JP2020095868A - Display device - Google Patents

Abstract

To realize a display device of such a structure that internal stress due to flexure is mitigated, even if a display panel including a display is used while being bent.SOLUTION: A display device is configured so that a first moment M1, i.e., a bending moment, is generated in a substrate 4 when it is bent, in a state where a display panel 1 having a display 3 is bent and supported by a support part 2, an external-force is applied to the substrate 4 furthermore by imparting film thickness distribution or membrane stress distribution to the constituent of the display 3, and a second moment M2, i.e., a bending moment in the opposite direction to the first moment M1, acts on the substrate 4. With such an arrangement, even in a state where the display panel 1 is bent, bending moments in the substrate 4 are cancelled, and internal stress is mitigated.SELECTED DRAWING: Figure 4

Description

The present invention relates to a display device that includes a display unit having a plurality of pixels each including a self-luminous element and is used in a state where the display unit is bent.

In recent years, the display field has been developed, and there has been proposed a display device having a display unit for displaying an image, and the display unit having a curved shape. An example of this type of display device is that described in Patent Document 1.

The display device described in Patent Document 1 is a display unit in which an insulating layer, a thin film transistor, a protective film, a color filter, an interlayer insulating film, and a white light emitting element are laminated in this order on a flexible plastic substrate via an adhesive. And the display portion can have a curved shape. The white light emitting element is a self-luminous element and is an OLED (abbreviation of Organic Light Emitting Diode).

JP, 2017-22146, A

When the display unit is curved, bending stress is generated inside the plastic substrate.If this display device is mounted with the display unit bent, the bending stress may occur inside the plastic substrate. It will be used as it is.

However, if an external force such as vibration is applied to the display device from the outside while the plastic substrate constituting the display section is still under stress, problems such as cracking of the plastic substrate and accompanying malfunction of the OLED may occur. You can In order to use the display portion in a curved shape and to suppress the above-mentioned problems and improve reliability, it is necessary to relieve the stress caused by bending while the plastic substrate is in a bent state.

The present invention has been made in view of the above points, and provides a display device having a structure in which the stress applied to the display unit by bending is relaxed while being used in a state where the display unit has a curved shape. With the goal.

In order to achieve the above object, the display device according to claim 1 includes a flexible substrate (4), a display unit (3) formed on one surface (4a) of the substrate, and displaying an image. Since the display panel (1) having the above is provided and the substrate has a curved curved surface shape, the display portion is used in a state of following the curved surface shape. The display device further has the following features.

The display unit includes a plurality of pixels each including a self-luminous element (5) and a sealing material (6) that covers the self-luminous element. The self-luminous element is formed on one surface and has a pair of members. A first electrode (51) and a second electrode (54), a functional layer (52) disposed between the first electrode and the second electrode, and a partition wall (53) partitioning the functional layer into a plurality of regions. And have. The bending moment generated in the substrate due to the curved surface of the substrate is defined as a first moment, and at least one of the first electrode, the partition wall, and the sealing material is viewed from a direction normal to one surface of the display unit. The film thickness distribution in the central portion is different from the film thickness in the outer edge portion, and a second moment, which is a bending moment in a direction opposite to the direction of the first moment, is generated in the substrate.

As a result, the substrate has a curved surface shape, and in a situation where the display portion on the substrate is used in a shape that follows the curved surface shape, some of the components of the display portion have a predetermined film thickness distribution, and The bending moment generated in the shaped substrate, that is, the first moment is offset.

Specifically, at least one of the first electrode or the partition wall forming the self-luminous element or the sealing material covering the self-luminous element is a film in the central portion of the display portion when viewed from the direction normal to the one surface of the substrate. The thickness and the film thickness at the outer edge are different. This causes a difference in stress acting on the substrate from at least one of the first electrode, the partition wall, and the sealing material, and the bending moment generated on the substrate by this stress is defined as the second moment. The film thickness distribution of at least one of the first electrode, the partition wall, and the sealing material is adjusted so that the second moment has a direction opposite to the first moment.

As a result, the second moment generated in the substrate is canceled by the component of the display unit or the sealing material, and the first moment generated in the substrate is canceled by the curved surface of the substrate. That is, even when the substrate is bent, the bending moment in the substrate is reduced and the bending stress is reduced. Become.

The display device according to claim 5, comprising a flexible substrate (4), and a display unit (3) formed on one surface (4a) of the substrate and displaying an image (1). Since the substrate has a bent curved surface shape, the display unit is used in a state of following the curved surface shape. The display device further has the following features.

The display unit includes a plurality of pixels each including a self-luminous element (5) and a sealing material (6) that covers the self-luminous element. The self-luminous element is formed on one surface and has a pair of members. A first electrode (51) and a second electrode (54), and a functional layer (52) disposed between the first electrode and the second electrode. The first electrode is formed by the vacuum film forming method, with the bending moment generated in the substrate due to the curved surface of the substrate as the first moment, and the first electrode is displayed when viewed from the direction normal to the one surface. The central portion and the outer edge portion of the portion are formed under different film forming conditions, and a second moment, which is a bending moment in a direction opposite to the direction of the first moment, is generated in the substrate.

As a result, the stress acting on the substrate at the central portion of the display portion is different from the stress acting on the substrate at the outer edge portion of the first electrode, and the second moment due to the stress exerted on the substrate by the first electrode is curved. The display device has a structure for canceling the first moment generated in the substrate. Therefore, the same effect as the display device according to the first aspect can be obtained.

The display device according to claim 6, comprising a flexible substrate (4), and a display unit (3) formed on one surface (4a) of the substrate and displaying an image (1). Since the substrate has a bent curved surface shape, the display unit is used in a state of following the curved surface shape. The display device further has the following features.

The display unit includes a self-luminous element (5) formed on one surface and a sealing material (6) covering the self-luminous element, and the sealing material is viewed from a direction normal to the one surface. A first adhesive part (61) in the shape of a frame surrounding the display part, a second adhesive part (62) filling a part surrounded by the first adhesive part, a first adhesive part and a second adhesive part And a covering material (63) attached to. The bending moment generated in the substrate due to the curved surface of the substrate is defined as the first moment, and the first bonding portion is made of a resin material different from the resin material forming the second bonding portion. The second moment, which is the bending moment in the direction opposite to the direction of, is generated in the substrate.

As a result, the stress acting on the substrate in the central portion of the display portion is different from the stress acting on the substrate outside the outer edge portion of the sealing material, and the second moment due to the stress exerted on the substrate by the sealing material is generated. The display device has a structure that cancels the first moment generated in the curved substrate. Therefore, the same effect as the display device according to the first aspect can be obtained.

The reference numerals in parentheses that are given to the respective components and the like indicate an example of a correspondence relationship between the components and the like and specific components and the like described in the embodiments described later.

It is a figure which shows the display apparatus of 1st Embodiment, (a) is a schematic sectional drawing, (b) is a schematic plan view when it sees from a video display surface side. FIG. 2 is a schematic plan view showing an enlarged partial area of a display unit in FIG. 1( b ). FIG. 3 is a schematic cross-sectional view showing an example of a cross-sectional structure taken along the line III-III indicated by the alternate long and short dash line in FIG. 2. FIG. 3 is a schematic diagram showing a state in which a bending moment generated in a bent display panel and a second moment canceling the bending moment are generated in the display device of FIG. 1. FIG. 6 is a schematic diagram showing a result of calculating a distribution of bending moments generated in a situation where a substrate constituting a display panel is regarded as a simple beam and a uniform load is applied to the substrate. 3A and 3B are sectional views of the display unit for each region, wherein FIG. 7A is a schematic sectional view of a central region of the display unit, and FIG. 7B is a schematic sectional view of an outer edge region of the display unit. It is a schematic sectional drawing which shows an example of the cross-sectional structure in the edge part among the display parts in the display apparatus of 2nd Embodiment. FIG. 13 is a schematic cross-sectional view showing a modified example of the display device of the second embodiment and showing an example of a cross-sectional configuration of a display section. It is a schematic sectional drawing which shows an example of a cross-sectional structure in the edge part among the display parts in the display device of 3rd Embodiment. It is a schematic sectional drawing which shows the display apparatus of 4th Embodiment. FIG. 11 is a schematic diagram showing a state in which a bending moment generated in a bent display panel and second and third moments canceling the bending moment are generated in the display device of FIG. 10. It is a figure which shows the modification of the display apparatus of 4th Embodiment, Comprising: (a) is a schematic sectional drawing, (b) is a schematic plan view seen from the image display surface side. It is a figure concerning other modification of a display of a 4th embodiment, (a) is a schematic sectional view of a display, and (b) is a schematic sectional view of a stress relaxation part.

Embodiments of the present invention will be described below with reference to the drawings. In each of the following embodiments, the same or equivalent portions will be denoted by the same reference numerals for description.

(First embodiment)
The display device of the first embodiment will be described with reference to FIGS. The display device according to the present embodiment can be applied as, for example, a curved display device for in-vehicle use which is attached to an instrument panel of a vehicle such as an automobile, but can also be applied as a curved display device for other uses.

1(a) and 1(b), in order to make the configuration easy to understand, the size and thickness of each component are exaggerated and deformed. In addition, in FIG. 1A, a cross-sectional structure taken along the alternate long and short dash line IA-IA in FIG. 2 and 3, in order to make it easy to understand the arrangement and configuration of each component, a state in which the display unit 3 described later is viewed in a plan view or a cross-sectional view in a state where the display unit 3 is not bent is shown.

As shown in FIG. 1A or FIG. 1B, the display device of the present embodiment includes a display panel 1 including a display unit 3 and a support unit 2 that supports the display panel 1 in a bent state. .. In the display device according to the present embodiment, the surface of the display panel 1 on the display unit 3 side is used as the image display surface 1a, and the display panel 1 is supported by the support unit 2 on the surface opposite to the image display surface 1a. The image display surface 1a is curved so as to project to the opposite side of the support portion 2.

Hereinafter, for simplification of description, the above-mentioned curved state is referred to as “convex”, and the curved state in which the image display surface 1a is projected toward the support portion 2 side is referred to as “concave”.

The display panel 1 includes, for example, as shown in FIG. 3, a flexible substrate 4 and a display unit 3 including a plurality of pixels each having a self-luminous element 5 formed thereon. I will do it. The display panel 1 is configured such that when an external force is applied, the flexible substrate 4 is bent so that the display unit 3 can be used in a curved shape. The display panel 1 includes a thin film transistor (not shown) for driving the self-luminous element 5 and a drive wiring, and is connected to an external drive power source and a video input unit (not shown).

As shown in FIG. 1A, the support portion 2 is a member that supports the display panel 1 in a bent state, and is made of, for example, an arbitrary material such as a resin material. As shown in FIG. 1A, the supporting portion 2 may support the display panel 1 in a bent state with a curved surface having an arbitrary curvature, or may have another shape such as a housing. The shape may be changed appropriately.

As shown in FIG. 2, the display unit 3 is formed by arranging a plurality of self-emissive elements 5 forming pixels, and displays various images by causing the self-emissive elements 5 to emit light. As shown in FIG. 3, the display unit 3 includes a plurality of self-luminous elements 5 formed on the one surface 4 a of the substrate 4, and a sealing material 6 that covers the self-luminous elements 5. In the present embodiment, as shown in FIG. 1, the display unit 3 is used in a state where the image display surface 1a is bent to be convexly curved, that is, in a state where the curved surface shape of the substrate 4 is followed. In the present embodiment, in the display unit 3, a partition wall 53, which will be described later, of the self-luminous element 5 has a predetermined film thickness distribution, and a bending moment that cancels a bending moment generated inside the substrate 4 when the substrate 4 is bent ( Hereinafter, it will be referred to as an “offset moment”). The details will be described later.

The display unit 3 is not limited to the convex curved state, and may be used in a concave curved state or in another curved shape, but depending on the final curved state, The film thickness distribution of the partition wall 53 of the self-luminous element 5 is appropriately changed. In the present embodiment, a case where the image display surface 1a is used in a convex shape will be described.

Further, the display panel 1 may be referred to as an “organic EL (abbreviation of Electro Luminescence) panel” when the self-luminous element 5 is composed of an OLED. Further, since the basic configurations of the organic EL panel and the OLED are publicly known, detailed description of publicly known parts will be omitted in the present specification, and characteristic parts of the present application will be mainly described.

The substrate 4 is a flexible substrate made of, for example, an arbitrary resin material such as polyethylene terephthalate (PET) or polyimide (PI) or an arbitrary inorganic material such as glass. The substrate 4 should just be flexible and is not limited to the above-mentioned materials. On one surface 4a of the substrate 4, as shown in FIG. 3, a self-luminous element 5 is formed.

The self-luminous element 5 is, for example, an OLED, and constitutes a pixel together with a thin film transistor (not shown) or the like. In the present embodiment, the self-luminous element 5 is an OLED, and includes, for example, as shown in FIG. 3, a first electrode 51, a functional layer 52, a partition 53, and a second electrode 54. , And these are covered with the sealing material 6. The self-luminous element 5 may have any of a top emission type, a bottom emission type, and a dual emission type element configuration.

The first electrode 51 is an electrode that forms a pair with the second electrode 54 and serves as an anode or a cathode, and is appropriately selected depending on whether the OLED is a top emission type or a bottom emission type. The first electrode 51 is made of, for example, a transparent conductive material such as indium tin oxide (ITO), a known electrode material such as aluminum (Al), or another known alloy material, and is formed by a vacuum film forming method such as sputtering. It is formed.

The functional layer 52 has, for example, a structure in which a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are stacked from the anode side to the cathode side, and the functional layer 52 is provided between the electrodes 51 and 54. It is configured to emit light when a voltage is applied. The functional layer 52 is not limited to the above configuration, and may have a known configuration for other OLEDs. The hole injecting layer, hole transporting layer, light emitting layer, electron transporting layer and electron injecting layer are each formed of a known material and formed by any method such as wet film formation or vacuum film formation. It

The partition wall 53 is, for example, a grid in a plan view as shown in FIG. 2 and is a wall that partitions the functional layer 52 as shown in FIG. 3, and may be referred to as a “bank”. The partition wall 53 is made of, for example, a photosensitive insulating material, and is formed by a wet film formation method and a photolithography etching method. The first electrode 51, the functional layer 52, and the second electrode 54, which are surrounded by the partition wall 53, form one pixel when viewed from the direction normal to the one surface 4a (hereinafter referred to as “one surface normal direction”). A plurality of pixels are arranged side by side to form the display unit 3. In the present embodiment, the partition walls 53 have a predetermined distribution of thickness (hereinafter referred to as “film thickness”) in the normal direction to one surface in order to generate a canceling moment for relaxing the bending moment of the substrate 4. The details will be described later.

As shown in FIG. 3, the second electrode 54 is an electrode arranged on the opposite side of the first electrode 51 with the functional layer 52 interposed therebetween, and when the first electrode 51 is an anode, it is a cathode, When the first electrode 51 is a cathode, it is an anode. The second electrode 54 is made of, for example, a known electrode material and is formed by an arbitrary vacuum film forming method or the like, like the first electrode 51.

The sealing material 6 is a protective layer for protecting the pixels from moisture and oxygen in the outside air, and for example, moisture such as SiN (silicon nitride), SiON (silicon oxynitride), and Al ₂ O ₃ (alumina). It is made of any material having low oxygen permeability. The sealing material 6 is formed by an arbitrary vacuum film forming method such as CVD (abbreviation of Chemical Vapor Deposition), ALD (abbreviation of Atomic Layer Deposition), and sputtering. In the present embodiment, the sealing material 6 has a structure in which a material having a low transmittance such as moisture and oxygen is laminated on the partition wall 53, the second electrode 54, and the like, but is not limited to this. .. Further, the sealing material 6 may be formed by any wet film formation.

The above is the basic configuration of the display device of the present embodiment.

Next, a thickness design of the partition wall 53 for producing a bending moment of the substrate 4 and a canceling moment for relaxing the bending moment will be described with reference to FIGS. 4 to 6.

First, with reference to FIG. 4, an outline of relaxation of bending stress generated inside the substrate 4 will be described.

In FIG. 4, for convenience, a bending moment generated by bending the substrate 4 is defined as a first moment M1, and the first moment M1 is indicated by a black arrow. Further, in FIG. 4, the bending moment (offset moment) generated in the substrate 4 by the display unit 3, that is, the second moment M2 is indicated by a white arrow, and the magnitude of the moment generated in each part of the substrate 4 is indicated by an arrow for convenience. The size is shown. It should be noted that FIG. 4 merely shows a deformed image in order to make the relationship between the first moment M1 and the second moment M2 easy to understand, which means that a bending moment is generated only at the arrow portion. is not.

Specifically, as shown in FIG. 4, when the substrate 4 is bent, a first moment M1 is generated inside the substrate 4, but the display unit 3 reverses the first moment M1. The second moment M2 in the direction is generated in the substrate 4. As a result, the first moment M1 and the second moment M2 are canceled out, and the internal force generated inside the substrate 4 is reduced, so that the bending stress of the substrate 4 is reduced.

That is, the display unit 3 plays a role of relieving the bending stress of the substrate 4 when the substrate 4 has a curved shape. In order to have the configuration of the display unit 3 that produces such an action, it is necessary to calculate the distribution of the first moment M1 that occurs in the curved surface shape of the substrate 4 when used.

Here, the calculation of the distribution of the first moment M1 generated in the substrate 4 when the substrate 4 is bent will be briefly described with reference to FIG.

In FIG. 5, the substrate 4 is regarded as a simple beam, the bending force by the supporting portion 2 (not shown) is regarded as a uniformly distributed load F (N/m), and the distribution of the first moment M1 generated on the substrate 4 by the uniformly distributed load F is shown. Shows. Further, in FIG. 5, one end of the substrate 4 is a point A, the other end is a point B, an intermediate position between the points A and B is an O point, and a predetermined distance x (m) from the point A An arbitrary point separated by a distance is defined as a point C, and the length between the directions connecting the points A and B is defined as L1(m). Then, in FIG. 5, a curve based on a mathematical formula of a quadratic curve, which will be described later, obtained by calculating the bending moment at the point C, that is, the first moment M1(N·m), with the downward direction of the paper being positive, is broken for convenience. It shows with.

The reaction force against the load F generated at the points A and B is F×L1/2 due to the balance of forces. The first moment M1 generated at the point C is calculated as the sum of the bending moment due to the reaction force at the point A and the bending moment due to the action of the concentrated load by converting the load F into the concentrated load. It is represented by a formula.

M1=-F×xx/2+F×L1/2×x
^{= -F · x 2/2 +} F · L1 · x / 2 ··· (1)
Note that according to the above (1), M1 = -F / 2 {( x-L1 / 2) 2 -L1 2/4} and since the expressed, when x = L1 / 2, i.e. at the point O The first moment M1 becomes maximum, and the first moment M1 at points A and B becomes minimum.

As described above, the distribution of the first moment M1 generated by bending the substrate 4 is represented as a quadratic curve of x, as indicated by a broken line in FIG. Based on the distribution of the first moment M1 obtained by the above calculation, an external force that causes a second moment M2 opposite to the first moment M1 acts on the substrate 4 so that an external force acts on the substrate 4. Among them, the film thickness distribution of the partition wall 53 is appropriately determined.

The bending stress σ of the substrate 4 is based on the strain amount ε of the substrate 4 in a state where the substrate 4 is bent with a predetermined radius of curvature R and the Young's modulus E of the material forming the substrate 4 (Hook's law ( It is also possible to calculate the distribution of bending stress σ by calculating σ=εE). The strain amount ε can be calculated based on the plane size of the substrate 4 by a method such as FEM (abbreviation of Finite Element Method) analysis.

Next, an example of the film thickness distribution of the partition wall 53 will be described with reference to FIGS. 6(a) and 6(b).

In FIGS. 6A and 6B, the components other than the substrate 4, the first electrode 51, the functional layer 52, and the partition wall 53 of the display unit 3 are omitted for clarity. In the following description, the “central region” of the display unit 3 means a predetermined region including the central portion of the region surrounded by the outline of the display unit 3 when viewed in the normal direction to one surface. Further, the “outer edge region” of the display unit 3 means a region outside the central region of the display unit 3 when viewed from the normal direction to one surface, and a predetermined region including the outer contour of the display unit 3. To do.

In the present embodiment, the partition wall 53 has a film thickness of a portion located in the central region of the display unit 3 and a film thickness of a portion located in the outer edge region of the display unit 3 when the display unit 3 is viewed from the normal direction to one surface. The film thickness distributions are different. Specifically, for example, as shown in FIGS. 6A and 6B, the partition wall 53 has a thinner film thickness in the central region of the display unit 3 than in the outer edge region of the display unit 3. It is configured. For example, the thickness of the partition wall 53 is not limited, but is about 1 μm in the central region and about 4 μm in the outer edge region.

The partition wall 53 assumes, for example, a state in which the substrate 4 is bent at a predetermined radius of curvature R (that is, a curved state during use), and the area of the central region and the area of the outer edge region of the display unit 3 in this state. The film thickness is determined according to the ratio. For example, when the area of the central region is 1 and the area of the outer edge region is 2.5, the partition wall 53 has a thickness ratio of 1:2.5 in the central region and the outer edge region.

The central region and the outer edge region of the display unit 3 are appropriately set according to the distribution of the bending moment or bending stress generated inside the substrate 4 when the substrate 4 is bent when used. Then, the film thickness distribution of the partition wall 53 may be designed corresponding to the area ratio of these regions.

Further, the determination of the film thickness ratio of the partition wall 53 described above is performed in a state where the display panel 1 is bent in a convex shape, that is, a state in which the image display surface 1a is bent to be a convex surface (hereinafter referred to as a “convex bent state”). ) Is an example used in. In the state where the display panel 1 is bent in the opposite direction to the convex bent state, that is, when the image display surface 1a is bent so as to be concave, the partition wall 53 has a film thickness in the central region in the above area ratio. The film thickness ratio in the outer edge region is 2.5:1. The display panel 1 is, of course, not limited to use in this bent shape.

As described above, the partition wall 53 has a film thickness distribution corresponding to the radius of curvature R of the substrate 4 in use, so that the force acting on the substrate 4 by the partition wall 53 is distributed.

Specifically, the second moment M2 is generated by applying an external force to the substrate 4 based on the contraction stress inside the partition wall 53 formed by an arbitrary film forming method. When the film thickness of the partition wall 53 increases, the contraction stress inside the partition wall 53 also increases, and the external force acting on the substrate 4 by the partition wall 53 also increases. That is, the larger the thickness of the partition wall 53 in the substrate 4, the larger the second moment M2 generated in the region. Therefore, by providing the partition wall 53 with a film thickness distribution corresponding to the distribution of the first moment M1 of the substrate 4, it is possible to generate the second moment M2 in the substrate 4 that has a distribution that cancels the first moment M1. As a result, even when the substrate 4 is still bent, the internal force inside the substrate 4 is reduced and the internal stress of the substrate 4 is relieved.

It should be noted that the term “relaxation of internal stress” used here means a state in which the bending stress generated in the substrate 4 when the display panel 1 (substrate 4) having a substantially flat plate shape is bent to have a curved surface shape is maintained. However, it means that other external force is applied to the substrate 4 and becomes smaller than the conventional one. Ultimately, it is preferable that the bending stress when the substrate 4 has a curved shape is the same as the bending stress when the substrate 4 has a substantially flat plate shape, but the present invention is not limited to this. .. Further, in order to relieve the internal stress, not only the bending stress of the curved substrate 4 is reduced as a whole, but also the bending stress of the bent portion is reduced when the substrate 4 is locally bent. Including that. The second moment M2 generated by the partition wall 53 can be calculated by, for example, a simulation.

The partition wall 53 having the predetermined film thickness distribution as described above is, for example, by a photolithography etching method, using a photomask having a distribution of the transmittance of ultraviolet rays used for the exposure processing, and irradiating the ultraviolet rays at each position with an irradiation intensity of ultraviolet rays. Can be formed by adjusting. Further, the partition wall 53 is not limited to the above method, but can be formed by performing a plurality of exposure processes using a plurality of photomasks having different patterns for transmitting ultraviolet rays. The thickness of the partition wall 53 may be continuously changed from the central region of the display unit 3 toward the outer edge region or may be changed intermittently, and is appropriately changed according to the curved shape of the substrate 4. Be changed.

According to this embodiment, while the display unit 3 is used in a curved shape, the curved shape causes the first moment M1 generated inside the substrate 4 and the second moment M2 in the opposite direction. The display device has a structure in which the bending moment is reduced. In other words, in the display device of the present embodiment, in the state where the display panel 1 has a planar shape, the second moment M2, which assumes a curved surface shape with a predetermined curvature, acts and has a curved surface shape. Thus, the first moment M1 is reduced. Therefore, while the display unit 3 is used in a curved shape, the internal stress of the substrate 4 is reduced as compared with the conventional one, and the display device has high reliability.

In particular, for in-vehicle applications, it is assumed that an external force such as vehicle vibration acts on the display device, but it is apparent that the internal stress is relaxed even though it is a curved surface, so the vibration is propagated. However, the effect of suppressing defects such as cracking of the substrate 4 is expected. Further, since the internal stress of the substrate 4 in the bent state is relaxed, the stress applied to the display unit 3 is also relaxed, and the effect of suppressing the constituent elements of the display unit 3 from peeling off from the substrate 4 is expected. ..

(Second embodiment)
The display device of the second embodiment will be described with reference to FIG. 7.

In the display device of the present embodiment, the sealing material 6 in the display portion 3 instead of the partition wall 53 has a film thickness distribution in which the film thickness in the central region and the film thickness in the outer edge region are different. This is different from the first embodiment. In the present embodiment, this difference will be mainly described.

In the present embodiment, the sealing material 6 is in the state shown in FIG. 3 in the central region of the display unit 3 and in the state shown in FIG. 7 in the outer edge region of the display unit 6. In other words, the sealing material 6 causes the second moment M2 to occur in the substrate 4 by making the film thickness distribution in the central region smaller than the film thickness in the outer edge region, so that the first moment M1 of the substrate 4 is It cancels out and plays a role of relaxing bending stress. Even with such a configuration, it is possible to generate the second moment M2 similar to that in the example shown in FIG. 4 and relieve the internal stress of the substrate 4 in the bent state.

The sealing material 6 whose film thickness distribution has been adjusted can be formed, for example, by using a mask to cause a film thickness difference in an arbitrary film forming method such as CVD, ALD, or sputtering. The thickness of the sealing material 6 may be changed continuously or intermittently from the central region of the display unit 3 toward the outer edge region, and the sealing member 6 may be changed according to the curved surface shape of the substrate 4. Will be changed accordingly.

According to this embodiment, the same effect as that of the first embodiment can be obtained.

(Modification of the second embodiment)
A modified example of the display device of the second embodiment will be described with reference to FIG. In FIG. 8, in order to make the configuration of the sealing material 6 easy to understand, the plurality of self-luminous elements 5 forming the display unit 3 are shown as one.

In this modification, the configuration of the sealing material 6 is different from that of the second embodiment, and this difference will be mainly described.

In the present modification, the sealing material 6 is, as shown in FIG. 8, a first adhesive portion 61 arranged outside the plurality of self-luminous elements 5 forming the display portion 3 and an inside of the first adhesive portion 61. And a covering material 63 arranged on the second adhesive portion 62 and the second adhesive portion 62.

The first adhesive portion 61 is a frame-shaped member that surrounds the plurality of self-luminous elements 5 that form the display portion 3 when viewed from the normal direction to one surface, and is made of any adhesive resin material. May be referred to as a "dumb agent". The first adhesive portion 61 is a member that applies an external force to the substrate 4 due to the contraction stress inside the first adhesive portion 61 and causes the second adhesive portion 62 to generate the second moment M2.

The second adhesive portion 62 is a member that is disposed inside the first adhesive portion 61 when viewed in the normal direction to one surface and fills the area surrounded by the first adhesive portion 61. The second adhesive portion 62 is made of any adhesive resin material and may be referred to as a “fill agent”. Similar to the first adhesive portion 61, the second adhesive portion 62 plays a role of applying an external force to the substrate 4 due to the contracting stress inside the second adhesive portion 61 to generate the second moment M2.

Since the first adhesive portion 61 and the second adhesive portion 62 generate a distribution in the second moment M2 by causing a difference in contraction stress inside each, the physical properties such as elastic modulus and composition are different. It is made of resin material. Even with such a configuration, it is possible to generate the second moment M2 similar to that in the example shown in FIG. 4 and relieve the internal stress of the substrate 4 in the bent state. The 1st adhesion part 61 and the 2nd adhesion part 62 are applied by arbitrary application methods, such as dispenser application, for example.

As shown in FIG. 8, the covering material 63 is a member that is disposed on the first adhesive portion 61 and the second adhesive portion 62 and covers the plurality of self-luminous elements 5 that form the display unit 3. The covering material 63 has a low moisture and oxygen permeability and is a flexible member that can follow the bending of the base material 4 when the base material 4 is bent, and can be referred to as a “barrier film”. A known barrier film or the like can be adopted as the covering material 63, and the covering material 63 has an arbitrary configuration.

In the display device of the present modification, the force acting on the substrate 4 by the first adhesive portion 61 and the force acting on the substrate 4 by the second adhesive portion 62 are different from each other, so that the second moment M2 is distributed. This is a structure in which the above-mentioned problem occurs, and the same effect as that of the display device of the second embodiment can be obtained.

(Third Embodiment)
A display device of the third embodiment will be described with reference to FIG.

The display device of the present embodiment is configured in such a manner that the first electrode 51 in the display section 3 instead of the partition wall 53 has a film thickness distribution in which the film thickness in the central region and the film thickness in the outer edge region are different. This is different from the first embodiment. In the present embodiment, this difference will be mainly described.

In the present embodiment, the first electrode 51 is in the state shown in FIG. 3 in the central region of the display unit 3 and in the state shown in FIG. 9 in the outer edge region of the display unit 6. That is, the first electrode 51 causes the second moment M2 to be generated in the substrate 4 by making the film thickness distribution in the central region smaller than the film thickness in the outer edge region, so that the first moment M1 of the substrate 4 is It cancels out and plays a role of relaxing bending stress. Even with such a configuration, it is possible to generate the second moment M2 similar to that in the example shown in FIG. 4 and relieve the internal stress of the substrate 4 in the bent state.

The first electrode 51 whose film thickness distribution is adjusted can be formed, for example, by using a mask to cause a film thickness difference in an arbitrary film forming method such as sputtering. The thickness of the first electrode 51 may be continuously changed or may be changed intermittently from the central region of the display unit 3 toward the outer edge region, and the first electrode 51 may be changed in accordance with the curved shape of the substrate 4. Will be changed accordingly.

According to this embodiment, the same effect as that of the first embodiment can be obtained.

(Modification of Third Embodiment)
Next, a modified example of the display device of the third embodiment will be described. In this modification, the components of the display unit 3 have a uniform film thickness in all regions, and the first electrode 51 has a state in which the internal stress is different between the central region and the outer edge region of the display unit 3. It is different from the third embodiment in that In this modification, this difference will be mainly described.

In this modification, the first electrode 51 is formed by, for example, a magnetron sputtering method, and is formed under different film forming conditions in the central region and the outer edge region of the display unit 3. This causes a difference between the internal stress in the central region of the display unit 3 and the internal stress in the outer edge region of the first electrode 51, so that the second moment M2 having a distribution corresponding to the first moment M1 is generated. This is because of the configuration that causes

Specifically, for example, as in the method described in International Publication No. WO 2014/020788, a mask is used in the magnetron sputtering method to give a distribution to the film formation power density which is the film formation power per unit target area. .. More specifically, the film formation power density in the outer edge region of the display unit 3 is adjusted to be higher than the film formation power density in the central region. As a result, the film stress in the central region of the first electrode 51 where the film forming power density is relatively low becomes smaller than the film stress in the outer edge region where the film forming power density is relatively high. As a result, the external force generated on the substrate 4 is distributed between the portion of the first electrode 51 where the film stress is small and the portion where the film stress is large, and the second moment 2 is also distributed.

That is, by providing the film stress of the first electrode 51 with a distribution corresponding to the first moment M1, even if the substrate 4 is bent, the second moment M2 causes the film stress to have a distribution corresponding to the first moment M1. The first moment M1 is canceled and the bending stress of the substrate 4 is relaxed.

Also according to this modification, the same effect as that of the third embodiment can be obtained.

(Fourth Embodiment)
A display device according to the fourth embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 shows a sectional configuration corresponding to FIG. 1A in the first embodiment. In FIG. 11, in order to distinguish a third moment M3 and a second moment M2, which will be described later, for convenience, the second moment M2 is indicated by a dashed outline arrow, and the third moment M3 is indicated by a solid outline arrow. ing. 11, the first moment M1 is indicated by a black arrow and the magnitude of the moment generated for each part of the substrate 4 is indicated by the size of the arrow for convenience, as in FIG. It does not mean that the bending moment occurs only in the indicated portion.

The display device according to the present embodiment further includes the stress relaxation portion 7, and the stress relaxation portion 7 is configured to generate the third moment M3 that cancels the bending moment M1 of the substrate 4. Be different. In the present embodiment, this difference will be mainly described.

As shown in FIG. 10, the stress relieving portion 7 is a member that is arranged in contact with the display panel 1 and is used to relieve the internal stress generated in the substrate 4 when the display portion 3 has a curved shape.

Specifically, as shown in FIG. 11, when the display panel 1 is bent by the support portion 2, a first moment M1 is generated inside the substrate 4. As shown in FIG. 11, the stress relaxation section 7 causes the substrate 4 to generate a third moment M3 that is opposite to the first moment M1. As a result, the first moment M1, the second moment M2, and the third moment M3 cancel each other out, and the internal force generated inside the substrate 4 decreases, so that the bending stress of the substrate 4 decreases. That is, in the display panel 1 bent by the support part 2, the stress relaxation part 7 causes the display part 3 to generate a bending force in the direction opposite to the bending force of the support part 2 for bending the display part 3, thereby causing the display part 3 to display. It is a member that relieves the bending stress that acts.

In the present embodiment, the stress relaxation portion 7 is configured to have an optical resin layer 71 made of an arbitrary optical resin such as an acrylic resin material, and as shown in FIG. 11, the image display surface 1a side. It is placed in contact with. Like the film thickness distribution of the constituent elements of the display unit 3, the optical resin layer 71 has a convex portion (in the cross-sectional view, as shown in FIG. In this example, the thickness in the vicinity of the central portion) is smaller than the thickness in the end portion side of the image display surface 1a.

The optical resin layer 71 is OCA (abbreviation of Optical Clear Adhesive) or OCR (abbreviation of Optical Clear Resin), and a transparent panel (not shown) such as a clear panel is attached to the surface opposite to the image display surface 1a. May be. Further, the optical resin layer 71 is not limited to the thickness distribution described above, and the thickness distribution may be appropriately changed according to the bent shape of the display panel 1.

According to the present embodiment, while the display unit 3 is used in a bent state, in addition to the second moment M2 due to the display unit 3, the third moment M3 due to the stress relieving unit 7 is further generated, and the third moment M3 due to the substrate 4 is generated. The display device has a structure that cancels one moment M1. Therefore, in addition to the first embodiment described above, a display device in which the bending stress of the substrate 4 is further relaxed is obtained.

(First Modification of Fourth Embodiment)
A first modified example of the display device of the fourth embodiment will be described with reference to FIGS. 12(a) and 12(b). In FIG. 12A, the outline of an opening 722a, which will be described later, that exists in another cross section is indicated by a broken line. In FIG. 12B, the outer contour of the display panel 1 which is hidden by the housing component 72 described later and cannot be seen from the front is shown by a broken line.

As shown in FIG. 12A, the display device of the present modified example is different from the fourth embodiment in that the stress relaxation section 7 is composed of a housing component 72. In this modification, this difference will be mainly described.

The housing component 72 is a member that is attached to the display panel 1 and holds the display panel 1 in a bent state, while applying an external force acting on the display panel 1 by the third moment M3, for example, the bottom portion 721. And a lid portion 722 are assembled. For example, as shown in FIG. 12A, the housing component 72 is brought into contact with the image display surface 1a when the display panel 1 is bent so that the image display surface 1a is curved in a convex shape. , A force is applied to the display panel 1 in the direction opposite to the bending force applied by the support portion 2. For example, as shown in FIG. 12B, the housing component 72 has an opening 722 a formed in the lid 722 so that the display unit 3 is exposed even when the display panel 1 is housed.

The housing part 72 is made of an arbitrary material such as a resin material. If the housing part 72 is made of a transparent material that transmits light, the opening 722a may not be formed. Further, the housing component 72 may be a member that also serves as the support portion 2 by, for example, forming a protrusion corresponding to the support portion 2. In this case, the support part 2 becomes unnecessary. Furthermore, although the case component 72 has been described with respect to the example including the bottom portion 721 and the lid portion 722, the case component 72 is not limited to this, and may be a single member in which these are integrated, It may be composed of three or more parts.

Similarly to the example shown in FIG. 11, the housing component 72 is configured to press the image display surface 1a so that the substrate 4 has the third moment M3 opposite to the first moment M1 generated by the support portion 2. ing. For example, the thickness of the portion of the lid portion 722 that is disposed above the convex portion (center portion side) of the display panel 1 in cross section is greater than the thickness of the portion that is disposed above the end portion side of the display panel 1. The display panel 1 is configured to be pressed more strongly than the convex portion on the end side thereof.

Note that the housing component 72 may be configured so that the force generated by the third moment M3 acts on the display panel 1, and as shown in FIG. Instead, the display panel 1 may be partially abutted. The housing component 72 may have a configuration in which a plurality of columnar portions are provided on the surface of the lid portion 722 on the display panel 1 side at predetermined intervals, and these columnar portions abut the display panel 1. In this case, the pressing force can be changed by changing the height of the columnar portion for each place. In this way, the shape and structure of the housing part 72 may be changed as appropriate.

In the display device of the present modification, for example, the display panel 1, the support portion 2, and the housing component 72 are prepared, and after the display panel 1 is bent by the support portion 2, the display device is housed in the housing component 72. Can be manufactured. In the case of the housing part 72 which also serves as the support portion 2, the display panel 1 and the housing part 72 may be prepared and then housed in the housing part 72.

This modification also provides a display device that achieves the same effects as those of the fourth embodiment.

(Second Modification of Fourth Embodiment)
A second modification of the display device of the fourth embodiment will be described with reference to FIGS. 13(a) and 13(b). In FIG. 13B, a color filter 73 as a stress relaxation section 7 described later shows an enlarged part of a portion in contact with the display panel 1, but a part of the color filter 73 is shown for easy viewing. The components of are omitted.

As shown in FIG. 13A, the display device of this modification is different from the fourth embodiment in that the stress relaxation section 7 is a color filter 73. In the present embodiment, this difference will be mainly described.

The color filter 73 has the same configuration as a known color filter except that the thickness of the photo spacer 77, which will be described later, has a distribution, and therefore will be briefly described in this specification.

The color filter 73 is attached to the image display surface 1a of the display panel 1, as shown in FIG. The color filter 73 includes, for example, as shown in FIG. 13B, a base material 74, a black matrix 75, a color resist 76, a photo spacer 77, and a transparent conductive film 78 formed on the surface of the base material 74. To have. The base material 74 is made of a resin material, for example, and is a flexible transparent member. The black matrix 75 is made of an arbitrary material that does not transmit light, partitions the color resist 76, and prevents color mixing of light. A plurality of types of color resists 76 are arranged and are members that transmit light of different wavelengths such as red, green, and blue. The photo spacer 77 is a columnar member for adjusting the gap between the color resist 76 and the display unit 3, and is made of, for example, a photosensitive resin material. The transparent conductive film 68 is a film that covers the color resist 76, and is made of, for example, ITO (indium tin oxide). The color filter 73 is manufactured by a known method.

When the color filter 73 is used as the stress relaxation section 7, the self-luminous element 5 is a white light emitting element.

In this modification, the thickness of the photo spacer 77 is changed according to the contact position with the display panel 1. For example, as shown in FIG. 13A, a case where the display panel 1 is bent so that the image display surface 1a is curved in a convex shape will be described. In this case, as shown in FIG. 13A, if the thickness of the photo spacer 77 that contacts the end of the display panel 1 is L2, and the thickness of the photo spacer 77 that contacts the convex portion of the display panel 1 is L3. , L2>L3. In other words, the photo spacer 77 has a thickness distribution corresponding to the contact portion with the display panel 1.

By attaching the color filter 73 having such a configuration to the display panel 1, the distribution of the force pressing the display panel 1 can be appropriately adjusted. Even in such a case, similarly to the fourth embodiment, the third moment M3 in the opposite direction to the first moment M1 by the support portion 2 can be generated. Therefore, by attaching the color filter 73 to the display panel 1, it is possible to reduce the bending moment and eventually the bending stress generated inside the display panel 1 while having the bent curved surface shape.

This modification also provides a display device that achieves the same effects as those of the fourth embodiment.

(Other embodiments)
The display device shown in each of the above-described embodiments is an example of the display device of the present invention, and is not limited to each of the above-described embodiments. Can be changed appropriately.

(1) In each of the above-described embodiments, an example in which the display panel 1 is used in a state of being bent in a convex shape has been described. However, the display panel 1 is bent in a state of being bent in a concave shape or another curved shape. It goes without saying that it may be used in the state in which it is used. In this case, the film thickness distribution and film forming conditions of the display unit 3 and the stress relaxation unit 7 may be appropriately changed according to the bent state of the substrate 4 when the display panel 1 is used.

For example, when the display panel 1 is used in a state of being bent in a concave shape, at least one of the first electrode 51, the partition 53, and the sealing material 6 has a film thickness in the central region of the display unit 3 that is the outer edge region. It suffices that the film thickness distribution is thicker than the film thickness in. More specifically, this film thickness distribution is determined corresponding to the first moment M1 due to the bending of the substrate 4 when the display panel 1 is used. The basic design when the stress relaxation section 7 is used is the same as above. Further, when the film forming conditions of the first electrode 51 are changed as in the modification of the third embodiment, the film stress of the first electrode 51 is changed based on the assumed distribution of the first moment M1. The film forming conditions may be changed in consideration of the distribution.

In any case, the display unit 3 and the stress relaxation unit 7 generate a second moment M2 or a third moment M3 opposite to the first moment M1 generated inside the substrate 4 when the substrate 4 is bent, in the substrate 4. It may be configured to allow it.

(2) In the fourth embodiment and its modification, the example in which the stress relaxation section 7 is further added to the display device of the first embodiment has been described. However, the structure is not limited to the display device of the first embodiment, and the stress relaxation section 7 may be added to the second embodiment and the third embodiment described above. Further, the display devices of the first to fourth embodiments described above may be freely combined.

(3) In the above-described first embodiment, the example in which the support portion 2 is arranged to abut the display panel 1 on the surface opposite to the image display surface 1a has been described, but the present invention is not limited to this, and the image display surface 1a is not limited to this. May be arranged to abut. This also applies to the embodiments other than the first embodiment described above.

(4) In the first to third embodiments described above, the example in which the second moment M2 is generated by adjusting the film thickness distribution of one of the first electrode 51, the partition wall 53, and the sealing material 6 has been described. .. However, it is not limited to the above example as long as it is a part that does not affect the brightness and chromaticity when the self-luminous element 5 emits light. For example, other components such as the second electrode 54 in the case where the self-luminous element 5 is a bottom emission type may be a display device having a configuration in which the film thickness distribution is adjusted.

DESCRIPTION OF SYMBOLS 1 display panel 2 support part 3 display part 4 substrate 5 self-luminous element 51 first electrode 53 partition wall 6 sealing material 7 stress relaxation part

Claims (11)

A display panel (1) having a flexible substrate (4) and a display unit (3) formed on one surface (4a) of the substrate and displaying an image is provided, and the substrate is bent. By being a curved shape, the display unit is used in a state in which the display unit has a shape following the curved shape,
The display section includes a plurality of pixels each including a self-luminous element (5), and a sealing material (6) covering the self-luminous element,
The self-luminous element is formed on the one surface, and has a pair of first electrode (51) and second electrode (54), and a functional layer disposed between the first electrode and the second electrode. (52) and a partition wall (53) partitioning the functional layer into a plurality of regions,
A bending moment generated in the substrate when the substrate has the curved surface shape is defined as a first moment,
At least one of the first electrode, the partition wall, and the encapsulant has a film thickness that is different from the film thickness in the central portion and the outer edge portion of the display portion when viewed from the direction normal to the one surface. A display device having a distribution, and a second moment, which is a bending moment in a direction opposite to the direction of the first moment, is generated in the substrate. The display device according to claim 1, wherein the partition walls have a film thickness distribution in which the film thickness at the central portion and the film thickness at the outer edge portion are different when viewed from the normal direction. The display device according to claim 1, wherein the sealing material has a film thickness distribution in which the film thickness at the central portion and the film thickness at the outer edge portion are different when viewed from the normal direction. The display device according to claim 1, wherein the first electrode has a film thickness distribution in which a film thickness at the central portion and a film thickness at the outer edge portion are different from each other when viewed from the normal direction. A display panel (1) having a flexible substrate (4) and a display unit (3) formed on one surface (4a) of the substrate and displaying an image is provided, and the substrate is bent. By being a curved shape, the display unit is used in a state in which the display unit has a shape following the curved shape,
The display section includes a plurality of pixels each including a self-luminous element (5), and a sealing material (6) covering the self-luminous element,
The self-luminous element is formed on the one surface, and has a pair of first electrode (51) and second electrode (54), and a functional layer disposed between the first electrode and the second electrode. (52) and having,
A bending moment generated in the substrate when the substrate has the curved surface shape is defined as a first moment,
The first electrode is formed by a vacuum film forming method, and when viewed from a direction normal to the one surface, a portion in the central portion and a portion in the outer edge portion of the display portion are formed under different film forming conditions. A display device, which is formed so that a second moment, which is a bending moment in a direction opposite to the direction of the first moment, is generated in the substrate. A display panel (1) having a flexible substrate (4) and a display unit (3) formed on one surface (4a) of the substrate and displaying an image is provided, and the substrate is bent. By being a curved shape, the display unit is used in a state in which the display unit has a shape following the curved shape,
The display section includes a self-luminous element (5) formed on the one surface, and a sealing material (6) covering the self-luminous element,
The encapsulating material has a frame-shaped first adhesive portion (61) surrounding the plurality of self-luminous elements forming the display portion when viewed from a direction normal to the one surface, and the first adhesive portion. A second adhesive part (62) for filling a portion surrounded by and a covering material (63) attached to the first adhesive part and the second adhesive part,
A bending moment generated in the substrate when the substrate has the curved surface shape is defined as a first moment,
Since the first adhesive portion is made of a resin material different from the resin material forming the second adhesive portion, a second moment, which is a bending moment in a direction opposite to the direction of the first moment, is generated in the substrate. A display device configured. Further comprising a stress relaxation portion (7) arranged in contact with the display panel,
7. The stress relieving portion is in contact with the substrate and applies an external force to the substrate to generate a third moment, which is a bending moment in the same direction as the second moment, on the substrate. The display device according to any one of claims. In the display unit, the image display surface is bent in a convex shape, with the surface of the display panel on the display unit side serving as the image display surface (1a).
The stress relaxation portion has an optical resin layer (71) arranged in contact with the display surface side,
In the cross-sectional view, the optical resin layer has a thickness of a portion arranged on a central portion of the display surface bent in a convex shape, from a thickness of a portion arranged on an end portion of the display surface. The display device according to claim 7, which is also thin. In the display unit, the image display surface is bent in a concave shape, with the surface on the display unit side of the display panel serving as the image display surface (1a).
The stress relaxation portion has an optical resin layer (71) arranged in contact with the display surface side,
The optical resin layer has a thickness of a portion arranged on the central portion of the display surface bent in a concave shape as compared with a thickness of a portion arranged on an end portion of the display surface in a sectional view. The display device according to claim 7, which is thick. The stress relaxation section is a housing part (72),
8. The cross-sectional view causes the casing component to exert a bending force on the display panel in a direction of returning the curved display portion of the display panel to the planar shape before being bent. Display device according to. The surface of the display panel on the side of the display unit is used as a video display surface (1a),
The stress relaxation section is a color filter (73) attached to the image display surface side,
The color filter is formed on the base material (74), a plurality of color resists (75) having different wavelengths of transmitted light, a black matrix (76) partitioning the plurality of color resists, and the black matrix. And a plurality of photo spacers (77)
A plurality of the photo spacers, the color filter is attached to the display panel to contact the display surface side to press the display panel,
Of the plurality of the photo spacers, the thickness of the photo spacer disposed on the center side of the display unit is the photo spacer disposed on the end side of the display unit when viewed from the direction normal to the image display surface. The display device according to claim 7, which is thinner than the thickness of the display device.

Images