TWI737211B - Flexible display apparatus - Google Patents

Abstract

A flexible display apparatus includes a display panel and a reinforcing structure. The reinforcement structure is arranged under the display panel. The reinforcing structure includes a first support plate, a second support plate and an adhesive layer disposed between the first support plate and the second support plate. The first support plate has a Young's modulus E₁ .

. The second support plate has a Young's modulus E₂ .

Description

Flexible display device

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

Recently, with the rise of foldable electronic devices (for example, foldable mobile phones), the development of flexible display panels has once again been emphasized. Generally speaking, in order to support the flexible substrate in the flexible display panel and provide sufficient stiffness, a plate with excellent stiffness and ductility is arranged under the flexible display panel. However, after the flexible display panel is repeatedly bent, the plate of the flexible display panel will crack at the central axis of the bending, which may cause the flexible display panel to fail.

The invention provides a flexible display device with good performance.

A flexible display device according to an embodiment of the invention includes a display panel and a reinforcing structure. The reinforcing structure is arranged under the display panel. The reinforcing structure includes a first supporting plate, a second supporting plate, and an adhesive layer arranged between the first supporting plate and the second supporting plate. The side wall of the first support plate has a first bright band and a first dark band, the flexible display device is used for protruding in a direction, and the first dark band and the first bright band are arranged in sequence along the direction.

。第二支撐板具有楊氏模數E₂ 。

。A flexible display device according to an embodiment of the invention includes a display panel and a reinforcing structure. The reinforcing structure is arranged under the display panel. The reinforcing structure includes a first supporting plate, a second supporting plate, and an adhesive layer arranged between the first supporting plate and the second supporting plate. The first support plate has a Young's modulus E ₁ .

. The second support plate has a Young's modulus E ₂ .

.

Reference will now be made in detail to the exemplary embodiments of the present invention, and examples of the exemplary embodiments are illustrated in the accompanying drawings. Whenever possible, the same component symbols are used in the drawings and descriptions to indicate the same or similar parts.

It should 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 Intermediate elements can 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. As used herein, "connected" can refer to physical and/or electrical connection. Furthermore, "electrically connected" or "coupled" may mean that there are other elements between two elements.

As used herein, "about", "approximately", or "substantially" includes the stated value and the average value within the acceptable deviation range of the specific value determined by a person of ordinary skill in the art, taking into account the measurement in question and the The specific amount of measurement-related error (ie, the limitation of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, "about", "approximately" or "substantially" as used herein can be based on optical properties, etching properties or other properties to select a more acceptable range of deviation or standard deviation, and not one standard deviation can be applied to all properties .

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of related technologies and the present invention, and will not be interpreted as idealized or excessive The formal meaning, unless explicitly defined as such in this article.

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

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

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

Please refer to FIGS. 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 this embodiment, the flexible display device 10 may further include an optical glue 300. The optical glue 300 is disposed between the display panel 100 and the reinforcing structure 200, and the display panel 100 and the reinforcing structure 200 can be connected to each other by the optical glue 300. However, the present invention is not limited to this.

In this embodiment, the flexible display device 10 may further include a light-transmitting cover 400 disposed on the display surface 100 a of the display panel 100. In this embodiment, the flexible display device 10 further includes an optical glue 500. The optical glue 500 is disposed between the light-transmitting cover 400 and the display panel 100, and the light-transmitting cover 400 and the display panel 100 can use the optical glue 500. Are connected to each other, but the present invention is not limited to this.

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

The reinforcement 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 supporting plates 210 and 220 are connected to each other by an adhesive layer 230. For example, in this embodiment, the adhesive layer 230 is, for example, optically clear adhesive (OCA), but the invention is not limited thereto.

In this embodiment, based on the consideration of fitting tolerance, the area of one of the plurality of support plates 210 and 220 may be selectively larger than the area of the other. For example, in this embodiment, the area of the support plate 210 close to the display panel 100 may be larger than the area of the support plate 220 far from the display panel 100, but the invention is not limited to this. However, in another embodiment not shown, it is also possible that the area of the supporting plate 220 far from the display panel 100 is larger than the area of the supporting plate 210 close to the display panel 100.

，且

。The reinforcing structure 200 is used to support the soft display panel 100 so that the flexible display device 10 as a whole has sufficient stiffness and bending resistance. In order to take into account the overall stiffness and bendability of the flexible display device 10, the Young's modulus E _{1 of the supporting plate 210 of the reinforcing structure 200 and the Young's modulus E 2} of the supporting plate 220 of the reinforcing structure 200 should fall on Appropriate range. For example, in this embodiment,

,and

.

---（式1） 。在式（1）中，E₁ 是指支撐板210的楊氏模數，L₁ 是指支撐板210的側壁213的長度，H₁ 是指支撐板210的厚度（即側壁213的高度），E₂ 是指支撐板220的楊氏模數，L₂ 是指支撐板220的側壁223的長度，而H₂ 是指支撐板220的厚度（即側壁223的高度）。The material of the support plates 210 and 220 is preferably selected to have both high ductility and high stiffness. For example, in this embodiment, the material of the support plates 210 and 220 is, for example, stainless steel. However, the present invention is not limited to this. In other embodiments, the supporting plates 210 and 220 may also be made of other metal materials. For example, the following formula (1) can be used to evaluate whether other metal materials are suitable.

---(Formula 1) . In formula (1), E ₁ refers to the Young's modulus of the supporting plate 210, L ₁ refers to the length of the side wall 213 of the supporting plate 210, and H ₁ refers to the thickness of the supporting plate 210 (that is, the height of the side wall 213), E ₂ refers to the Young's modulus of the supporting plate 220, L ₂ refers to the length of the side wall 223 of the supporting plate 220, and H ₂ refers to the thickness of the supporting plate 220 (that is, the height of the side wall 223).

It is worth mentioning that, since the reinforcing structure 200 is composed of a plurality of supporting plates 210, 220 and an adhesive layer 230 sandwiched therebetween, the thickness H ₁ , H ₂ of each supporting plate 210, 220 of the reinforcing structure 200 can be Thinner. In this way, the distance between the surfaces 212, 222 of the support plates 210, 220 and the neutral surfaces S1, S2 of the support plates 210, 220 will be shorter, and the stress on the surfaces 212, 222 of the support plates 210, 220 will be less. , So that the reinforcing structure 200 is not easy to crack due to repeated bending. _{In addition, since the thickness H 1} , H ₂ of each support plate 210, 220 of the reinforcing structure 200 is thin, the support plate 210, 220 is not easy to produce creases, which helps to reduce the bending radius of the flexible display device 10.

Referring to FIGS. 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 the direction d1. In this embodiment, the flexible display device 10 is configured to protrude in a direction d2 opposite to the direction d1. When the flexible display device 10 is convex in the direction d2, the display surface 100a of the display panel 100 is concave inward. In other words, the flexible display device 10 of this embodiment is mainly used for folding inward.

In this embodiment, the supporting plate 210 and the supporting plate 220 are arranged in order along the direction d2 (that is, the convex direction of the flexible display device 10), and the thickness H _{2 of the} supporting plate 220 is smaller than the thickness H _{1 of the} supporting plate 210. _{In other words, the thickness H 2} of the supporting plate 220 subjected to greater stress is thinner _{than the thickness H 1} of the supporting plate 210 subjected to less stress. Thereby, the distance between the surface 222 of the support plate 220 and the neutral surface S2 is shorter, the stress on the surface 222 of the support plate 220 is further reduced, and the crack of the support plate 220 due to repeated bending is further reduced. Probability.

The following Table 1 shows the various thicknesses H ₁ and H ₂ of the supporting plates 210 and 220 of the reinforcing structure 200 and the maximum principal stress experienced by the reinforcing structure 200 according to an embodiment of the present invention. Condition one Condition two Condition three Condition four Condition five Thickness H ₁ (µm) 15 20 22.5 25 30 Thickness H ₂ (µm) 25 20 27.5 15 10 Maximum principal stress (MPa) 766 663 616 580 684 [Table I]

The flexible display device (not shown) of the first comparative example is similar to the flexible display device of this embodiment, and the difference between the two is only: the reinforcing structure of the flexible display device of the first comparative example is a support Without the adhesive layer 230, and the thickness of the supporting plate of the reinforcing structure of the flexible display device of the comparative example is equal to the thickness H of the plurality of supporting plates 210, 220 of the reinforcing structure 200 of the flexible display device 10 of this embodiment ₁ , H ₂ and. The thickness of the support plate of the reinforcing structure of the flexible display device of the first comparative example is 40 μm, and the maximum principal stress of the reinforcing structure of the flexible display device of the first comparative example is 1045 MPa. The maximum principal stresses of the flexible display device 10 of this embodiment under conditions 1 to 5 are 776 MPa, 663 MPa, 616 MPa, 580 MPa and 684 MPa, respectively. Compared with the maximum principal stress of 1045 MPa in the first comparative example, this embodiment is The maximum principal stress of the flexible display device 10 is significantly lower. In addition, according to Table 1 above, it can be found that in this embodiment, the thickness ratio (H ₁ /H ₂ ) of the support plates 210 and 220 satisfies 1≤(H ₁ /H ₂ )≤3, which is better, but The present invention is not limited to this.

The flexible display device (not shown) of the second comparative example is similar to the flexible display device 10 of this embodiment, and the flexible display device (not shown) of the second comparative example is similar to the flexible display device of this embodiment. The flexible display device 10 has the same total thickness. The only difference between the two is that the reinforcing structure of the flexible display device of the second comparative example is a support plate and has no adhesive layer 230. The flexible display device of the second comparative example _{The thickness of the supporting plate of the reinforcing structure is equal to the thickness H 1} , H ₂ and the thickness of the supporting plate 210 of the reinforcing structure 200 of the flexible display device 10 of this embodiment, and the thickness of the flexible display device of the second comparative example The thickness of the optical adhesive 300 of the reinforcing structure is equal to the sum of the thickness of the optical adhesive 300 of the flexible display device 10 of this embodiment and the thickness of the adhesive layer 230. According to a simulation result, the maximum stress experienced by the flexible display device of the second comparative example is 1182 MPa, and the maximum stress experienced by the flexible display device of this embodiment is 681 MPa. That is to say, compared to the second comparative example, in this embodiment, even if the solid adhesive layer 300 is thinner, the stress received by the reinforcing structure 200 with multiple supporting plates 210 and 200 is still stronger than that of the second comparative example. The stress on the structure is low.

FIG. 4 shows the bright bands 213a, 223a and the dark bands 213b, 223b of the side walls 213, 223 of the supporting plates 210, 220 of an embodiment of the present invention observed with an optical microscope.

1, 3 and 4, the support plate 210 has a surface 211 facing the display panel 100, a surface 212 facing away from the display panel 100, and a side wall 213 connected between the surface 211 and the surface 212; the support plate 220 has a surface facing The surface 221 of the display panel 100, the surface 222 facing away from the display panel 100, and the sidewall 223 connected between the surface 221 and the surface 222. In this embodiment, a tool can be used to punch a mother board to form the side walls 213 and 223 of the plurality of support plates 210 and 220. On the side walls 213, 223 of the support plates 210, 220, it can be observed that near the lower knife, the side walls 213, 223 have bright bands 213a, 223a; when far away from the lower knife, the side walls 213, 223 have dark bands 213b, 223b. The bright bands 213a, 223a are formed when the tool punches the mother board, and the dark bands 213b, 213b are formed when the support plates 210, 220 are disconnected from the mother board. Therefore, the roughness of the bright bands 213a, 223a is darker. The roughness of the belts 213b and 213b is small (in other words, the roughness of the dark belts 213b and 213b is larger than the roughness of the bright belts 213a and 223a), and the bright belts 213a and 223a look brighter than the dark belts 213b and 213b.

Referring to FIGS. 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 the direction d1. In this embodiment, the flexible display device 10 is mostly used to bulge in a direction d2 opposite to the direction d1. When the flexible display device 10 is convex in the direction d2, the display surface 100a of the display panel 100 is concave, that is, the flexible display device 10 is mostly used for folding inward.

It is worth noting that, in this embodiment, the dark band 213b of the side wall 213 of the support plate 210, the bright band 213a of the side wall 213 of the support plate 210, the dark band 223b of the side wall 223 of the support plate 220, and the side wall 223 of the support plate 220 The bright strips 223a are arranged in order along the direction d2 (that is, the convex direction of the flexible display device 10). Under the same stress, the bright bands 213a and 223a are less prone to cracks than the dark bands 213b and 223b. By placing the bright strips 213a and 223a in places subject to greater stress (for example, near the surfaces 212 and 222), the supporting plates 210 and 220 are less likely to be cracked due to repeated bending.

It must be noted here that the following embodiments use the element numbers and part of the content of the foregoing embodiments, wherein the same numbers are used to represent the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, and the following embodiments will not be repeated.

FIG. 5 is a schematic side view of an unfolded flexible display device 10A according to an embodiment of the present invention.

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

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

Please refer to FIGS. 5, 6 and 7, similarly, the flexible display device 10A includes a display panel 100 and a reinforcing structure 200A disposed under the display panel 100. The reinforcement structure 200A includes a plurality of supporting plates 210 and 220 and an adhesive layer 230 arranged 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 d1.

Different from the aforementioned flexible display device 10A, in this embodiment, the flexible display device 10A is mostly used to protrude in a direction d2 that is consistent with the direction d1. When the flexible display device 10A is convex in the direction d2, the display surface 100a of the display panel 100 is convex outward, that is, the flexible display device 10A is mostly folded outward.

In this embodiment, the thickness H _{1 of the} support plate 210 is smaller than the thickness H _{2 of the} support plate 220. Furthermore, in this embodiment, the thickness ratio (H ₁ /H ₂ ) of the support plates 210 and 220 is satisfied, 0.33 ≤ (H ₁ /H ₂ ) ≤ 1, but this is not the case in the present invention. limit.

In addition, in the aforementioned flexible display device 10 of FIGS. 1, 2 and 3, the dark band 213b of the support plate 210 is closer to the display panel 100 than the bright band 213a, and the dark band 223b of the side wall 223 of the support plate 220 The bright band 223a is closer to the display panel 100; but in this embodiment, the bright band 213a of the support plate 210 is closer to the display panel 100 than the dark band 213b, and the bright band 223a of the support plate 220 is closer to the dark band 223b. The display panel 100.

The flexible display device 10A of this embodiment also has the advantage of bending resistance of the aforementioned flexible display device 10, and the reason is the same as or similar to the aforementioned embodiment, and will not be repeated here.

10.10A: Flexible display device 100: Display panel 100a: Display surface 200, 200A: Reinforced structure 210, 220: Support plate 211, 212, 221, 222: Surface 213, 223: Side wall 213a, 223a: Bright strip 213b , 223b: dark band 230: adhesive layer 300: optical adhesive 400: light transmitting cover 500: optical glue d1, d2: the direction of H _1, H _2: thickness L _1, L _2: length S1, S2: neutral plane

FIG. 1 is a schematic side view of an unbent flexible display device 10 according to an embodiment of the present invention. FIG. 2 is a schematic side view of a bent flexible display device 10 according to an embodiment of the present invention. FIG. 3 is a schematic side view of a reinforcing structure 200 according to an embodiment of the present invention. FIG. 4 shows the bright bands 213a, 223a and the dark bands 213b, 223b of the side walls 213, 223 of the supporting plates 210, 220 of an embodiment of the present invention observed with an optical microscope. FIG. 5 is a schematic side view of an unfolded flexible display device 10A according to an embodiment of the present invention. FIG. 6 is a schematic side view of a bent flexible display device 10A according to an embodiment of the present invention. FIG. 7 is a schematic side view of a reinforcing structure 200A according to an embodiment of the present invention.

10: Flexible display device

100: display panel

100a: display surface

200: Strengthen the structure

210, 220: support plate

211, 212, 221, 222: surface

213, 223: side wall

230: Adhesive layer

300: Optical glue

400: Translucent cover

500: Optical glue

d1: direction

H ₁ , H ₂ : thickness

L ₁ , L ₂ : length

S1, S2: neutral side

Claims (14)

A flexible display device, comprising: a display panel; and a reinforcing structure, arranged under the display panel, and comprising: a first supporting plate; a second supporting plate; and an adhesive layer arranged on the first Between the supporting plate and the second supporting plate; wherein, a side wall of the first supporting plate has a first bright band and a first dark band, the flexible display device is used for protruding in one direction, and the first A dark band and the first bright band are sequentially arranged along the direction. According to the flexible display device described in claim 1, wherein the roughness of the first dark band is greater than the roughness of the first bright band. According to the flexible display device described in claim 1, wherein a side wall of the second support plate has a second bright band and a second dark band, and the second dark band and the second bright band Arrange in order along this direction. According to the flexible display device described in claim 1, wherein the first supporting plate and the second supporting plate are arranged in order along the direction, and a thickness of the second supporting plate is smaller than that of the first supporting plate的一厚。 One thickness. The flexible display device according to claim 4, wherein the thickness of the first support plate is H ₁ , the thickness of the second support plate is H ₂ , and 1

(H ₁ /H ₂ )

3. The flexible display device described in claim 1, wherein the first support plate has a Young's modulus E ₁ , the first support plate has a thickness H ₁ , and the side wall of the first support plate Has a length L ₁ , the second support plate has a Young's modulus E ₂ , the second support plate has a thickness H ₂ , a side wall of the second support plate has a length L ₂ and is 200 GPa

E ₁ × L ₁ ×

+E ₂ × L ₂ ×

. According to the flexible display device described in claim 1, wherein the area of the first support plate is larger than the area of the second support plate. A flexible display device includes: a display panel; and a reinforcement structure, arranged under the display panel, and includes: a first support plate having a Young's modulus E ₁ , of which 100 GPa

E ₁

250GPa; a second support plate with a Young's modulus E ₂ , of which 100GPa

E ₂

250GPa; and an adhesive layer disposed between the first support plate and the second support plate, wherein a side wall of the first support plate has a first bright band and a first dark band, the flexible display The device is used to bulge in one direction, and the first dark band and the first bright band are arranged in sequence along the direction. The flexible display device described in item 8 of the scope of patent application, wherein the roughness of the first dark band is greater than the roughness of the first bright band. The flexible display device described in item 8 of the scope of patent application, wherein a side wall of the second support plate has a second bright band and a second dark band, and the second dark band and the second bright band Arrange in order along this direction. The flexible display device according to claim 8, wherein the first supporting plate and the second supporting plate are arranged in order along the direction, and a thickness of the second supporting plate is smaller than that of the first supporting plate的一厚。 One thickness. The flexible display device according to claim 11, wherein the thickness of the first support plate is H ₁ , the thickness of the second support plate is H ₂ , and H ₁ and H ₂ satisfy the following formula :1

(H ₁ /H ₂ )

3. The flexible display device according to claim 8, wherein the first support plate has a thickness H ₁ , a side wall of the first support plate has a length L ₁ , and the second support plate has a Thickness H ₂ , a side wall of the second support plate has a length L ₂ , and 200 GPa

E ₁ × L ₁ ×

+E ₂ × L ₂ ×

. The flexible display device described in item 8 of the scope of patent application, wherein the area of the first support plate is larger than the area of the second support plate.

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