CN111640375B

CN111640375B - Flexible display device

Info

Publication number: CN111640375B
Application number: CN202010634033.7A
Authority: CN
Inventors: 黄子硕; 赖炎晖; 柯聪盈; 洪仕馨
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2019-07-24
Filing date: 2020-07-02
Publication date: 2022-03-08
Anticipated expiration: 2040-07-02
Also published as: CN114187841A; CN111640375A; CN114187841B

Abstract

A flexible display device includes a display panel and a reinforcing structure. The reinforcing structure is arranged below the display panel. The reinforcing structure comprises a first supporting plate, a second supporting plate and an adhesion layer arranged between the first supporting plate and the second supporting plate. The first support plate has a Young's modulus E₁，100GPa≤E₁Less than or equal to 250 GPa. The second support plate has a Young's modulus E₂，100GPa≤E₂≤250GPa。

Description

Flexible display device

Technical Field

The present invention relates to a display device, and more particularly, to a flexible display device.

Background

In recent years, with the rise of foldable electronic devices (e.g., foldable mobile phones), the development of flexible display panels has been highlighted again. In general, in order to support a flexible substrate in a flexible display panel and provide sufficient stiffness (rigidity), a plate with good stiffness and ductility is disposed under the flexible display panel. However, after the flexible display panel is repeatedly bent for many times, the plate of the flexible display panel may be broken (crack) at the bending central axis, which may cause the failure of the flexible display panel.

Disclosure of Invention

The invention provides a flexible display device with good performance.

The flexible display device of an embodiment of the invention includes a display panel and a reinforcing structure. The reinforcing structure is arranged below the display panel. The reinforcing structure comprises a first supporting plate, a second supporting plate and an adhesion layer arranged between the first supporting plate and the second supporting plate. The side wall of the first supporting plate is provided with a first bright band and a first dark band, the flexible display device is used for protruding towards a direction, and the first dark band and the first bright band are sequentially arranged along the direction.

The flexible display device of an embodiment of the invention includes a display panel and a reinforcing structure. The reinforcing structure is arranged below the display panel. The reinforcing structure comprises a first supporting plate, a second supporting plate and an adhesion layer arranged between the first supporting plate and the second supporting plate. The first support plate has a Young's modulus E₁，100GPa≤E₁Less than or equal to 250 GPa. The second support plate has a Young's modulus E₂，100GPa≤E₂≤250GPa。

Drawings

Fig. 1 is a side view of an unbent flexible display device 10 according to an embodiment of the invention.

Fig. 2 is a schematic side view of a bent flexible display device 10 according to an embodiment of the invention.

Fig. 3 is a side view of a reinforcing structure 200 according to an embodiment of the invention.

Fig. 4 shows the

bright bands

213a, 223a and the

dark bands

213b, 223b of the

sidewalls

213, 223 of the supporting

plates

210, 220 according to an embodiment of the present invention, as observed by an optical microscope.

Fig. 5 is a side view of an unbent flexible display device 10A according to an embodiment of the invention.

Fig. 6 is a side view of a bent flexible display device 10A according to an embodiment of the invention.

Fig. 7 is a side view of a reinforcing structure 200A according to an embodiment of the invention.

List of reference numerals

10. 10A: flexible display device

100: display panel

100 a: display surface

200. 200A: reinforcing structure

210. 220, and (2) a step of: supporting plate

211. 212, 221, 222: surface of

213. 223: side wall

213a, 223 a: bright band

213b, 223 b: dark belt

230: adhesive layer

300: optical cement

400: light-transmitting cover plate

500: optical cement

d1, d 2: direction of rotation

H1, H2: thickness of

L1, L2: length of

S1, S2: neutral plane

Detailed Description

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers (or numbers) are used in the drawings and the description to refer to the same or like parts.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected" may refer to physical and/or electrical connections. Further, "electrically connected" or "coupled" may mean that there are additional elements between the elements.

As used herein, "about", "approximately", or "substantially" includes the stated value and the average value within an acceptable range of deviation of the specified value as determined by one of ordinary skill in the art, taking into account the measurement in question and the specified amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" may mean within one or more standard deviations of the stated value, or within ± 30%, ± 20%, ± 10%, ± 5%. Further, as used herein, "about", "approximately" or "substantially" may be selected based on optical properties, etch properties, or other properties, with a more acceptable range of deviation or standard deviation, and not all properties may be applied with one standard deviation.

Unless defined otherwise, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present invention and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Referring to fig. 1, 2 and 3, the flexible display device 10 includes a display panel 100 and a reinforcing structure 200 disposed under the display panel 100. In the embodiment, the flexible display device 10 may further include an optical adhesive 300, the optical adhesive 300 is disposed between the display panel 100 and the reinforcing structure 200, and the display panel 100 and the reinforcing structure 200 may be connected to each other by the optical adhesive 300, but the invention is not limited thereto.

In the present embodiment, the flexible display device 10 may further include a light-transmitting Cover (Cover)400 disposed on the display surface 100a of the display panel 100. In the embodiment, the flexible display device 10 further includes an optical adhesive 500, the optical adhesive 500 is disposed between the transparent cover 400 and the display panel 100, and the transparent cover 400 and the display panel 100 can be connected to each other by the optical adhesive 500, but the invention is not limited thereto.

For example, in the present embodiment, the display panel 100 is, for example, an organic light emitting diode display panel (OLED display panel), and includes a flexible substrate (not shown), a driving circuit layer (not shown) disposed on the flexible substrate, and a plurality of organic light emitting patterns (not shown) electrically connected to the driving circuit layer. However, the present invention is not limited thereto, and the display panel 100 may also be other kinds of display panels, such as but not limited to: a micro light emitting diode display panel (μ LED display panel). In addition, the present invention is not limited to the display panel 100 having only the display function; in another embodiment not shown, the display panel 100 can also have both display and touch functions.

The reinforcing structure 200 includes a plurality of supporting

plates

210 and 220 and an adhesive layer 230, wherein the adhesive layer 230 is disposed between the plurality of supporting

plates

210 and 220. The plurality of

support plates

210, 220 are connected to each other by an adhesive layer 230. For example, in the embodiment, the adhesion layer 230 is, for example, an Optical Clear Adhesive (OCA), but the invention is not limited thereto.

In the present embodiment, based on the consideration of the fitting tolerance, the area of one of the plurality of supporting

plates

210, 220 may be selectively larger than that of the other one. For example, in the embodiment, the area of the supporting plate 210 close to the display panel 100 may be larger than the area of the supporting plate 220 far from the display panel 100, but the invention is not limited thereto. However, in another embodiment not shown, the area of the supporting plate 220 far away from the display panel 100 may be larger than the area of the supporting plate 210 near the display panel 100.

The reinforcing structure 200 is used to support the relatively soft display panel 100, so that the flexible display device 10 has sufficient stiffness and bending resistance. To balance stiffness and bendability of the entire flexible display device 10, the young's modulus E of the supporting plate 210 of the reinforcing structure 200₁And the Young's modulus E of the supporting plate 220 of the reinforcing structure 200₂Preferably falls within an appropriate range. For example, in the present embodiment, E is 100GPa ≦ E₁Not more than 250GPa and not more than 100GPa not more than E₂≤250GPa。

The material of the supporting

plates

210 and 220 is preferably selected to have high ductility and high stiffness. For example, in the present embodiment, the supporting

plates

210 and 220 are made of stainless steel, for example. However, the invention is not limited thereto, and in other embodiments, the supporting

plates

210 and 220 may be made of other metal materials. For example, the following formula (1) can be used to evaluate whether other metal materials are suitable,

in the formula (1), E₁Is the Young's modulus, L, of the support plate 210₁Refers to the length, H, of the side wall 213 of the support plate 210₁Refers to the thickness of the support plate 210 (i.e., the height of the side wall 213), E₂Is the Young's modulus, L, of the supporting plate 220₂Refers to the length of the side wall 223 of the support plate 220, and H₂Refers to the thickness of the support plate 220 (i.e., the height of the side walls 223).

It is worth mentioning that, since the reinforcing structure 200 is composed of a plurality of supporting

plates

210 and 220 and the adhesive layer 230 sandwiched therebetween, the thickness H of each supporting

plate

210 and 220 of the reinforcing structure 200₁、H₂Can be thinner. As a result, the distances between the

surfaces

212 and 222 of the supporting

plates

210 and 220 and the neutral surfaces S1 and S2 of the supporting

plates

210 and 220 are short, and the stress applied to the

surfaces

212 and 222 of the supporting

plates

210 and 220 is small, so that the reinforcing structure 200 is not easily broken by repeated bending. Furthermore, the thickness H of each

support plate

210, 220 due to the reinforcing structure 200₁、H₂Since the supporting

plates

210 and 220 are thin, the supporting

plates

210 and 220 are not easily creased, which helps to reduce the bending radius of the flexible display device 10.

Referring to fig. 1, 2 and 3, the supporting plate 220, the adhesive layer 230, the supporting plate 210 and the display panel 100 are sequentially stacked in a direction d 1. In the present embodiment, the flexible display device 10 is protruded in a direction d2 opposite to the direction d 1. When the flexible display device 10 protrudes in the direction d2, the display surface 100a of the display panel 100 is recessed inward. That is, the flexible display device 10 of the present embodiment is mainly used for inner folding.

In the present embodiment, the supporting

plates

210 and 220 are sequentially arranged along the direction d2 (i.e. the protruding direction of the flexible display device 10), and the thickness H of the supporting plate 220₂Is less than the thickness H of the support plate 210₁. That is, the thickness H of the supporting plate 220 subjected to a large stress₂The thickness H of the support plate 210 that is relatively less stressed₁Is thin. Therefore, the distance between the surface 222 of the supporting plate 220 and the neutral plane S2 is shorter, and the stress on the surface 222 of the supporting plate 220 is further reduced, thereby further reducingThe probability of breakage of the supporting plate 220 due to repeated bending is low.

The following table shows various thicknesses H of the

support plates

210, 220 of the reinforcement structure 200 according to an embodiment of the present invention₁、H₂And the maximum principal stress to which the reinforcing structure 200 is subjected.

	Condition one	Condition two	Condition three	Condition four	Condition five
						Thickness H₁(μm)	15	20	22.5	25	30
Thickness H₂(μm)	25	20	27.5	15	10
						Maximum principal stress (MPa)	766	663	616	580	684

[ TABLE ] A

The flexible display device (not shown) of the first comparative example is similar to the flexible display device of the present embodiment, and the difference between the flexible display device and the flexible display device is only that: the reinforcing structure of the flexible display device of the first comparative example is a supporting plate without the adhesive layer 230, and the thickness of the supporting plate of the reinforcing structure of the flexible display device of the first comparative example is equal to the thickness H of the supporting

plates

210 and 220 of the reinforcing structure 200 of the flexible display device 10 of the present embodiment₁、H₂And (4) summing. The thickness of the supporting plate of the reinforcing structure of the flexible display device of the first comparative example is 40 μm, and the maximum principal stress to which the reinforcing structure of the flexible display device of the first comparative example is subjected is 1045 MPa. The maximum principal stresses of the flexible display device 10 under the conditions of one to five in the embodiment are 776MPa, 663MPa, 616MPa, 580MPa and 684MPa, respectively; the maximum principal stress of the flexible display device 10 of the present embodiment is significantly lower than the maximum principal stress 1045MPa received by the first comparative example. Furthermore, it can be seen from the above table that, in the present embodiment, the thickness ratio (H) of the supporting

plates

210 and 220₁/H₂) To satisfy the condition that (H) is more than or equal to 1₁/H₂) Less than or equal to 3, preferably, but the present invention is not limited thereto.

The flexible display device (not shown) of the second comparative example is similar to the flexible display device 10 of the present embodiment, and the flexible display device (not shown) of the second comparative example and the flexible display device 10 of the present embodiment have the same total thickness, and the difference between the two is only: the reinforcing structure of the flexible display device of the second comparative example is a supporting plate without an adhesive layer 230, and the thickness of the supporting plate of the reinforcing structure of the flexible display device of the second comparative example is equal to the reinforcing structure of the flexible display device 10 of the present embodiment200 of

support plates

210, 220 has a thickness H₁、H₂In addition, the thickness of the optical adhesive 300 of the reinforcing structure of the flexible display device of the second comparative example is equal to the sum of the thickness of the optical adhesive 300 of the flexible display device 10 of the present embodiment and the thickness of the adhesive layer 230. According to a simulation result, the maximum stress of the flexible display device of the second comparative example is 1182MPa, and the maximum stress of the flexible display device of the present embodiment is 681 MPa. That is, compared to the second comparative example, in the present embodiment, even though the actual adhesive layer 300 is thinner, the stress applied to the reinforcing structure 200 with the plurality of supporting

plates

210 and 200 is still lower than the stress applied to the reinforcing structure of the second comparative example.

Fig. 4 shows the

bright bands

213a, 223a and the

dark bands

213b, 223b of the

sidewalls

213, 223 of the supporting

plates

Referring to fig. 1, 3 and 4, the supporting plate 210 has a surface 211 facing the display panel 100, a surface 212 facing away from the display panel 100, and a sidewall 213 connected between the surface 211 and the surface 212; the support plate 220 has a surface 221 facing the display panel 100, a surface 222 facing away from the display panel 100, and a sidewall 223 connected between the surface 221 and the surface 222. In the present embodiment, a mother plate may be stamped (punch) with a cutter to form the

sidewalls

213, 223 of the plurality of

support plates

210, 220. On the

side walls

213, 223 of the

support plates

210, 220, it can be observed: near the lower knife, the

sidewalls

213, 223 have

bright bands

213a, 223 a; away from the lower knife, the

side walls

213, 223 have

dark bands

213b, 223 b. The

bright bands

213a, 223a are formed when the cutter presses the mother plate, and the

dark bands

213b, 213b are formed when the

support plate

210, 220 is disconnected from the mother plate, so that the roughness of the

bright bands

213a, 223a is smaller than that of the

dark bands

213b, 213b (or, the roughness of the

dark bands

213b, 213b is larger than that of the

bright bands

213a, 223 a), and the

bright bands

213a, 223a appear brighter than the

dark bands

213b, 213 b.

Referring to fig. 1, 2 and 3, the supporting plate 220, the adhesive layer 230, the supporting plate 210 and the display panel 100 are sequentially stacked in a direction d 1. In the present embodiment, the flexible display device 10 is mostly used to be protruded toward a direction d2 opposite to the direction d 1. When the flexible display device 10 protrudes in the direction d2, the display surface 100a of the display panel 100 is concave, i.e. the flexible display device 10 is mostly folded inward.

It should be noted that, in the present embodiment, the dark bands 213b of the side walls 213 of the supporting plate 210, the bright bands 213a of the side walls 213 of the supporting plate 210, the dark bands 223b of the side walls 223 of the supporting plate 220, and the bright bands 223a of the side walls 223 of the supporting plate 220 are sequentially arranged along the direction d2 (i.e., the protruding direction of the flexible display device 10). The

bright bands

213a, 223a are less likely to crack than the

dark bands

213b, 223b under the same stress. By placing the

bright bands

213a, 223a at locations where the stress is large (e.g., near the surfaces 212, 222), the supporting

plates

210, 220 are less likely to break due to repeated bending.

It should be noted that the following embodiments follow the element numbers (reference numbers) and part of the contents of the foregoing embodiments, wherein the same reference numbers are used to indicate the same or similar elements, and the description of the same technical contents is omitted. For the description of the omitted portions, reference may be made to the foregoing embodiments, which will not be repeated below.

Referring to fig. 5, fig. 6 and fig. 7, similarly, the flexible display device 10A includes a display panel 100 and a reinforcing structure 200A disposed under the display panel 100. The reinforcing structure 200A includes a plurality of supporting

plates

210 and 220 and an adhesive layer 230 disposed between the plurality of supporting

plates

210 and 220. The supporting plate 220, the adhesive layer 230, the supporting plate 210 and the display panel 100 are sequentially stacked in the direction d 1.

Unlike the flexible display device 10A, in the present embodiment, the flexible display device 10A is often convex in a direction d2 that is consistent with the direction d 1. When the flexible display device 10A protrudes in the direction d2, the display surface 100A of the display panel 100 protrudes outward, i.e., the flexible display device 10A is mostly folded outward.

In the present embodiment, the thickness H of the support plate 210₁Is less than the thickness H of the supporting plate 220₂. Further, in the present embodiment, the thickness ratio (H) of the supporting

plates

210, 220₁/H₂) So as to satisfy: 0.33 (H)₁/H₂) Preferably, the content is 1 or less, but the present invention is not limited thereto.

In addition, in the flexible display device 10 of fig. 1, 2 and 3, the dark band 213b of the supporting plate 210 is closer to the display panel 100 than the bright band 213a thereof, and the dark band 223b of the sidewall 223 of the supporting plate 220 is closer to the display panel 100 than the bright band 223a thereof; however, in the present embodiment, the bright band 213a of the supporting plate 210 is closer to the display panel 100 than the dark band 213b thereof, and the bright band 223a of the supporting plate 220 is closer to the display panel 100 than the dark band 223b thereof.

The flexible display device 10A of the present embodiment also has the advantage of bending resistance of the flexible display device 10, which is the same as or similar to the foregoing embodiments, and thus will not be repeated here.

Claims

1. A flexible display device includes:

a display panel; and

a reinforcing structure disposed under the display panel and comprising:

a first support plate;

a second support plate; and

the adhesive layer is arranged between the first supporting plate and the second supporting plate;

the flexible display device is used for protruding towards a direction, and the first dark band and the first bright band are sequentially arranged along the direction.

2. The flexible display device according to claim 1, wherein the roughness of the first dark band is greater than the roughness of the first bright band.

3. The flexible display device according to claim 1, wherein a sidewall of the second supporting plate has a second bright band and a second dark band, and the second dark band and the second bright band are sequentially arranged along the direction.

4. The flexible display device of claim 1, wherein the first support plate and the second support plate are sequentially arranged along the direction, and a thickness of the second support plate is smaller than a thickness of the first support plate.

5. The flexible display device of claim 4, wherein the thickness of the first support plate is H₁The thickness of the second supporting plate is H₂And 1 is less than or equal to (H)₁/H₂)≤3。

6. The flexible display device of claim 1, wherein the first support plate has a Young's modulus E₁The first support plate has a thickness H₁The side wall of the first supporting plate has a length L₁The second supporting plate has a Young's modulus E₂The second support plate has a thickness H₂A side wall of the second supporting plate has a length L₂And is and

7. the flexible display device of claim 1, wherein the first support plate has an area larger than an area of the second support plate.

8. A flexible display device includes:

a display panel; and

a reinforcing structure disposed under the display panel and comprising:

a first support plate having a Young's modulus E₁Wherein 100 GPa. ltoreq. E₁≤250GPa；

A second supporting plate having a Young's modulus E₂Wherein 100 GPa. ltoreq. E₂Less than or equal to 250 GPa; and

an adhesive layer disposed between the first support plate and the second support plate,

9. The flexible display device according to claim 8, wherein the roughness of the first dark band is greater than the roughness of the first bright band.

10. The flexible display device according to claim 8, wherein a sidewall of the second supporting plate has a second bright band and a second dark band, and the second dark band and the second bright band are sequentially arranged along the direction.

11. The flexible display device according to claim 8, wherein the flexible display device is configured to protrude in a direction, the first supporting plate and the second supporting plate are sequentially arranged along the direction, and a thickness of the second supporting plate is smaller than a thickness of the first supporting plate.

12. The flexible display device of claim 11, wherein the thickness of the first support plate is H₁The thickness of the second supporting plate is H₂And H is₁And H₂Satisfies the following formula: 1 is less than or equal to (H)₁/H₂)≤3。

13. The flexible display device of claim 8, wherein the first support plate has a thickness H₁A side wall of the first support plate has a length L₁The second support plate has a thickness H₂A side wall of the second supporting plate has a length L₂And is and

14. the flexible display device of claim 8, wherein the first support plate has an area larger than an area of the second support plate.