CN112382198A

CN112382198A - Flexible display screen, preparation method thereof and flexible display device

Info

Publication number: CN112382198A
Application number: CN202011244495.4A
Authority: CN
Inventors: 董文伯
Original assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co Ltd
Current assignee: Wuhan China Star Optoelectronics Semiconductor Display Technology Co Ltd
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-02-19
Anticipated expiration: 2040-11-10
Also published as: CN112382198B

Abstract

The invention provides a flexible display screen, a preparation method thereof and a flexible display device. The flexible display screen comprises a display panel, a cover plate attached to the upper surface of the display panel and a back plate attached to the lower surface of the display panel. The backboard is provided with a plurality of hollow parts, each hollow part comprises two sections of first arcs with opposite openings and two transition lines connecting the two sections of first arcs, and the row spacing between every two adjacent hollow parts and the first curvature radius of the two sections of first arcs meet a preset relation. So as to relieve the risk of peeling off the film layer of the prior rollable display product.

Description

Flexible display screen, preparation method thereof and flexible display device

Technical Field

The invention relates to the technical field of display, in particular to a flexible display screen, a preparation method thereof and a flexible display device.

Background

The OLED display technology has the advantages of being soft and deformable due to the fact that the flexible film is used as the substrate, and can meet various flexible application scenes. Such as foldable (foldable) display products and Rollable (Rollable) display products that appear to increase the image display area to enhance the user's visual perception.

Rollable display products have a higher requirement for flexibility than foldable display products. In the working process of the foldable display product, the bending area is fixed, and the maximum stress area of the panel (panel) is fixed. And the deformation range of the panel is smaller, and the dislocation caused by the limited deformation of the bending is also smaller. The maximum stress area of the panel is continuously changed in the process of winding and unwinding the rollable display product each time, and the rollable display product is gradually pushed forward along with the winding (unwinding). And then because the deformation that the roll-up brought constantly outside accumulates, make the panel produce the risk of retelling and peeling off (peeling) extremely high.

Therefore, the problem of the film peeling risk of the existing rollable display product needs to be solved.

Disclosure of Invention

The invention provides a flexible display screen, a preparation method thereof and a flexible display device, which are used for relieving the technical problem that the conventional rollable display product has a film peeling risk.

In order to solve the above problems, the technical scheme provided by the invention is as follows:

the embodiment of the invention provides a flexible display screen, which comprises a display panel, a cover plate and a back plate. The cover plate is arranged on the light emergent surface of the display panel. The back plate is arranged on the surface of the display panel departing from the cover plate. The backboard is provided with a plurality of hollow parts, the shape of each hollow part comprises two sections of first arcs with opposite openings and two transition lines connecting the two sections of first arcs, and the row spacing between every two adjacent hollow parts and the first curvature radius of the two sections of first arcs meet a preset relationship.

In the flexible display screen provided by the embodiment of the invention, the two transition lines are two second arcs with opposite openings, the column distance between two adjacent hollow-out portions is a first column distance (D1), and the preset relationship that the first column distance (D1) and the first curvature radius (R1) satisfy is as follows: 2/3 (D1-2R1)/R1 (2/1) is not more than; and the first radius of curvature (R1) and a second radius of curvature (R2) of the second circular arc satisfy the following relationship: 1/60 is less than or equal to R1/R2 is less than or equal to 1/80.

In the flexible display screen provided by the embodiment of the invention, the two transition lines are two third arcs with opposite openings, the column distance between two adjacent hollow-out portions is a second column distance (D2), and the preset relationship that the second column distance (D2) and the first curvature radius (R1) satisfy is as follows: 2/3 (D2-2R1)/R1 (2/1) is not more than; and the first radius of curvature (R1) and a third radius of curvature (R3) of the third arc satisfy the following relationship: 1/80 is less than or equal to R1/R3 is less than or equal to 1/90.

In the flexible display screen provided by the embodiment of the invention, the two transition lines are two straight lines, the column distance between two adjacent hollow-out portions is a third column distance (D3), and the preset relationship that the third column distance (D3) and the first radius of curvature (R1) satisfy is as follows: 2/3 is not less than D3/R1 is not less than 2/1.

In the flexible display screen provided by the embodiment of the invention, the hollow parts are arranged on the whole surface of the back plate and are arranged in a staggered manner.

In the flexible display screen provided by the embodiment of the invention, the hollow parts are arranged in partial areas of the back plate and are arranged in a staggered manner.

In the flexible display screen provided by the embodiment of the invention, the back plate is divided into a plurality of partitions, each partition is provided with the hollow part, and the lengths of the hollow parts of the plurality of partitions are gradually increased in a gradient manner.

The embodiment of the invention also provides a preparation method of the flexible display screen, which comprises the following steps: step S10, providing a back plate, wherein a plurality of hollowed-out parts are arranged on the back plate, each hollowed-out part comprises two first circular arcs with opposite openings and two transition lines connecting the two first circular arcs, and the column spacing between every two adjacent hollowed-out parts and the first curvature radius of the two first circular arcs meet a preset relationship; step S20, providing a display panel, including attaching the display panel on the backboard; and step S30, attaching a cover plate, including attaching the cover plate on the surface of the display panel far away from the back plate.

In the preparation method of the flexible display screen provided by the embodiment of the invention, the two transition lines comprise two straight lines or two second arcs with opposite openings or two third arcs with opposite openings.

The embodiment of the invention also provides a flexible display device which comprises the flexible display screen in one of the previous embodiments.

The invention has the beneficial effects that: in the flexible display screen, the preparation method thereof and the flexible display device provided by the invention, the plurality of hollow parts are arranged on the back plate so as to reduce the stress generated by the flexible display screen in different working modes, further reduce the risk of film peeling of the flexible display screen and prolong the service life of the flexible display screen under the condition of high stress.

Drawings

In order to illustrate the embodiments or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the invention, and it is obvious for a person skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic cross-sectional structural diagram of a flexible display screen according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a first top view structure of a back plate according to an embodiment of the present invention;

FIG. 3 is an enlarged view of a portion of FIG. 2;

fig. 4 is a first structural schematic diagram of a hollow portion according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a second top view of a back plate according to an embodiment of the present invention;

fig. 6 is a schematic view of a second structure of the hollow portion according to the embodiment of the present invention;

FIG. 7 is a schematic diagram of a third top view of a back plate according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a fourth top view of a back plate according to an embodiment of the present invention;

FIG. 9 is a schematic top view of the backplane structure of FIG. 8 with different partitions;

FIG. 10 is a schematic diagram of a fifth top view of a back plate according to an embodiment of the present invention;

FIG. 11 is an enlarged schematic view of the structure of each hollow portion of the backplate structure shown in FIG. 10;

fig. 12 is a schematic flow chart of a method for manufacturing a flexible display screen according to an embodiment of the present invention.

Detailed Description

The following description of the various embodiments refers to the accompanying drawings that illustrate specific embodiments in which the invention may be practiced. The directional terms mentioned in the present invention, such as [ upper ], [ lower ], [ front ], [ rear ], [ left ], [ right ], [ inner ], [ outer ], [ side ], are only referring to the directions of the attached drawings. Accordingly, the directional terms used are used for explanation and understanding of the present invention, and are not used for limiting the present invention. In the drawings, elements having similar structures are denoted by the same reference numerals. In the drawings, the thickness of some layers and regions are exaggerated for clarity of understanding and ease of description. That is, the size and thickness of each component shown in the drawings are arbitrarily illustrated, but the present invention is not limited thereto.

In an embodiment, please refer to fig. 1 to 4 in combination, fig. 1 is a schematic cross-sectional view of a flexible display panel provided in the present invention, and the flexible display panel 100 of the present invention can be bent or rolled. The flexible display screen 100 includes a display panel 20, a cover plate 30, and a back plate 10. The cover plate 30 is disposed on the light emitting surface of the display panel 20. The light emitting surface of the display panel 20 refers to a surface of the display panel 20 that presents display pixels, i.e., an upper surface of the display panel 20. The back plate 10 is disposed on a surface of the display panel 20 facing away from the cover plate 30, i.e., a lower surface of the display panel 20. The back plate 10 is provided with a plurality of hollow portions 11, each hollow portion 11 includes two first circular arcs C1 with opposite openings and two transition lines T-line connecting the two first circular arcs C1, and a column distance between every two adjacent hollow portions 11 and a first curvature radius R1 of the two first circular arcs C1 satisfy a preset relationship.

Specifically, the display panel 20 may include a flexible substrate 21, a driving circuit layer 22 disposed on the flexible substrate 21, a light emitting function layer 23 disposed on the driving circuit layer 22, and an encapsulation layer 24 disposed on the light emitting function layer 23. The back plate 10 is disposed on a lower surface of the display panel 20, that is, on a surface of the flexible substrate 21 away from the driving circuit layer 22, and is configured to support the flexible substrate 21 and each film layer on the flexible substrate 21, and to structurally reinforce the flexible substrate 21.

Further, referring to fig. 2 to 4, fig. 2 is a schematic view of the entire arrangement of the hollow portions 11 on the back plate 10, fig. 3 is a schematic view of a portion W in fig. 2, and fig. 4 is a schematic view of the structure of a single hollow portion 11 in fig. 3. The back plate 10 is provided with a plurality of hollow parts 11, and the hollow parts 11 are arranged on the whole surface of the back plate 10 in a staggered manner. Each of the hollow portions 11 includes two first circular arcs C1 with opposite openings and two transition lines T-line connecting the two first circular arcs C1. The arc length and the curvature radius of the two first circular arcs C1 are equal, that is, the curvature radius of the two first circular arcs C1 is the first curvature radius R1. The two transition lines T-line are two second arcs C2 with opposite openings, so that the hollow part 11 is in a convex strip shape. The arc length and the curvature radius of the two second circular arcs C2 are also equal, that is, the curvature radius of the two second circular arcs C2 is the second curvature radius R2. As shown in fig. 4, the distance from the first center O1 to the first circular arc C1 is the first radius of curvature R1, and the distance from the second center O2 to the second circular arc C2 is the second radius of curvature R2. The first radius of curvature R1 and the second radius of curvature R2 satisfy the following relationship: 1/60 is less than or equal to R1/R2 is less than or equal to 1/80. Of course, the present invention is not limited thereto, and the arc length and the curvature radius of the two first circular arcs C1 or the two second circular arcs C2 may not be equal.

Specifically, the arrangement of the hollow parts 11 in a staggered manner means that the hollow parts 11 are regularly arranged in a staggered manner. Referring to fig. 2 and 3, the hollow portions 11 are arranged in rows in order, each row is parallel to the other row, and the hollow portions 11 between two adjacent rows are staggered. The centers of the first circular arcs C1 on each row of the hollow-out parts 11 are on a straight line. The intervals between the adjacent hollow parts 11 on each row of the hollow parts 11 are the same, that is, the row intervals of two adjacent hollow parts 11 are the same. The interval between two adjacent columns is also the same, that is, the column interval between two adjacent hollow parts 11 is the same. As shown in fig. 3, a row interval between two adjacent hollow-out portions 11 is a first row interval S1, and a column interval between two adjacent hollow-out portions 11 is a first column interval D1. The first column spacing D1 and the first radius of curvature R1 satisfy the following relationship: 2/3 (D1-2R1)/R1 (2/1) is less than or equal to. It should be noted that the hollow portions 11 are arranged in a row in order, and the extending direction of the row is parallel to the bending axis X direction of the flexible display screen, as shown in fig. 2. The bending axis X of the flexible display screen refers to a virtual straight line perpendicular to the bending or curling direction Y of the flexible display screen.

Further, when the flexible display screen 100 is folded or rolled in, the back plate 10 is located at the outermost layer of the flexible display screen 100 and is subjected to a tensile stress caused by the module structure of the flexible display screen 100. Set up the fretwork portion 11 that is protruding rectangular shape on backplate 10 to arrange with the whole face of form of alternating expression, the tensile stress that backplate 10 received when can reducing flexible display screen 100 infolding or internal rolling, it is relative, reduce the apron 30 the compressive stress that display panel 20 received, and then reduced flexible display screen 100's display panel 20 the risk that the rete peeled off appears, increased flexible display screen 100 life under the high stress condition.

It is understood that when the flexible display 100 is folded or rolled out, the back plate is located at the innermost layer of the flexible display 100, and the back plate is compressed, which may generate compressive stress. At this moment, the hollow-out part which is in a concave strip shape can be arranged on the back plate, and the back plate is arranged in a staggered mode on the whole surface, so that the compressive stress generated by extrusion of the back plate is reduced, the stress is relatively reduced, the tensile stress borne by the cover plate 30 and the display panel 20 is reduced, the risk that the film layer is peeled off from the display panel 20 of the flexible display screen 100 is reduced, and the service life of the flexible display screen 100 under the high-stress condition is prolonged.

Specifically, referring to fig. 5 and fig. 6, a plurality of hollow portions 11 'are disposed on the back plate 10', and the hollow portions 11 'are arranged on the entire surface of the back plate 10' in a staggered manner. Each of the hollow portions 11' includes two first circular arcs C1 with opposite openings and two transition lines T-line connecting the two first circular arcs C1. The two transition lines T-line are two third arcs C3 with opposite openings, so that the hollow portion 11' is in a concave strip shape. The arc length and the curvature radius of the two third circular arcs C3 are equal, that is, the curvature radius of the two third circular arcs C3 is the third curvature radius R3. As shown in fig. 6, the distance from the third center O3 to the third arc C3 is the third radius of curvature R3. The first radius of curvature R1 and the third radius of curvature R3 satisfy the following relationship: 1/60 is less than or equal to R1/R3 is less than or equal to 1/80. Of course, the present invention is not limited thereto, and the arc length and the curvature radius of the two first circular arcs C1 or the two third circular arcs C3 may not be equal.

Further, as shown in fig. 5, a row interval between two adjacent hollow portions 11 'is a second row interval S2, and a column interval between two adjacent hollow portions 11' is a second column interval D2. The second column spacing D2 and the first radius of curvature R1 satisfy the following relationship: 2/3 (D2-2R1)/R1 (2/1) is less than or equal to.

Of course, the two transition lines of the hollow-out portion of the present invention may also be set as straight lines, so that the hollow-out portion is a strip-shaped neutral hole, and there is no obvious guiding trend of tensile stress and compressive stress, and the stress of the back plate when the flexible display screen 100 is folded inward or rolled inward or folded outward can be reduced. Specifically, referring to fig. 7, a plurality of hollowed-out portions 11 are disposed on the back plate 10 ", and the hollowed-out portions 11 are arranged on the entire surface of the back plate 10 in a staggered manner. Each of the hollow-out portions 11 ″ includes two first circular arcs C1 with opposite openings and two transition lines T-line connecting the two first circular arcs C1. The arc length and the curvature radius of the two first circular arcs C1 are equal, that is, the curvature radius of the two first circular arcs C1 is the first curvature radius R1. The two transition lines T-line are straight lines. The row interval between two adjacent hollow-out parts 11 "is the third row interval S3, and the column interval between two adjacent hollow-out parts 11" is the third column interval D3. The third column spacing D3 and the first radius of curvature R1 satisfy the following relationship: 2/3 is not less than D3/R1 is not less than 2/1.

In an embodiment, different from the above embodiments, the hollowed-out portions are disposed in a partial area of the back plate, and the hollowed-out portions are arranged in a staggered manner. That is, the hollowed-out portion is disposed in the area of the back plate corresponding to the flexible display screen 100 that needs to be bent or curled, and the hollowed-out portion is not disposed in other areas that do not need to be bent or curled.

Specifically, as shown in fig. 8, the back plate 10 "' is divided into a perforated area DH and a non-perforated area, the perforated area DH is provided with hollow portions 11 ' in a concave strip shape, and the hollow portions 11 ' are arranged in an interlaced manner. The length of the perforated region DH is also the length of the flexible display screen curling region RA. The non-punching region is divided into a first region FH1 and a second region FH2, and the first region FH1 and the second region FH2 are located on two opposite sides of the punching region DH. The first region FH1 may be a blank region at the starting end of the flexible display screen 100, and the second region FH2 may be a blank region at the ending end of the flexible display screen 100, where the blank region is not the region where the hollow portion 11' is not located.

Further, the length L1 of the first region FH1 and the length L2 of the second region FH2 satisfy the following relationship: l1 is more than or equal to 0, and L2 is more than or equal to 0. When L1 is 0, the flexible display screen 100 has no blank area at the start of the curling. When L2 is 0, the flexible display screen 100 has no blank area at the end of the curl. When L1 is equal to L2 is equal to 0, a hollow portion is provided on the entire surface of the back plate in the above embodiment.

It can be understood that, referring to fig. 9, during the process of curling the flexible display screen 100 from the curling start end to the curling end, the generated stress gradually accumulates toward the end of the curled region RA as the curling progresses. To reduce stress buildup at the end of crimp zone RA, the length L3 of perforated region DH 'on backsheet 10 "' may be made greater than the length L4 of crimp zone RA. The stress accumulated at the end of the curling region RA is absorbed, and meanwhile, the support of the non-perforated region of the back plate 10 'on the flexible membrane material is not sacrificed, so that the influence of the hollow part 11' on the surface flatness of the display panel is reduced.

Of course, the punching area of the present embodiment may also be provided with a hollow portion in a convex strip shape or a strip-shaped neutral hole to correspond to the flexible display screen 100 with different curling modes. For other descriptions, please refer to the above embodiments, which are not repeated herein.

In an embodiment, different from the above embodiments, the back plate is divided into a plurality of partitions, each partition is provided with the hollow portion, and the lengths of the hollow portions of the plurality of partitions are gradually increased in a gradient manner. Specifically, please refer to fig. 10 and 11, which illustrate an example of disposing five partitions on the backplane 10 "", but the invention is not limited thereto. The sizes of the hollow parts in any two of the five subareas are different, but the sizes of the hollow parts in the same subarea are the same, and the arrangement mode also adopts staggered arrangement. In the five sections, the first section FA1 corresponds to the initial end of the flexible display screen 100, the fifth section FA5 corresponds to the terminal end of the flexible display screen 100, and the size of the hollow part in each section is gradually increased from the first section FA1 to the fifth section FA 5. It should be noted that, in the present invention, the size of the hollow portion is measured mainly by the length of the hollow portion, and the length of the hollow portion refers to the distance between the centers of the two first arcs of the hollow portion. The first curvature radius of the two first arcs of the hollow-out portion may also gradually increase, but the invention is not limited thereto.

Specifically, the length of the hollow part 11-1 in the first partition FA1 is a first length H1, the length of the hollow part 11-2 in the second partition FA2 is a second length H2, the length of the hollow part 11-3 in the third partition FA3 is a third length H3, the length of the hollow part 11-4 in the fourth partition FA4 is a fourth length H4, and the length of the hollow part 11-5 in the fifth partition FA5 is a fifth length H5, wherein H1< H2< H3< H4< H5.

Further, the first sub-area FA1 corresponds to the initial end of the curling, the stress generated by the flexible display screen 100 at the initial end of the curling is small, and the back plate 10 "" corresponding to the initial end of the curling does not need to have too large deformation capacity, and at this time, the first sub-area FA1 can be provided with the hollow part 11-1 with a small size. However, as the curling process continues, the stress gradually accumulates toward the tail end along the curling direction Y, and the back panel 10 ″ corresponding to the curled tail end needs to have a larger deformation capability, and at this time, the fifth sub-area FA5 may be provided with a hollow portion 11-5 having a larger size. When 1< H5/H1. ltoreq.3, a good effect can be obtained. Of course, the relationship satisfied by H5 and H1 in the present invention is not limited thereto.

Further, set up the variation in size in different subregion fretwork portion, just the size of fretwork portion is along with the propulsion crescent of curling, and the continuously variable fretwork portion makes the backplate can deformability different in different subregion, can balance the support nature and the deformability of flexible display screen 100 module structure.

It should be noted that, in the embodiment, the hollow portions in the shape of a concave strip are set in the five sub-areas as an example, and in response to different curling modes, the hollow portions in the shape of a convex strip or a strip neutral hole may also be set in the five sub-areas. For other descriptions, please refer to the above embodiments, which are not repeated herein.

In an embodiment, there is provided a method for manufacturing a flexible display screen, as shown in fig. 12, including the following steps:

please refer to fig. 1 to fig. 4. Step S10, providing a back plate 10, wherein the back plate 10 is provided with a plurality of hollow portions 11, each hollow portion 11 includes two first arcs C1 with opposite openings and two transition lines T-line connecting the two first arcs C1, and a column distance between each two adjacent hollow portions 11 and a first curvature radius R1 of the two first arcs C1 satisfy a preset relationship;

step S20, providing a display panel 20, including attaching the display panel 20 to the back plate 10;

step S30, attaching the cover 30, including attaching the cover 30 on the surface of the display panel 20 away from the back plate 10, to form the flexible display screen 100 shown in fig. 1.

Specifically, referring to fig. 2 to 4, in step S10, the hollowed portions 11 are disposed on the entire surface of the back plate 10, and the hollowed portions 11 are arranged in a staggered manner. The arc length and the curvature radius of the two first circular arcs C1 of each hollow part 11 are equal, that is, the curvature radius of the two first circular arcs C1 is the first curvature radius R1. The two transition lines T-line are two second arcs C2 with opposite openings, so that the hollow part 11 is in a convex strip shape. The arc length and the curvature radius of the two second circular arcs C2 are also equal, that is, the curvature radius of the two second circular arcs C2 is the second curvature radius R2. The column distance between two adjacent hollow portions 11 is a first column distance D1, and the preset relationship that the first column distance D1 and the first radius of curvature R1 satisfy is: 2/3 (D1-2R1)/R1 (2/1) is less than or equal to. And the first curvature radius R1 and the second curvature radius R2 of the second circular arc C2 satisfy the following relationship: 1/60 is less than or equal to R1/R2 is less than or equal to 1/80.

Specifically, in step S30, the cover plate 30 is attached to the upper surface of the display panel 20 by a transparent optical Adhesive (OCA).

It should be noted that, the method for manufacturing the flexible display screen in this embodiment takes the case that the hollow portions which are arranged in a staggered manner and are in a convex strip shape are arranged on the whole surface of the back plate. However, the manufacturing method of the flexible display screen is not limited to this, and in order to cope with different curling modes, in the manufacturing method of the present invention, the back plate may also be provided with hollow portions having concave strip-shaped or strip-shaped neutral holes, and the hollow portions may also be arranged in a staggered manner in a partial area of the back plate, or arranged on the back plate in a gradient partitioning manner. The specific arrangement and arrangement of the hollow portions can refer to the back plate structure of the flexible display screen in the above embodiments, and details are not repeated here.

In an embodiment, a flexible display device is provided, which comprises the flexible display screen of one of the above embodiments.

According to the above embodiments:

the invention provides a flexible display screen, a preparation method thereof and a flexible display device. The flexible display screen is characterized in that the back plate is provided with a plurality of hollow parts to reduce stress generated by the flexible display screen in different working modes, so that the risk of peeling off a film layer of the flexible display screen is reduced, and the service life of the flexible display screen under a high-stress condition is prolonged.

In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.

Claims

1. A flexible display screen, comprising:

a display panel;

the cover plate is arranged on the light emitting surface of the display panel; and

the back plate is arranged on the surface of the display panel, which is far away from the cover plate;

the backboard is provided with a plurality of hollow parts, the shape of each hollow part comprises two sections of first arcs with opposite openings and two transition lines connecting the two sections of first arcs, and the row spacing between every two adjacent hollow parts and the first curvature radius of the two sections of first arcs meet a preset relationship.

2. The flexible display screen of claim 1, wherein the two transition lines are two second arcs with opposite openings, the column distance between two adjacent hollow-outs is a first column distance (D1), and the preset relationship that the first column distance (D1) and the first radius of curvature (R1) satisfy is: 2/3 (D1-2R1)/R1 (2/1) is not more than; and the first radius of curvature (R1) and a second radius of curvature (R2) of the second circular arc satisfy the following relationship: 1/60 is less than or equal to R1/R2 is less than or equal to 1/80.

3. The flexible display screen of claim 1, wherein the two transition lines are two third arcs with opposite openings, the column distance between two adjacent hollow-out portions is a second column distance (D2), and the preset relationship that the second column distance (D2) and the first curvature radius (R1) satisfy is: 2/3 (D2-2R1)/R1 (2/1) is not more than; and the first radius of curvature (R1) and a third radius of curvature (R3) of the third arc satisfy the following relationship: 1/80 is less than or equal to R1/R3 is less than or equal to 1/90.

4. The flexible display screen of claim 1, wherein the two transition lines are two straight lines, the column distance between two adjacent hollow-outs is a third column distance (D3), and the preset relationship that the third column distance (D3) and the first radius of curvature (R1) satisfy is: 2/3 is not less than D3/R1 is not less than 2/1.

5. The flexible display screen according to any one of claims 1 to 4, wherein the hollowed-out portions are arranged on the whole surface of the back plate, and the hollowed-out portions are arranged in a staggered manner.

6. The flexible display screen according to any one of claims 1 to 4, wherein the hollowed-out portions are disposed in a partial area of the back plate, and the hollowed-out portions are arranged in a staggered manner.

7. The flexible display screen according to any one of claims 1 to 4, wherein the back plate is divided into a plurality of sections, each of the sections is provided with the hollowed-out portion, and the lengths of the hollowed-out portions of the plurality of sections are gradually increased.

8. A preparation method of a flexible display screen is characterized by comprising the following steps:

step S10, providing a back plate, wherein a plurality of hollowed-out parts are arranged on the back plate, each hollowed-out part comprises two first circular arcs with opposite openings and two transition lines connecting the two first circular arcs, and the column spacing between every two adjacent hollowed-out parts and the first curvature radius of the two first circular arcs meet a preset relationship; and

step S20, providing a display panel, including attaching the display panel on the backboard; and

and step S30, attaching a cover plate, including attaching the cover plate on the surface of the display panel far away from the back plate.

9. The method for manufacturing the flexible display screen according to claim 8, wherein the two transition lines comprise two straight lines or two second arcs with opposite openings or two third arcs with opposite openings.

10. A flexible display device comprising a flexible display screen according to any one of claims 1 to 7.