.

[0015] As shown in Fig. 1, the foldable display 1 includes a housing unit 2 including hinge members 2h1, 2h2, and 2h3, a first housing 2a and a second housing 2b connected via the hinge members 2h1, 2h2, and 2h3, and a flexible display panel 8 including a support substrate 3 and a flexible display layer 5. In an X-direction X that is a depth direction in Fig. 1 perpendicular to a Y-direction Y that is a left-right direction in Fig. 1, the first housing 2a and the second housing 2b are connected via the hinge members 2h1, 2h2, and 2h3, although this is not shown in the figure.

[0016] In this embodiment, as shown in FIG. 1, the foldable display 1 further includes a cushion layer 4 described later between the support substrate 3 and the flexible display layer 5, includes a functional layer 6 and a flexible cover 7 described later as upper layers of the flexible display layer 5, and includes a housing cover 19 as a lower layer of the housing unit 2. However, the present invention is not limited to this. That is, in this embodiment, the flexible display panel 8 includes the support substrate 3, the cushion layer 4, the flexible display layer 5, the functional layer 6, and the flexible cover 7. However, the present invention is not limited to this. The flexible display panel 8 may include the support substrate 3 and the flexible display layer 5. The foldable display 1 does not need to include the housing cover 19.

[0017] The support substrate 3 is provided between the housing unit 2 and the flexible display layer 5. A region NBR1 including one end of the support substrate 3, which is an example of a first portion of the support substrate 3, is fixed to the first housing 2a, and a region NBR2 including the other end of the support substrate 3, which is an example of a second portion of the support substrate 3, is fixed to the second housing 2b, and the flexible display panel 8 is fixed to the housing unit 2. When the region NBR1 including one end of the support substrate 3 is fixed to the first housing 2a and the region NBR2 including the other end of the support substrate 3 is fixed to the second housing 2b, for example, an adhesive or screws may be used.

[0018] The portion including region NBR1 including one end of the support substrate 3 and region NBR2 including the other end of the support substrate 3 is the non-flexible region of the flexible display panel 8, and the portion including the third portion BR of the support substrate 3 between region NBR1 including one end of the support substrate 3 and region NBR2 including the other end of the support substrate 3 is the curved region of the flexible display panel 8.

[0019] 1, in a first state in which the surface of the first housing 2a facing the support substrate 3 and the surface of the second housing 2b facing the support substrate 3 are arranged side by side on the same plane and the flexible display panel 8 is in an unbent state, the housing unit 2 has a flat portion 2P that is flat with respect to the same plane and one or more stepped portions 2d1-2d2 that have a step with respect to the same plane. In the present embodiment, a case in which the housing unit 2 has two types of stepped portions 2d1-2d2 will be described as an example, but the present invention is not limited to this. For example, the housing unit may have three or more types of stepped portions as in a modified example of the present embodiment described later, or the housing unit may have one type of stepped portion as in a third embodiment described later.

[0020] In the first state described above, the third portion BR of the support substrate 3 includes a first region (e.g., including region B shown by dotted lines in FIG. 1) overlapping with the stepped portions 2d1 and 2d2, and a second region (e.g., including region A shown by dotted lines in FIG. 1) overlapping with the flat portion 2P. That is, the first region of the third portion BR of the support substrate 3 is a combined region of the third portion BR of the support substrate 3 overlapping with the stepped portion 2d1 and the region of the third portion BR of the support substrate 3 overlapping with the stepped portion 2d2, and the second region of the third portion BR of the support substrate 3 is a region of the third portion BR of the support substrate 3 overlapping with the flat portion 2P.

[0021] As shown in FIG. 1, a first ratio of the volume of the openings 3d of the opening group in the first region to the volume of the first region in the first region of the support substrate 3 is lower than a second ratio of the volume of the openings 3d of the opening group in the second region to the volume of the second region in the second region of the support substrate 3.

[0022] 1, flat portion 2P is formed by hinge members 2h1, 2h2, and 2h3. Step portion 2d1 includes a gap between first housing 2a and hinge member 2h1, and step portion 2d2 includes a gap between second housing 2b and hinge member 2h3.

[0023] FIG. 2 is a diagram showing the foldable display 1 of the first embodiment in a bent (folded) state.

[0024] As shown in FIG. 2, the surface of the first housing 2a facing the support substrate 3 and the surface of the second housing 2b facing the support substrate 3 are arranged to face each other, and the foldable display 1 is folded with the distance between the first housing 2a and the second housing 2b shortened, i.e., in the second state in which the flexible display panel 8 is in a bent state, the flexible display panel 8 is teardrop-shaped.

[0025] As shown in FIG. 2, when the foldable display 1 is in a folded state, a gap 2S1 is generated between the hinge members 2h1 and 2h2, and a gap 2S2 is generated between the hinge members 2h2 and 2h3.

[0026] 3(a), 3(b), and 3(c) are diagrams showing an example of an opening pattern provided in the support substrate 3 included in the foldable display 1 of the first embodiment.

[0027] The opening pattern provided in the support substrate 3 shown in (a) of Figure 3 is an example where the ratio of the volume of the openings 3d of the opening group in the corresponding region to the volume of the corresponding region is approximately 65%, i.e., the ratio of the volume of the material of the support substrate 3 in the corresponding region to the volume of the corresponding region is approximately 35%.

[0028] The opening pattern provided in the supporting substrate 3 shown in (b) of Figure 3 is an example of a case where the volume of the openings 3d of the opening group in the corresponding region accounts for approximately 50% of the volume of the corresponding region, i.e., the volume of the material of the supporting substrate 3 in the corresponding region accounts for approximately 50% of the volume of the corresponding region.

[0029] The opening pattern provided in the supporting substrate 3 shown in (c) of Figure 3 is an example where the ratio of the volume of the openings 3d of the opening group in the corresponding region to the volume of the corresponding region is approximately 40%, i.e., the ratio of the volume of the material of the supporting substrate 3 in the corresponding region to the volume of the corresponding region is approximately 60%.

[0030] Note that the Y direction Y shown in FIGS. 3(a), 3(b), and 3(c) is the same as the Y direction Y shown in FIG. 1, and the X direction X shown in FIGS. 3(a), 3(b), and 3(c) is the same as the X direction X shown in FIG. 1.

[0031] In the present embodiment, as shown in Figures 3(a), 3(b), and 3(c), the openings 3d in the opening pattern provided on the support substrate 3 are formed as rectangles whose length in the X direction is longer than their length in the Y direction, but the shape of the openings 3d in the opening pattern provided on the support substrate 3 is not particularly limited. For example, the shape of the openings 3d may be a circle, a hexagon, a diamond, or a Y shape.

[0032] In the present embodiment, the case where each of the openings 3d of the opening group provided in the support substrate 3 is an opening that penetrates from the surface of the support substrate 3 on the flexible display layer 5 side to the surface of the support substrate 3 on the housing unit 2 side will be described as an example, but the present invention is not limited to this. For example, each of the openings 3d of the opening group provided in the support substrate 3 may be an opening that penetrates from the surface of the support substrate 3 on the flexible display layer 5 side to the surface of the support substrate 3 on the housing unit 2 side, and the remaining openings 3d may be an opening that does not penetrate from the surface of the support substrate 3 on the flexible display layer 5 side to the surface of the support substrate 3 on the housing unit 2 side. Furthermore, each of the openings 3d of the opening group provided in the support substrate 3 may be an opening that does not penetrate from the surface of the support substrate 3 on the flexible display layer 5 side to the surface of the support substrate 3 on the housing unit 2 side.

[0033] In this embodiment, the case where the supporting substrate 3 is a metal substrate formed to a thickness of 150 μm will be described as an example, but the present invention is not limited to this, and the supporting substrate 3 may be a resin substrate.

[0034] The material of the metal substrate may be, for example, a material containing at least one of stainless steel, aluminum, titanium, and copper.

[0035] Examples of materials that can be used for the resin substrate include polyester resin, acrylic resin, polycarbonate, and carbon fiber reinforced plastic.

[0036] In addition, in consideration of ease of manufacturing the support substrate 3 and ensuring the flexibility of the support substrate 3, the thickness of the support substrate 3 is preferably 100 μm or more and 300 μm or less.

[0037] When the supporting substrate 3 is a resin substrate, for example, punching or die cutting can be performed to form the opening group, i.e., the plurality of openings 3d, in the supporting substrate 3. On the other hand, when the supporting substrate 3 is a metal substrate, for example, exposure and development using a mask pattern are performed, followed by etching to form the opening group, i.e., the plurality of openings 3d in the supporting substrate 3.

[0038] In the third portion BR of the support substrate 3 in the first state described above, a first ratio of the volume of the openings 3d of the opening group in the first region to the volume of the first region overlapping with the step portions 2d1-2d2 is preferably 60% or less in terms of ensuring the impact resistance of the foldable display 1. On the other hand, in the third portion BR of the support substrate 3 in the first state described above, a second ratio of the volume of the openings 3d of the opening group in the second region to the volume of the second region overlapping with the flat portion 2P is preferably 55% or more and 75% or less as long as it is larger than the first ratio in terms of ensuring the flexibility of the foldable display 1.

[0039] Therefore, in a first region overlapping with the step portions 2d1 and 2d2 in the third portion BR of the support substrate 3, for example, the opening pattern provided in the support substrate 3 shown in (b) of Figure 3 or the opening pattern provided in the support substrate 3 shown in (c) of Figure 3 can be preferably used, and in a second region overlapping with the flat portion 2P in the third portion BR of the support substrate 3, for example, the opening pattern provided in the support substrate 3 shown in (a) of Figure 3 can be preferably used.

[0040] FIG. 4(a) is a diagram showing the size of the openings 3d and the pitch of the openings 3d in one example of an opening pattern provided in the support substrate 3 included in the foldable display 1 of the first embodiment.

[0041] FIG. 4(a) illustrates the line width WA of the supporting substrate material between the openings 3d in the Y direction Y, the width WB of the openings 3d in the Y direction Y, the line width WC of the supporting substrate material between the openings 3d in the X direction X, and the width WD of the openings 3d in the X direction X.

[0042] In this embodiment, a case will be described as an example in which the supporting substrate 3 is provided with an opening pattern consisting of a plurality of openings 3d of the same shape, in which the width WD of the openings 3d in the X-direction X is larger than the width WB of the openings 3d in the Y-direction Y, and the line width WC of the supporting substrate material between the openings 3d in the X-direction X is larger than the line width WA of the supporting substrate material between the openings 3d in the Y-direction Y; however, the present invention is not limited to this. As described above, if the first ratio of the volume of the openings 3d of the opening group in the first region to the volume of the first region in the first region of the support substrate 3 is lower than the second ratio of the volume of the openings 3d of the opening group in the second region to the volume of the second region in the second region of the support substrate 3, for example, the shapes of the openings in the opening pattern provided on the support substrate 3 do not need to be identical, and the relationship between the line width WA of the support substrate material between the openings 3d in the Y direction Y and the line width WC of the support substrate material between the openings 3d in the X direction X can be appropriately determined, and the relationship between the width WB of the opening in the Y direction Y and the width WD of the opening in the X direction X can be appropriately determined.

[0043] (b) of Figure 4 is a diagram comparing the size of an opening 3d in an example of an opening pattern provided in a support substrate 3 provided in the foldable display 1 of embodiment 1 with the size of a pixel PIX in an example of a pixel provided in the foldable display 1 of embodiment 1, in which multiple sub-pixels are arranged in an S-stripe arrangement.

[0044] As shown in (b) of Figure 4, a plurality of pixels PIX are arranged on one of the openings 3d in the group of openings provided in the support substrate 3. The pixels PIX are provided in the flexible display layer 5 and each pixel has a red sub-pixel RSP, a green sub-pixel GSP, and a blue sub-pixel BSP arranged in an S-stripe configuration.

[0045] (c) of Figure 4 is a diagram comparing the size of an opening 3d in an example of an opening pattern provided in a support substrate 3 provided in the foldable display 1 of embodiment 1 with the size of a pixel PIX' in which multiple sub-pixels are arranged in a diamond pentatile arrangement, which is an example of a pixel provided in the foldable display 1 of embodiment 1.

[0046] As shown in (c) of Figure 4, a plurality of pixels PIX' are arranged on one of the openings 3d in the group of openings provided in the support substrate 3, and are provided in the flexible display layer 5 and have red sub-pixels RSP, green sub-pixels GSP, and blue sub-pixels BSP arranged in a diamond pentatile pattern.

[0047] FIG. 5 is a diagram illustrating the relationship between one opening 3d in an example of an opening pattern provided in a support substrate 3 provided in the foldable display 1 of embodiment 1 and the size of pixels PIX and PIX' in an example of a pixel provided in the foldable display 1 of embodiment 1.

[0048] 5, that is, in the case of the arrangement example 1 of the opening group consisting of the openings 3d, the line width WA of the supporting substrate material between the openings 3d in the Y direction Y is 90 μm, the width WB of the openings 3d in the Y direction Y is 225 μm, the line width WC of the supporting substrate material between the openings 3d in the X direction X is 150 μm, and the width WD of the openings 3d in the X direction X is 2220 μm. In this case, the ratio of the volume of the openings 3d of the opening group in the corresponding region to the volume of the corresponding region is about 65%, that is, the ratio of the volume of the material of the supporting substrate 3 in the corresponding region to the volume of the corresponding region (the material occupancy rate of the supporting substrate 3) is about 35%, and this is an opening pattern provided in the supporting substrate 3 shown in (a) of FIG. 3 that can be suitably used in the second region overlapping the flat portion 2P in the third portion BR of the supporting substrate 3.

[0049] 5, that is, in the case of Arrangement Example 2 of the opening group consisting of the openings 3d, the line width WA of the supporting substrate material between the openings 3d in the Y direction Y is 195 μm, the width WB of the openings 3d in the Y direction Y is 221 μm, the line width WC of the supporting substrate material between the openings 3d in the X direction X is 154 μm, and the width WD of the openings 3d in the X direction X is 2221 μm. In this case, the ratio of the volume of the openings 3d of the opening group in the corresponding region to the volume of the corresponding region is about 50%, that is, the ratio of the volume of the material of the supporting substrate 3 in the corresponding region to the volume of the corresponding region (the material occupancy rate of the supporting substrate 3) is about 50%, and the third portion BR of the supporting substrate 3 can be suitably used in the first region overlapping with the step portions 2d1 and 2d2.

[0050] In either case of Arrangement Example 1 or Arrangement Example 2 of the opening 3d shown in FIG. 5, if the size of one pixel PIX in which multiple sub-pixels are arranged in an S-stripe arrangement is 100 μm × 100 μm, two pixels PIX can be arranged in the Y-direction Y of the opening 3d, and 22 pixels PIX can be arranged in the X-direction X of the opening 3d. Thus, on one opening 3d of the opening group provided in the support substrate 3, 44 pixels PIX provided in the flexible display layer 5 and in which red sub-pixels RSP, green sub-pixels GSP, and blue sub-pixels BSP are arranged in an S-stripe arrangement are arranged.

[0051] Furthermore, in either case of Arrangement Example 1 or Arrangement Example 2 of the opening 3d shown in Figure 5, if the size of one pixel PIX' in which multiple sub-pixels are arranged in a diamond pentile pattern is 60 μm x 60 μm, three pixels PIX' can be arranged in the Y direction Y of the opening 3d, and 37 pixels PIX' can be arranged in the X direction X of the opening 3d, and 111 pixels PIX' in which red sub-pixels RSP, green sub-pixels GSP, and blue sub-pixels BSP are arranged in a diamond pentile pattern are arranged on one opening 3d of the opening group provided in the support substrate 3.

[0052] Like the applicable arrangement example of the openings 3d shown in FIG. 5 , the arrangement examples of the openings 3d are not limited to the above-mentioned arrangement example 1 and arrangement example 2 of the openings 3d, and for example, the line width WA of the supporting substrate material between the openings 3d in the Y direction Y can be 50 μm or more and 500 μm or less, the width WB of the openings 3d in the Y direction Y can be 100 μm or more and 400 μm or less, the line width WC of the supporting substrate material between the openings 3d in the X direction X can be 100 μm or more and 300 μm or less, and the width WD of the openings 3d in the X direction X can be 1000 μm or more and 4000 μm or less.

[0053] In the case of the applicable arrangement example of the openings 3d shown in FIG. 5, when the pixel size is 40 μm × 40 μm or more and 400 μm × 400 μm or less, 1 or more and 10 or less pixels can be arranged in the Y direction Y of the opening 3d, and 2 or more and 100 or less pixels can be arranged in the X direction X of the opening 3d, and 2 or more and 1000 or less pixels provided in the flexible display layer 5 are arranged on one opening 3d of the opening group provided in the support substrate 3.

[0054] FIG. 6 is a diagram showing a schematic configuration of the flexible display panel 8 provided in the foldable display 1 of the first embodiment.

[0055] As shown in FIG. 6, in this embodiment, a flexible display panel 8 includes a support substrate 3, a cushion layer 4, a flexible display layer 5, a functional layer 6, and a flexible cover .

[0056] In this embodiment, a case will be described in which the cushion layer 4 provided between the support substrate 3 and the flexible display layer 5 includes a first adhesive layer 14, a first film layer 15, a second adhesive layer 16, a second film layer 17, and a third adhesive layer 18 in this order from the support substrate 3 side, but the present invention is not limited to this. For example, the cushion layer 4 preferably includes one or more resin layers, but is not limited to this, and may include a layer formed of a metal material.

[0057] At least one of the first film layer 15 and the second film layer 17 is preferably made of, for example, PET, PEN, polyimide resin, acrylic resin, etc. In this embodiment, the first film layer 15 and the second film layer 17 are each made of PET, but are not limited to this.

[0058] The elastic modulus of the first film layer 15 and the elastic modulus of the second film layer 17 are preferably 1 GPa or more and 8 GPa or less, and more preferably 3 GPa or more and 6 GPa or less.

[0059] In this embodiment, the elastic modulus of first film layer 15 is set to be higher than the elastic modulus of second film layer 17.

[0060] The first adhesive layer 14 is preferably formed to have a thickness of 15 μm or more and 75 μm or less. The first film layer 15 is preferably formed to have a thickness of 20 μm or more and 100 μm or less, and more preferably formed to have a thickness of 25 μm or more and 75 μm or less. The second adhesive layer 16 is preferably formed to have a thickness of 15 μm or more and 100 μm or less. The second film layer 17 is preferably formed to have a thickness of 20 μm or more and 100 μm or less. The third adhesive layer 18 is preferably formed to have a thickness of 15 μm or more and 75 μm or less.

[0061] The first adhesive layer 14, the second adhesive layer 16, and the third adhesive layer 18 may be formed using any type of adhesive. 4Pa or more, 1.0×10 6 A hard adhesive (relatively hard adhesive) having a compressive stress of 500 KPa or more and 1200 KPa or less, measured under conditions of a test speed of 0.5 mm / min and a compressive strain of 40%, may be used. The shear storage modulus at 25°C is 2.0 x 10 4 Pa or more, 5.0×10 4 A soft adhesive (relatively soft adhesive) having a compressive stress of 80 KPa or more and 300 KPa or less, measured under conditions of a test speed of 0.5 mm / min and a compressive strain of 40%, may be used.

[0062] In this embodiment, the first adhesive layer 14 has a shear storage modulus of 5.0×10 4 Pa or more, 1.0×10 6 The impact resistance of the foldable display 1 can be further improved by forming the foldable display 1 using a hard adhesive (a relatively hard adhesive) having a compressive stress of 500 KPa or more and 1,200 KPa or less, measured under conditions of a test speed of 0.5 mm / min and a compressive strain of 40%.

[0063] The flexible display layer 5 includes, for example, a flexible substrate, a thin film transistor layer, and a display layer including a plurality of pixels each including a plurality of sub-pixels. The display layer may be, for example, a liquid crystal display layer, or a display layer including a light-emitting element for each of a plurality of sub-pixels. When the display layer is a display layer including a light-emitting element for each of a plurality of sub-pixels, the light-emitting element may include a light-emitting layer including quantum dots or an organic light-emitting layer. The flexible display layer 5 is preferably formed to have a thickness of, for example, 10 μm or more and less than 100 μm, but is not limited thereto.

[0064] As shown in Figure 6, the functional layer 6 provided on the flexible display layer 5 includes a fourth adhesive layer 9, a touch panel 10, a fifth adhesive layer 11, a polarizing plate 12, and a sixth adhesive layer 13, in this order from the flexible display layer 5 side.

[0065] The fourth adhesive layer 9 is preferably formed to a thickness of 15 μm or more and 50 μm or less. The touch panel 10 is preferably formed to a thickness of 30 μm or more and 50 μm or less. The fifth adhesive layer 11 is preferably formed to a thickness of 15 μm or more and 50 μm or less. The polarizing plate 12 is preferably formed to a thickness of 30 μm or more and 50 μm or less. The sixth adhesive layer 13 is preferably formed to a thickness of 15 μm or more and 50 μm or less. The fourth adhesive layer 9, the fifth adhesive layer 11, and the sixth adhesive layer 13 may be formed using any type of adhesive. For example, the above-mentioned soft adhesive (relatively soft adhesive) or the above-mentioned hard adhesive (relatively hard adhesive) may be used.

[0066] As shown in Fig. 6, a flexible cover 7 is provided on the functional layer 6. A well-known window film that is hard-coated is one example of the flexible cover 7. The flexible cover 7 is preferably formed to have a thickness of 50 µm or more and 100 µm or less.

[0067] FIG. 7 is a diagram showing a non-bent state (open state) of a foldable display 1a which is a modification of the first embodiment, and is a cross-sectional view showing a schematic configuration of the foldable display 1a which is a modification of the first embodiment.

[0068] 7, the housing unit 2' provided in the foldable display 1a includes hinge members 2h1, 2h2', and 2h3. A recess 2d3 that is a step portion is provided in a part of the hinge member 2h2'. Therefore, the housing unit 2' provided in the foldable display 1a differs from the foldable display 1 described above in that it further includes the recess 2d3 that is a step portion in addition to the step portions 2d1 and 2d2.

[0069] An adhesive may be formed in the recess 2d3, which is a step portion. In this case, a part of the third portion BR of the support substrate 3a can be fixed to the hinge member 2h2' by the adhesive. Note that the type of adhesive to be used and the method of forming the adhesive may be, for example, the type of adhesive and the method of forming the adhesive described in International Patent Publication "WO2020 / 065936A1".

[0070] In the present embodiment, the case where the recess 2d3 is provided as a step portion in a part of the hinge member 2h2' has been described as an example, but the present invention is not limited to this. Although not shown, a protrusion may be provided as a step portion in a part of the hinge members 2h1, 2h2', and 2h3. An example of the protrusion may be a member such as a screw provided in the hinge members 2h1, 2h2', and 2h3.

[0071] 7, the third portion BR of the support substrate 3a in the first state described above includes a first region (e.g., including region B and region C shown by dotted lines in FIG. 7) overlapping with the steps 2d1 and 2d2 and the recess 2d3, and a second region (e.g., including region A shown by dotted lines in FIG. 7) overlapping with the flat portion 2P. That is, the first region of the third portion BR of the support substrate 3a is a region that combines the region of the third portion BR of the support substrate 3 that overlaps with the step portion 2d1, the region of the third portion BR of the support substrate 3a that overlaps with the step portion 2d2, and the region of the third portion BR of the support substrate 3a that overlaps with the recess 2d3, and the second region of the third portion BR of the support substrate 3a is the region of the third portion BR of the support substrate 3a that overlaps with the flat portion 2P.

[0072] As shown in FIG. 7, a first ratio of the volume of the openings 3d of the opening group in the first region to the volume of the first region in the first region of the support substrate 3a is lower than a second ratio of the volume of the openings 3d of the opening group in the second region to the volume of the second region in the second region of the support substrate 3a.

[0073] FIG. 8 is a diagram showing a foldable display 1a according to a modification of the first embodiment in a bent (folded) state.

[0074] As shown in FIG. 8, in the folded state in which the surface of the first housing 2a facing the support substrate 3a and the surface of the second housing 2b facing the support substrate 3a are arranged to face each other and the distance between the first housing 2a and the second housing 2b is shortened, that is, in the second state in which the flexible display panel 8a is in a bent state, the flexible display panel 8a is teardrop-shaped.

[0075] As shown in FIG. 8, the recess 2d3 is preferably provided along the bending center of the flexible display panel 8a.

[0076] FIG. 9 is a diagram showing the evaluation results of impact resistance of the foldable display 1 of the first embodiment and a foldable display 1a which is a modified example of the first embodiment.

[0077] The evaluation results of impact resistance shown in FIG. 9 are the results of performing each evaluation after the foldable display 1 and the foldable display 1a were placed in the first state described above.

[0078] The ball drop evaluation was performed by dropping a specified steel ball (weight 24 g, diameter 18 mm) from a specified height onto the flexible cover 7, the pen drop evaluation was performed by dropping a specified pen (weight 19 g, elastomer tip) from a specified height onto the flexible cover 7, and the step feel (pen tracing) evaluation was performed by manually sliding the pen tip against the flexible cover 7 with force to confirm the feel.

[0079] The material occupancy rate of the supporting substrate shown in Figure 9 means the ratio of the volume of the material of the supporting substrate 3 in the corresponding region to the volume of the corresponding region (the material occupancy rate of the supporting substrate 3), and (100% - the material occupancy rate of the supporting substrate 3) is the ratio of the volume of the opening 3d of the supporting substrate 3 in the corresponding region to the volume of the corresponding region.

[0080] The height shown in Figure 9 indicates the maximum height at which defects such as bright spots or bright lines do not appear when a ball is dropped from 5 cm increments on the foldable display 1·1a after the evaluation described above. Also, the (※) in Figure 9 indicates the upper limit height of the evaluation performed this time at which defects such as bright spots or bright lines do not appear. The upper limit height was determined in order to protect the housing unit, but in reality, defects may not appear even if the ball is dropped from an even higher position.

[0081] In a ball drop evaluation, when a ball was dropped on the positions of the step portions 2d1, 2d2, and 2d3, it was confirmed that when the material occupancy rate of supporting substrate 3 was 40% or more and 50% or less (the occupancy rate of openings 3d of supporting substrate 3 was 50% or more and 60% or less), the impact resistance was improved by 5 cm compared to when the material occupancy rate of supporting substrate 3 was 30% or more and 35% or less (the occupancy rate of openings 3d of supporting substrate 3 was 65% or more and 70% or less). Also, when a ball is dropped on the edge of the stepped portions 2d1, 2d2, and 2d3, it can be confirmed that when the material occupancy rate of the support substrate 3 is 40% or more and 50% or less (the occupancy rate of the openings 3d of the support substrate 3 is 50% or more and 60% or less) and when the material occupancy rate of the support substrate 3 is 50% or more and 65% or less (the occupancy rate of the openings 3d of the support substrate 3 is 35% or more and 50% or less), the impact resistance is improved by 5 cm compared to when the material occupancy rate of the support substrate 3 is 30% or more and 35% or less (the occupancy rate of the openings 3d of the support substrate 3 is 65% or more and 70% or less). Furthermore, it can be confirmed that when the material occupancy rate of the support substrate 3 is 70% or more and 80% or less (the occupancy rate of the openings 3d of the support substrate 3 is 20% or more and 30% or less), the impact resistance is improved by 10 cm compared to when the material occupancy rate of the support substrate 3 is 30% or more and 35% or less (the occupancy rate of the openings 3d of the support substrate 3 is 65% or more and 70% or less). For the above reasons, it is preferable that the material occupancy rate of supporting substrate 3 is 40% or more (the occupancy rate of opening 3d of supporting substrate 3 is 60% or less) even in the regions overlapping with the edges of step portions 2d1, 2d2, and 2d3. Note that for the flat portion of hinge member 2h2', which is a highly flat portion, and the flat portions of hinge members 2h1, 2h2, and 2h3, and first housing 2a and second housing 2b, which are non-bent portions, the impact resistance is originally high, so that changing the material occupancy rate of supporting substrate 3 (the occupancy rate of opening 3d of supporting substrate 3) did not improve the impact resistance.

[0082] In the pen drop evaluation, when the pen was dropped on the stepped portions 2d1, 2d2, and 2d3 and when the pen was dropped on the edge of the stepped portions 2d1, 2d2, and 2d3, the impact resistance was improved when the material occupancy rate of the support substrate 3 was 40% or more (the opening 3d occupancy rate of the support substrate 3 was 60% or less). When the material occupancy rate of the support substrate 3 was 50% or more, the impact resistance effect was even greater. Note that the flat portion of the hinge member 2h2', the flat portion of the hinge members 2h1, 2h2, and 2h3, which are highly flat portions, and the first housing 2a and the second housing 2b, which are non-bending portions, already have high impact resistance, so changing the material occupancy rate of the support substrate 3 (opening 3d occupancy rate of the support substrate 3) did not improve the impact resistance.

[0083] The evaluation of the step sensation (pen tracing) was only performed for the positions of the step portions 2d1, 2d2, and 2d3, and it was confirmed that when the material occupancy rate of the supporting substrate 3 is 40% or more and 50% or less (the occupancy rate of the openings 3d of the supporting substrate 3 is 50% or more and 60% or less), the step sensation is significantly reduced compared to when the material occupancy rate of the supporting substrate 3 is 30% or more and 35% or less (the occupancy rate of the openings 3d of the supporting substrate 3 is 65% or more and 70% or less), and that when the material occupancy rate of the supporting substrate 3 is 50% or more (the occupancy rate of the openings 3d of the supporting substrate 3 is 50% or less), the step sensation is almost eliminated.

[0084] FIG. 10 is a diagram showing the results of a bending test comparing the first film layer 15 of the cushion layer 4 provided in the foldable display 1 of embodiment 1 and the foldable display 1a, which is a modified example of embodiment 1, when the first film layer 15 is a plastic film and when the first film layer 15 is a metal film.

[0085] The bending test shown in Fig. 10 is a result of checking whether peeling or the like occurs in each layer of the foldable display 1·1a depending on the number of times the foldable display 1·1a is changed from the first state described above to the second state described above and then back to the first state described above. Note that the result of the bending test shown in Fig. 10 is a result when the bending test was performed at a speed of 7 rpm.

[0086] As shown in FIG. 10, when the first film layer 15 of the cushion layer 4 is a metal film, satisfactory durability against bending cannot be obtained. However, when the first film layer 15 of the cushion layer 4 is a plastic film such as PET as in this embodiment, a foldable display 1·1a having satisfactory durability against bending can be realized. Also, the (※) in FIG. 10 indicates the upper limit of the number of times of evaluation performed this time without any defects such as peeling. Therefore, in reality, there may be cases where no defects occur at a number of times greater than the upper limit. The NG in FIG. 10 indicates that peeling occurred at that number of times, and the OK indicates that peeling did not occur at that number of times.

[0087] FIG. 11 is a diagram showing the results of an evaluation of impact resistance comparing the first adhesive layer 14 of the cushion layer 4 provided in the foldable display 1 of embodiment 1 and the foldable display 1a which is a modified example of embodiment 1, when the first adhesive layer 14 is made of a hard adhesive and when the first adhesive is made of a soft adhesive.

[0088] As shown in Fig. 11, in the pen drop evaluation, when the pen was dropped at the position of the step portions 2d1, 2d2, and 2d3 and when the pen was dropped at the edge position of the step portions 2d1, 2d2, and 2d3, in both the case where a hard adhesive was used as the first adhesive layer 14 of the cushion layer 4 and the case where a soft adhesive was used, when the material occupancy rate of the support substrate 3 was 50% or more (the opening 3d occupancy rate of the support substrate 3 was 50% or less), an improved effect on impact resistance was obtained compared to the case where the material occupancy rate of the support substrate 3 was 30% or more and 35% or less (the opening 3d occupancy rate of the support substrate 3 was 65% or more and 70% or less). In particular, when a hard adhesive was used as the first adhesive layer 14 of the cushion layer 4, a large improved effect on impact resistance was obtained when the pen was dropped at the edge position of the step portions 2d1, 2d2, and 2d3.

[0089] As described above, in the foldable display 1 of the first embodiment and the foldable display 1a which is a modification of the first embodiment, the case where the housing unit 2·2′ is composed of the first housing 2a, the second housing 2b, and the hinge members 2h1·2h2·2h3 which connect the first housing 2a and the second housing 2b, or the hinge members 2h1·2h2′·2h3 which connect the first housing 2a and the second housing 2b, has been described as an example, but is not limited thereto. For example, the housing unit may further include a third housing and another hinge member which connects either one of the first housing 2a and the second housing 2b to the third housing. Furthermore, the housing unit may include N (N is a natural number equal to or greater than 4) housings and N-1 hinge members. In this way, by applying the above-described support substrates 3·3a to a foldable display having a plurality of bending regions, a foldable display having improved impact resistance and excellent flexibility compared to conventional foldable displays can be realized.

[0090] [Embodiment 2] Next, a second embodiment of the present invention will be described with reference to FIG. 12. The foldable display of this embodiment differs from the foldable display 1-1a described in the first embodiment in that a part of the second region in contact with the first region of the support substrate is divided into a plurality of regions. The rest is as described in the first embodiment. For convenience of explanation, the same reference numerals are used for members having the same functions as those shown in the drawings of the first embodiment, and the explanation thereof will be omitted.

[0091] FIG. 12 is a diagram showing an example of an opening pattern provided in a support substrate included in the foldable display of the second embodiment.

[0092] As shown in FIG. 12, the third portion BR of the support substrate, in the first state described above, includes a first region (e.g., including region B and region C in FIG. 12) that overlaps with the step portions 2d1-2d2 and the recesses 2d3, and a second region (e.g., including region A and regions D2-D5 in FIG. 12) that overlaps with the flat portion 2P.

[0093] In this embodiment, not only in the first region overlapping with the steps 2d1-2d2 and the recess 2d3, but also in the region overlapping with the edges of the steps 2d1-2d2 and the recess 2d3, a region in which the material occupancy rate of the support substrate is 40% or more (the opening occupancy rate of the support substrate is 60% or less). Therefore, a part of the second region overlapping with the flat portion 2P is a region in which the material occupancy rate of the support substrate is 40% or more (the opening occupancy rate of the support substrate is 60% or less), and the remaining part of the second region overlapping with the flat portion 2P is a region in which the material occupancy rate of the support substrate is less than 40% (the opening occupancy rate of the support substrate is greater than 60%). With this configuration, as described above in the first embodiment, a foldable display with even higher impact resistance can be realized.

[0094] In this embodiment, as described above, an example has been given in which an area in which the material occupancy rate of the support substrate is 40% or more (the opening occupancy rate of the support substrate is 60% or less) is formed not only in the first area overlapping with the steps 2d1·2d2 and the recess 2d3, but also in the area overlapping with the edges of the steps 2d1·2d2 and the edges of the recess 2d3. However, this is not limited to this, and an area in which the material occupancy rate of the support substrate is 40% or more (the opening occupancy rate of the support substrate is 60% or less) may be formed only in either the area overlapping with the edges of the steps 2d1·2d2 or the area overlapping with the edges of the recess 2d3.

[0095] 12, a part of the second region in contact with the first region of the support substrate is divided into a plurality of regions, and in each of the plurality of regions, the ratio of the volume of the openings of the opening group in each region to the volume of the region is different, and in each of the plurality of regions, the material occupancy rate of the support substrate in each of the plurality of regions decreases (the occupancy rate of the openings in the support substrate in each of the plurality of regions increases) as it gets farther from the first region, in a range from 40% or more of the material occupancy rate of the support substrate (the opening occupancy rate of the support substrate in each of the plurality of regions) to a value smaller than 40% (a value larger than 60% of the opening occupancy rate of the support substrate). With this configuration, it is possible to improve undulations occurring in the support substrate.

[0096] A part of the region including one end of the support substrate that is in contact with the first region and fixed to the first housing 2a, i.e., region D1 shown in Fig. 12, is divided into a plurality of regions, and in each of the plurality of regions, the ratio of the volume of the openings of the opening group in each region to the volume of the region is different, and in each of the plurality of regions, the material occupancy rate of the support substrate in each of the plurality of regions increases the farther away from the first region is in each of the plurality of regions (the occupancy rate of the openings in the support substrate in each of the plurality of regions decreases). With this configuration, the waviness occurring in the support substrate can be further improved.

[0097] In addition, a part of the region including the other end of the support substrate that is in contact with the first region and fixed to the second housing 2b, i.e., region D6 shown in Fig. 12, is divided into a plurality of regions, and in each of the plurality of regions, the ratio of the volume of the openings of the opening group in each region to the volume of the region is different, and in each of the plurality of regions, the material occupancy rate of the support substrate in each of the plurality of regions increases the farther away from the first region is, (the occupancy rate of the openings in the support substrate in each of the plurality of regions decreases). With this configuration, the waviness occurring in the support substrate can be further improved.

[0098] In this embodiment, the case where the material occupancy rate of the support substrate in each of the multiple regions decreases or increases continuously will be described as an example, but the present invention is not limited to this, and the material occupancy rate of the support substrate in each of the multiple regions may decrease or increase stepwise. When the material occupancy rate of the support substrate in each of the multiple regions changes continuously, this can be achieved by continuously increasing or decreasing the width WB of the opening 3d in the Y direction Y (see (a) of FIG. 4).

[0099] [Embodiment 3] Next, a third embodiment of the present invention will be described with reference to Figs. 13 and 14. A foldable display 1b of this embodiment differs from the foldable displays 1 and 1a described in the first and second embodiments in that the flexible display panel 8b is U-shaped when the foldable display 1b is bent (folded). The rest is as described in the first and second embodiments. For convenience of explanation, members having the same functions as those shown in the drawings of the first and second embodiments are denoted by the same reference numerals, and their explanation will be omitted.

[0100] FIG. 13 is a diagram showing a foldable display 1b of the third embodiment in a non-bent state (open state), and is a cross-sectional view showing a schematic configuration of the foldable display 1b of the third embodiment.

[0101] As shown in FIG. 13, a region NBR1 including one end of the support substrate 3b, which is an example of a first portion of the support substrate 3b, is fixed to a region including one end of the first housing 2a of the housing unit 2'', and a region NBR2 including the other end of the support substrate 3b, which is an example of a second portion of the support substrate 3b, is fixed to a region including one end of the second housing 2b of the housing unit 2'', thereby fixing the flexible display panel 8b to the housing unit 2''. The flat portion 2P of the housing unit 2'' is formed by a portion of the first housing 2a other than the region including the one end and a portion of the second housing 2b other than the region including the one end. The step portion 2d6 includes a gap between the first housing 2a and the second housing 2b.

[0102] As shown in FIG. 13, the third portion BR of the support substrate 3b, in the first state described above, includes a first region (e.g., including region E shown by dotted lines in FIG. 13) that overlaps with the step portion 2d6, and a second region (e.g., including region F shown by dotted lines in FIG. 13) that overlaps with the flat portion 2P.

[0103] As shown in FIG. 13, a first ratio of the volume of the openings 3d of the opening group in the first region to the volume of the first region in the first region of the support substrate 3b is lower than a second ratio of the volume of the openings 3d of the opening group in the second region to the volume of the second region in the second region of the support substrate 3b.

[0104] The foldable display 1b can achieve satisfactory shock resistance and bendability.

[0105] FIG. 14 is a diagram showing a foldable display 1b of the third embodiment in a bent (folded) state.

[0106] As shown in FIG. 14, in the folded state in which the surface of the first housing 2a facing the support substrate 3b and the surface of the second housing 2b facing the support substrate 3b are arranged to face each other and the distance between the first housing 2a and the second housing 2b is shortened, that is, in the second state in which the flexible display panel 8b is in a bent state, the flexible display panel 8b has a U-shape.

[0107] As described above, in the foldable display 1b of the third embodiment, the case where the housing unit 2'' is composed of the first housing 2a, the second housing 2b, and the hinge members 2h4, 2h5, and 2h6 that connect the first housing 2a and the second housing 2b has been described as an example, but the present invention is not limited to this. For example, the housing unit may further include a third housing and another hinge member that connects either one of the first housing 2a and the second housing 2b to the third housing. Furthermore, the housing unit may include N (N is a natural number of 4 or more) housings and N-1 hinge members. In this way, by applying the above-mentioned support substrate 3b to a foldable display having a plurality of bending regions, a foldable display having excellent flexibility while improving impact resistance compared to the conventional art can be realized.

[0108] 〔summary〕 [Aspect 1] a housing unit including a hinge member and a first housing and a second housing connected via the hinge member; a flexible display panel including a flexible display layer and a supporting substrate; the support substrate is provided between the flexible display layer and the housing unit; a first portion of the support substrate is fixed to the first housing, a second portion of the support substrate is fixed to the second housing, and the flexible display panel is fixed to the housing unit; a surface of the first housing facing the support substrate and a surface of the second housing facing the support substrate are arranged to be aligned on the same plane, and in a first state in which the flexible display panel is in an unbent state, the housing unit has a flat portion that is flat with respect to the same plane and one or more stepped portions that have a step with respect to the same plane; the support substrate has a third portion between the first portion and the second portion of the support substrate; the third portion of the support substrate includes a first region overlapping the step portion and a second region overlapping the flat portion in the first state, A foldable display, wherein a first ratio of a volume of the openings of the opening group in the first region to a volume of the first region in the first region of the support substrate is lower than a second ratio of a volume of the openings of the opening group in the second region to a volume of the second region in the second region of the support substrate.

[0109] [Aspect 2] The foldable display according to aspect 1, wherein each of the openings in the opening group is an opening that penetrates from a surface of the support substrate facing the flexible display layer to a surface of the support substrate facing the housing unit.

[0110] [Aspect 3] 3. The foldable display of claim 1 or 2, wherein the first ratio is 60% or less.

[0111] Aspect 4 The foldable display of embodiment 1 or 2, wherein the second ratio is greater than 55% and less than or equal to 75%.

[0112] Aspect 5 A part of the second region that is in contact with the first region is divided into a plurality of regions, a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; The foldable display of any one of aspects 1 to 4, wherein in each of the plurality of regions, the ratio of each of the plurality of regions increases as the region becomes farther from the first region, within a range of greater than or equal to the first ratio and less than or equal to the second ratio.

[0113] Aspect 6 a portion of the first portion of the support substrate that is in contact with the first region and fixed to the first housing is divided into a plurality of regions; a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; 6. The foldable display of any one of aspects 1 to 5, wherein in each of the plurality of regions, the ratio of each of the plurality of regions decreases as the region becomes farther from the first region.

[0114] Aspect 7 a portion of the second portion of the support substrate that is in contact with the first region and fixed to the second housing is divided into a plurality of regions; a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; 7. The foldable display of any one of aspects 1 to 6, wherein in each of the plurality of regions, the ratio of each of the plurality of regions decreases as the region becomes farther from the first region.

[0115] Aspect 8 the flat portion is formed by the hinge member, The step portion is a plurality of steps, The foldable display of any one of aspects 1 to 7, wherein the plurality of step portions include a gap between the first housing and the hinge member and a gap between the second housing and the hinge member.

[0116] Aspect 9 9. The foldable display of claim 8, wherein the plurality of step portions further include a recess provided in a portion of the hinge member.

[0117] Aspect 10 An adhesive is formed in the recess, 10. The foldable display of claim 9, wherein a portion of the third portion of the support substrate is fixed to the hinge member by the adhesive.

[0118] Aspect 11 The foldable display of aspect 9 or 10, wherein the recess is provided along a bending center of the flexible display panel.

[0119] Aspect 12 12. The foldable display of claim 8, wherein the plurality of step portions further include a protrusion provided on a part of the hinge member.

[0120] Aspect 13 the housing unit includes the first housing, the second housing, and the hinge member that connects the first housing and the second housing, A foldable display according to any one of aspects 8 to 12, wherein the surface of the first housing facing the support substrate and the surface of the second housing facing the support substrate are arranged to face each other, and in a second state in which the flexible display panel is bent, the flexible display panel is teardrop-shaped.

[0121] Aspect 14 the flat portion is formed by a portion of the first housing other than a portion to which the first portion of the support substrate is fixed and a portion of the second housing other than a portion to which the second portion of the support substrate is fixed, 8. The foldable display of claim 1, wherein the step portion includes a gap between the first housing and the second housing.

[0122] Aspect 15 the housing unit includes the first housing, the second housing, and the hinge member that connects the first housing and the second housing, a region including one end of the support substrate is fixed to a region including one end of the first housing, and a region including the other end of the support substrate is fixed to a region including one end of the second housing, so that the flexible display panel is fixed to the housing unit; the flat portion is formed by a portion of the first housing other than an area including the one end and a portion of the second housing other than an area including the one end, the step portion includes a gap between the first housing and the second housing, The foldable display of any one of aspects 1 to 7, wherein the surface of the first housing facing the support substrate and the surface of the second housing facing the support substrate are arranged to face each other, and in a second state in which the flexible display panel is bent, the flexible display panel is U-shaped.

[0123] Aspect 16 16. The foldable display according to any one of aspects 1 to 15, wherein the support substrate is a metal substrate or a resin substrate.

[0124] Aspect 17 17. The foldable display according to any one of aspects 1 to 16, wherein the thickness of the support substrate is 100 μm or more and 300 μm or less.

[0125] Aspect 18 18. The foldable display of any one of claims 1 to 17, wherein the flexible display panel further includes a cushion layer including one or more resin layers between the flexible display layer and the supporting substrate.

[0126] Aspect 19 the cushion layer includes a first adhesive layer, a first film layer, a second adhesive layer, a second film layer, and a third adhesive layer, in this order from the support substrate side; the first film layer and the second film layer are each a resin layer; 19. The foldable display of claim 18, wherein the first film layer has a higher elastic modulus than the second film layer.

[0127] Aspect 20 the cushion layer includes a first adhesive layer, a first film layer, a second adhesive layer, a second film layer, and a third adhesive layer, in this order from the support substrate side; The first adhesive layer is The shear storage modulus at 25°C is 5.0 x 10 4 Pa or more, 1.0×10 6 Pa or less, 20. The foldable display according to embodiment 18 or 19, wherein the compressive stress measured under conditions of a test speed of 0.5 mm / min and a compressive strain of 40% is 500 KPa or more and 1200 KPa or less.

[0128] Aspect 21 21. The foldable display of any one of claims 1 to 20, wherein the flexible display layer comprises a quantum dot-containing light-emitting layer or an organic light-emitting layer.

[0129] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Furthermore, new technical features can be formed by combining the technical means disclosed in the respective embodiments. [Industrial Applicability]

[0130] The present invention can be used in a foldable display. [Explanation of symbols]

[0131] 1, 1a, 1b Foldable display 2, 2', 2'' Enclosure Unit 2a 1st cabinet 2b Second housing 2h1, 2h2, 2h3 Hinge members 2h2' Hinge member 2h4, 2h5, 2h6 Hinge parts 2P flat part 2d1, 2d2 Step 2d3 recess 2S1, 2S2, 2S3, 2S4 Gap between hinge members 3, 3a, 3b Support board 3d aperture 4 Cushioning layer 5 Flexible display layer 6 Functional Layers 7 Flexible Cover 8, 8a, 8b Flexible display panel 9 4th adhesive layer 10 Touch Panel 11 5th adhesive layer 12 Polarizing plate 13 6th adhesive layer 14 1st adhesive layer 15 First film layer 16 Second adhesive layer 17 Second film layer 18 Third adhesive layer 19 Case cover BR: Third part of the support substrate NBR1 Region including one end of the support substrate (first portion) NBR2 Region including the other end of the support substrate (second portion) WA is the line width of the supporting substrate material between the openings in the Y direction WB Width of the aperture in the Y direction WC: Line width of the supporting substrate material between the openings in the X direction WD Width of opening in X direction PIX, PIX' pixels RSP Red sub-pixel GSP Green sub-pixel BSP Blue subpixel

Claims

1. a housing unit including a hinge member and a first housing and a second housing connected via the hinge member; a flexible display panel including a flexible display layer and a supporting substrate; the support substrate is provided between the flexible display layer and the housing unit; a first portion of the support substrate is fixed to the first housing, a second portion of the support substrate is fixed to the second housing, and the flexible display panel is fixed to the housing unit; a surface of the first housing facing the support substrate and a surface of the second housing facing the support substrate are arranged to be aligned on the same plane, and in a first state in which the flexible display panel is in an unbent state, the housing unit has a flat portion that is flat with respect to the same plane and one or more stepped portions that have a step with respect to the same plane; the support substrate has a third portion between the first portion and the second portion of the support substrate; the third portion of the support substrate includes a first region overlapping the step portion and a second region overlapping the flat portion in the first state, A foldable display, wherein a first ratio of a volume of the openings of the opening group in the first region to a volume of the first region in the first region of the support substrate is lower than a second ratio of a volume of the openings of the opening group in the second region to a volume of the second region in the second region of the support substrate.

2. The foldable display according to claim 1 , wherein each of the openings in the opening group is an opening that penetrates from a surface of the support substrate on the flexible display layer side to a surface of the support substrate on the housing unit side.

3. The foldable display of claim 1 , wherein the first ratio is 60% or less.

4. The foldable display of claim 1 or 2, wherein the second ratio is greater than or equal to 55% and less than or equal to 75%.

5. A part of the second region that is in contact with the first region is divided into a plurality of regions, a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; 5. The foldable display according to claim 1, wherein the ratio of each of the plurality of regions increases in a range from the first ratio to the second ratio as the region becomes farther from the first region.

6. a portion of the first portion of the support substrate that is in contact with the first region and fixed to the first housing is divided into a plurality of regions; a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; The foldable display according to claim 1 , wherein the ratio of each of the plurality of regions decreases as the region becomes farther from the first region.

7. a portion of the second portion of the support substrate that is in contact with the first region and fixed to the second housing is divided into a plurality of regions; a ratio of a volume of the openings in the opening group in each of the plurality of regions to a volume of the each of the plurality of regions is different; The foldable display according to claim 1 , wherein the ratio of each of the plurality of regions decreases as the region becomes farther from the first region.

8. the flat portion is formed by the hinge member, The step portion is a plurality of steps, The foldable display according to claim 1 , wherein the plurality of step portions include a gap between the first housing and the hinge member and a gap between the second housing and the hinge member.

9. The foldable display of claim 8 , wherein the plurality of step portions further include a recess provided in a portion of the hinge member.

10. An adhesive is formed in the recess, The foldable display according to claim 9 , wherein a part of the third portion of the support substrate is fixed to the hinge member by the adhesive.

11. The foldable display according to claim 9 or 10, wherein the recess is provided along a bending center of the flexible display panel.

12. The foldable display according to claim 8 , wherein the plurality of step portions further include a protrusion provided on a part of the hinge member.

13. the housing unit includes the first housing, the second housing, and the hinge member that connects the first housing and the second housing, 13. The foldable display according to claim 8, wherein the first housing has a surface facing the support substrate and the second housing has a surface facing the support substrate, and in a second state in which the flexible display panel is bent, the flexible display panel has a drop shape.

14. the flat portion is formed by a portion of the first housing other than a portion to which the first portion of the support substrate is fixed and a portion of the second housing other than a portion to which the second portion of the support substrate is fixed, The foldable display according to claim 1 , wherein the step portion includes a gap between the first housing and the second housing.

15. the housing unit includes the first housing, the second housing, and the hinge member that connects the first housing and the second housing, a region including one end of the support substrate is fixed to a region including one end of the first housing, and a region including the other end of the support substrate is fixed to a region including one end of the second housing, so that the flexible display panel is fixed to the housing unit; the flat portion is formed by a portion of the first housing other than an area including the one end and a portion of the second housing other than an area including the one end, the step portion includes a gap between the first housing and the second housing, 8. The foldable display according to claim 1, wherein the first housing has a surface facing the support substrate and the second housing has a surface facing the support substrate, and in a second state in which the flexible display panel is bent, the flexible display panel has a U-shape.

16. The foldable display according to claim 1 , wherein the supporting substrate is a metal substrate or a resin substrate.

17. The foldable display according to claim 1 , wherein the thickness of the support substrate is 100 μm or more and 300 μm or less.

18. The foldable display according to claim 1 , wherein the flexible display panel further comprises a cushion layer including one or more resin layers between the flexible display layer and the support substrate.

19. the cushion layer includes a first adhesive layer, a first film layer, a second adhesive layer, a second film layer, and a third adhesive layer, in this order from the support substrate side; the first film layer and the second film layer are each a resin layer; The foldable display of claim 18 , wherein the first film layer has a higher elastic modulus than the second film layer.

20. the cushion layer includes a first adhesive layer, a first film layer, a second adhesive layer, a second film layer, and a third adhesive layer, in this order from the support substrate side; The first adhesive layer is The shear storage modulus at 25°C is 5.0 x 10 ４ Pa or more, 1.0×10 ６ Pa or less, The foldable display according to claim 18 or 19, wherein the compressive stress measured under conditions of a test speed of 0.5 mm / min and a compressive strain of 40% is 500 KPa or more and 1200 KPa or less.

21. The foldable display of claim 1 , wherein the flexible display layer comprises a quantum dot-containing light-emitting layer or an organic light-emitting layer.

Images