Foldable screen expansion device and electronic equipment

Abstract

The present invention provides a foldable screen expansion device and an electronic device, the foldable screen expansion device comprising: a foldable display screen, comprising a first display area, a second display area and a foldable display area, the foldable display area is located between the first display area and the second display area, and connects the first display area and the second display area; a middle frame, arranged on the back of the foldable display screen, and used to fix the foldable display screen, the middle frame comprising a first frame body and a second frame body, the first frame body is located on the back of the first display area, the second frame body is located on the back of the second display area, and a mobile phone slot is provided on the side of the first frame body away from the first display area; a front frame, arranged on the front of the foldable display screen, fixedly connected to the middle frame, and used to fix the foldable display screen; and a folding hinge, located on the back of the foldable display area, and connecting the first frame body and the second frame; wherein, when the foldable screen expansion device is in an unfolded state, the foldable display screen can receive a signal from a mobile phone in the mobile phone slot to perform screen projection display.

Description

Technical Field

[0001] The present application relates to the field of display, and in particular to a foldable screen expansion device and an electronic device. Background Art

[0002] When a foldable phone is in folded state, it can be used as a single-screen phone. When it is in unfolded state, the dual-screen display provides a larger display area and can be used as a tablet. The expandable display screen performance makes foldable phones popular with users.

[0003] However, the existing foldable mobile phones realize the folding function of the mobile phone by setting a folding area in the middle part of the flexible screen. In this way, the main screen and the sub-screen of the mobile phone have heavy device accessories, which makes the foldable mobile phone larger in size and heavier in weight, making it inconvenient to carry. Summary of the invention

[0004] The present invention provides a foldable screen expansion device and an electronic device to solve the problem that the existing foldable mobile phone is large in size and heavy in weight.

[0005] To solve the above problems, the technical solution provided by the present invention is as follows:

[0006] The present invention provides a foldable screen expansion device, the foldable screen expansion device comprising:

[0007] A folding display screen, comprising a first display area, a second display area and a folding display area, wherein the folding display area is located between the first display area and the second display area and connects the first display area and the second display area;

[0008] a middle frame, arranged on the back of the foldable display screen, used to fix the foldable display screen, the middle frame comprising a first frame body and a second frame body, the first frame body being located on the back of the first display area, the second frame body being located on the back of the second display area, and a mobile phone slot being provided on a side of the first frame body away from the first display area;

[0009] A front frame, disposed on the front side of the foldable display screen, fixedly connected to the middle frame, and used for fixing the foldable display screen; and

[0010] A folding hinge, the folding hinge is located on the back of the folding display area and connects the first frame and the second frame;

[0011] Among them, when the foldable screen expansion device is in the unfolded state, the foldable display screen can receive the signal of the mobile phone in the mobile phone slot and perform screen projection display.

[0012] Optionally, in some embodiments of the present invention, the middle frame further includes a battery, and the battery is located in the second frame body, and is used to provide power for the folding display screen; when the mobile phone is located in the mobile phone slot, the battery can also charge the mobile phone.

[0013] Optionally, in some embodiments of the present invention, the side wall of the mobile phone slot is a curved surface.

[0014] Optionally, in some embodiments of the present invention, the mobile phone card slot includes a first side wall, a second side wall and a third side wall, and the second side wall and the third side wall are respectively vertically connected to the first side wall; the first side wall is close to the folding hinge, and the second side wall and the third side wall are respectively perpendicular to the folding hinge; or, the second side wall is close to the folding hinge, and the first side wall is perpendicular to the folding hinge.

[0015] Optionally, in some embodiments of the present invention, the middle frame further includes a folding locking structure, the folding locking structure includes a locking point and a locking switch, the locking point and the locking switch can be locked and fixed, the locking point is located on the second frame body, and the locking switch is located on the first frame body.

[0016] Optionally, in some embodiments of the present invention, the first frame body further includes an out-of-screen protrusion, the out-of-screen protrusion is located on a side of the first frame body away from the mobile phone card slot and protrudes out of the display surface of the first display area, the card switch is provided on the side wall of the out-of-screen protrusion close to the first display area, and the card point is located on the side wall of the second frame body away from the folding hinge.

[0017] Optionally, in some embodiments of the present invention, the locking switch includes a first locking buckle, a second locking buckle and a locking spring, the first locking buckle is located in the outer protrusion of the screen and partially protrudes from the side wall, the locking spring is located in the outer protrusion of the screen and is connected to the side of the first locking buckle away from the side wall, the first locking buckle includes a locking groove, the second locking buckle is partially located in the locking groove, and can move up and down in the locking groove, so that under the action of the locking spring, the first locking buckle is driven to move in a direction away from or toward the locking spring, so that the first locking buckle partially protrudes from the side wall and engages with the locking point, or is completely retracted into the outer protrusion of the screen and separated from the locking point.

[0018] Optionally, in some embodiments of the present invention, the outer protrusion of the screen also includes an active pen limiting structure for fixing the active pen.

[0019] Optionally, in some embodiments of the present invention, the active pen limiting structure includes a fixed sleeve, a locking pin, a limiting spring, and a locking sleeve, the locking pin and the limiting spring are located in the fixed sleeve on a side away from the locking sleeve, the locking sleeve includes a locking groove and a pen tip locking groove, the locking groove can be fixedly connected to or detached from the locking pin, and the pen tip locking groove can fix the active pen.

[0020] In response, the present invention also provides an electronic device, including a mobile phone and the foldable screen expansion device described in any one of the embodiments of the present invention, wherein the mobile phone is located in a mobile phone slot of the foldable screen expansion device.

[0021] The present invention provides a foldable screen expansion device and an electronic device. When a large-screen display is required, a mobile phone is placed in the mobile phone slot, the foldable screen expansion device is unfolded, and the foldable display screen receives a signal from the mobile phone to perform screen projection display, thereby realizing the function of large-screen display. When a large-screen display is not required, the foldable screen expansion device is folded and stored, thereby realizing the large-screen display function of the mobile phone without increasing the volume and weight of the mobile phone, and is convenient for storage and carrying. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The technical solution and other beneficial effects of the present application will be made apparent by describing in detail the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0023] Figure 1 A schematic diagram of a first structure of a foldable screen expansion device provided by an embodiment of the present invention;

[0024] Figure 2 A second structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0025] Figure 3 A third structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0026] Figure 4 A fourth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0027] Figure 5 A fifth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0028] Figure 6 A sixth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0029] Figure 7 A seventh structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0030] Figure 8 An eighth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention;

[0031] Fig. 9 A working principle diagram of the active pen limiting structure provided by an embodiment of the present invention;

[0032] Fig.10 A ninth structural schematic diagram of a foldable screen expansion device provided by an embodiment of the present invention;

[0033] Fig.11 A tenth structural schematic diagram of the foldable screen expansion device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments and / or examples of the present invention. Obviously, the embodiments and / or examples described below are only part of the embodiments and / or examples of the present invention, rather than all the embodiments and / or examples. Based on the embodiments and / or examples in the present invention, all other embodiments and / or examples obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The directional terms mentioned in the present invention, such as [upper], [lower], [left], [right], [front], [back], [inner], [outer], [side], etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and understand the present invention, rather than to limit the present invention. The terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0036] In view of the problem that existing foldable mobile phones are large in size and heavy in weight, the present invention provides a foldable screen expansion device and an electronic device to solve the problem.

[0037] In one embodiment, see Figures 1 to 3 , Figure 1 A first structural schematic diagram of a foldable screen expansion device provided in an embodiment of the present invention is shown, specifically, an exploded diagram of the entire foldable screen expansion device; Figure 2 A second structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention is shown, specifically a first back three-dimensional structural schematic diagram of the foldable screen expansion device in an unfolded state; Figure 3FIG. 1 shows a third structural schematic diagram of a foldable screen expansion device provided by an embodiment of the present invention, specifically a second rear three-dimensional structural schematic diagram of a foldable screen expansion device in an unfolded state. Figures 1 to 3 As shown, the foldable screen expansion device provided by the embodiment of the present invention includes:

[0038] A folding display screen, comprising a first display area, a second display area and a folding display area, wherein the folding display area is located between the first display area and the second display area and connects the first display area and the second display area;

[0039] a middle frame, arranged on the back of the foldable display screen, used to fix the foldable display screen, the middle frame comprising a first frame body and a second frame body, the first frame body being located on the back of the first display area, the second frame body being located on the back of the second display area, and a mobile phone slot being provided on a side of the first frame body away from the first display area;

[0040] A front frame, disposed on the front side of the foldable display screen, fixedly connected to the middle frame, and used for fixing the foldable display screen; and

[0041] A folding hinge, the folding hinge is located on the back of the folding display area and connects the first frame and the second frame;

[0042] Among them, when the foldable screen expansion device is in the unfolded state, the foldable display screen can receive the signal of the mobile phone in the mobile phone slot and perform screen projection display.

[0043] The embodiment of the present invention is designed with a foldable screen expansion device having a foldable display screen and a mobile phone slot. When a large-screen display is required, the mobile phone is placed in the mobile phone slot, the foldable screen expansion device is unfolded, and the foldable display screen receives the signal of the mobile phone to perform screen projection display, thereby realizing the function of large-screen display; when the large-screen display is not required, the foldable screen expansion device is folded and stored, and while realizing the large-screen display function of the mobile phone, the volume and weight of the mobile phone do not need to be increased, and it is easy to store and carry.

[0044] Specifically, the front frame includes a first front frame and a second front frame, the first front frame and the second front frame are arranged opposite to each other and do not contact each other. The first front frame is arranged at the periphery of the first display area and is fixedly connected to the first frame body to fix the first display area; the second front frame is arranged at the periphery of the second display area and is fixedly connected to the second frame body to fix the second display area.

[0045] The folding hinge includes two rotating shafts arranged opposite to each other, two connecting plates arranged opposite to each other, and a rotating shaft cover. Among them, one side of one connecting plate is connected to the first middle frame, and the other side is connected to the first display area; one side of another connecting plate is connected to the second middle frame, and the other side is connected to the second display area. The two rotating shafts are respectively connected to the two ends of the two connecting plates, and the rotating shaft cover is correspondingly arranged on the back of the folding display area and located on the side of the connecting plate away from the folding display screen. The two ends of the rotating shaft cover are respectively connected to the two rotating shafts, and the two sides are respectively connected to the first middle frame and the second middle frame. By rotating and folding the folding hinge, the folding and unfolding functions of the foldable screen expansion device can be realized.

[0046] In one embodiment, the foldable screen expansion device may further include a cover plate, which is arranged on a side of the second frame away from the foldable display screen, and is used to protect the foldable screen expansion device.

[0047] The middle frame also includes a battery, which is located in the second frame and is used to provide power for the folding display screen. When the mobile phone is in the mobile phone slot, the battery can also charge the mobile phone, thereby extending the battery life of the mobile phone.

[0048] In one embodiment, see Figure 2 and Figure 3 The mobile phone slot includes a first side wall, a second side wall and a third side wall, and the second side wall and the third side wall are respectively vertically connected to the first side wall. The first side wall, the second side wall and the three sides are surrounded, leaving one side as an opening for placing the mobile phone. The mobile phone is placed into the mobile phone slot through the opening, and the size of the mobile phone slot is not less than the size of the mobile phone. In one embodiment, the display surface of the mobile phone is placed into the mobile phone slot facing the bottom of the mobile phone slot, such as Figure 2 As shown; this can reduce damage to the mobile phone screen during use or carrying.

[0049] In one embodiment, the first side wall is close to the folding hinge, and the second side wall and the third side wall are respectively perpendicular to the folding hinge, that is, the first side wall corresponds to the right side of the mobile phone at a front angle, the second side wall corresponds to the top side of the mobile phone at a front angle, and the third side wall corresponds to the bottom side of the mobile phone at a front angle, and the third side wall is provided with a first opening to avoid the data cable connection port of the mobile phone, such as Figure 2As shown; in this way, the mobile phone can be pushed into the mobile phone slot from the right side, and the pushing distance is short, which is convenient for putting in and taking out the mobile phone. In another embodiment, the second side wall is close to the folding hinge, and the first side wall is perpendicular to the folding hinge, that is, the first side wall corresponds to the top side of the mobile phone at a front viewing angle, and the second side wall and the third side wall respectively correspond to the left and right sides of the mobile phone at a front viewing angle, so that the mobile phone can be pushed into the mobile phone slot from the top side, and there is no need to set an opening on the side wall to avoid the data cable connection port. Furthermore, when the mobile phone is placed in the mobile phone slot and the foldable screen expansion device is unfolded for display, the foldable screen expansion device can share the hardware functions of the mobile phone, such as camera, speaker, etc., which can maximize the reduction of the volume and weight of the foldable screen expansion device for easy carrying.

[0050] In one embodiment, the longitudinal sections of the first side wall, the second side wall and the third side wall are all arc-shaped, and the size of the arc matches the corresponding side of the mobile phone; in this way, there is no need to set an additional limiting structure, and the three sides of the mobile phone card slot realize the arc limiting function of the mobile phone. The arc limiting not only satisfies the card-fitting limiting of the mobile phone, but also protects the side of the mobile phone to the maximum extent. Please refer to Figure 3 .

[0051] In one embodiment, see Figures 4 to 6 , Figure 4 A fourth structural schematic diagram of a foldable screen expansion device provided by an embodiment of the present invention is shown, Figure 4 (a) is a schematic diagram of a first side perspective structure of the foldable screen expansion device in a semi-folded state. Figure 4 (b) is a schematic diagram of a second side stereoscopic structure of the foldable screen expansion device in a semi-folded state; Figure 5 A fifth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention is shown, Figure 5 (a) is a schematic diagram of a first three-dimensional structure of the folding positioning structure of the foldable screen expansion device. Figure 5 (b) is a schematic diagram of a second three-dimensional structure of the folding positioning structure of the foldable screen expansion device. Figure 5 (c) is a schematic diagram of a third three-dimensional structure of the folding positioning structure of the foldable screen expansion device; Figure 6 FIG. 6 is a sixth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention, specifically a partial enlarged schematic diagram of the foldable screen expansion device in a folded state. Figures 4 to 6As shown, the middle frame also includes a folding latch structure, and the folding latch structure includes a latching point and a latching switch, and the latching point and the latching switch can be locked and fixed, and the latching point is located on the second frame, and the latching switch is located on the first frame, or the latching point is located on the first frame, and the latching switch is located on the second frame. By respectively providing the latching point and the latching switch on the first frame and the second frame, when the foldable screen expansion device is folded, the first frame and the second frame are locked and fixed by the folding latch structure, thereby improving the stability of the foldable screen expansion device in the folded state and reducing the risk of damage to the folding display screen.

[0052] In one embodiment, the first frame further comprises a screen-outside convex portion, the screen-outside convex portion is located on a side of the first frame away from the mobile phone card slot and protrudes out of the display surface of the first display area, the card switch is arranged on a side wall of the screen-outside convex portion close to the first display area, and the card point is located on a side wall of the second frame away from the folding hinge, such as Figure 4 Specifically, Figure 5 and Figure 6 As shown, the locking switch includes a first locking buckle, a second locking buckle and a locking spring. The first locking buckle is located in the outer convex portion of the screen and partially protrudes from the side wall of the outer convex portion of the screen, the locking spring is located in the outer convex portion of the screen and connected to the side of the first locking buckle away from the side wall, and the second locking buckle is located on the side of the first locking buckle away from the mobile phone locking slot and connected to the first locking buckle.

[0053] The first buckle protruding from the side wall includes a first inclined surface facing away from the first display area, and the first inclined surface facilitates the first buckle to engage or disengage with the locking point; the first buckle located in the outer convex part of the screen includes a locking groove with an opening facing away from the mobile phone locking slot, the locking groove includes a second inclined surface facing away from the mobile phone locking slot and the locking spring, the second buckle is located in the outer convex part of the screen and includes a third inclined surface facing the second inclined surface, the second buckle is partially located in the locking groove, and the second inclined surface and the third inclined surface are in contact with each other. The outer convex part of the screen also includes a locking contact port facing away from one side of the mobile phone locking slot, and the locking port exposes the second buckle. The second buckle can move in a direction toward or away from the mobile phone locking slot under the action of an external force, thereby driving the first buckle to move in a direction toward and away from the locking spring, so that the first buckle is completely received in the outer convex part of the screen and separated from the locking point, or partially protrudes from the outer convex part of the screen and engages with the locking point.

[0054] In one embodiment, see Figures 7 and 8 , Figure 7A seventh structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention is shown, Figure 7 (a) is a first partial disassembly diagram of the foldable screen expansion device. Figure 7 (b) is specifically a first partial disassembly diagram of the foldable screen expansion device; Figure 8 An eighth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention is shown, Figure 8 (a) shows a schematic structural diagram of an active pen limiting structure provided by an embodiment of the present invention, Figure 8 (b) shows a disassembled view of the active pen limiting structure provided by an embodiment of the present invention, Figure 8 (c) shows Figure 8 A partial enlarged schematic diagram of (b). Figure 7 and Figure 8 As shown, the outer convex part of the screen also includes an active pen limiting structure, and the active pen limiting structure is used to fix the active pen. The active pen limiting structure includes a fixed sleeve, a locking pin, a limiting spring, and a locking sleeve. The locking pin and the limiting spring are located on the side of the fixed sleeve away from the locking sleeve. The locking sleeve includes a locking slot and a pen tip locking slot. The locking slot can be fixedly connected to or detached from the locking pin. A friction strip is provided in the pen tip locking slot, which corresponds to the friction strip of the active pen, so that the active pen will not fall off when pushed into the locking sleeve.

[0055] For details, please refer to Fig. 9 , Fig. 9 FIG. 2 shows a working principle diagram of the active pen limiting structure provided by an embodiment of the present invention. Fig. 9 As shown in (a), when the active pen is located outside the active pen limiting structure, the locking pin is located at the bottom of the locking slot of the locking sleeve; Fig. 9 As shown in (b), when the active pen needs to be fixed, the active pen is inserted into the locking sleeve, and the locking sleeve is pushed to slide downward, and the locking pin slides along the bottom of the locking slot to the top, and the path is as shown in the arrow direction in the figure; Fig. 9 As shown in (c), when the active pen is pressed to the bottom, the pressing of the active pen is stopped, and the limit spring pushes the locking sleeve to slide outward. At this moment, the locking pin slides along the locking slot to the limit position, so that the locking sleeve cannot be completely pushed out. The path is shown in the direction of the arrow in the figure; Fig. 9 As shown in (d), when the active pen needs to be taken out, the active pen is pushed again, and the active pen pushes the locking sleeve, and the locking pin slides to a fixed position and hits the upper inclined surface of the locking slot, and the path is shown in the direction of the arrow in the figure; Fig. 9As shown in (e), stop pushing the active pen, and the limit spring pushes the locking sleeve to slide outward, so that the locking pin slides out to the initial position along the position shown in the figure, and the active pen is pushed out of the body, and can be pulled out from the locking sleeve for use.

[0056] Please refer to Fig.10 and Fig.11 , Fig.10 A ninth structural schematic diagram of the foldable screen expansion device provided by an embodiment of the present invention is shown. Fig.10 (a) is a schematic diagram of the front three-dimensional structure of the foldable screen expansion device in the unfolded state. Fig.10 (b) is a schematic diagram of the back three-dimensional structure of the foldable screen expansion device in the unfolded state; Fig.11 A tenth structural schematic diagram of a foldable screen expansion device provided by an embodiment of the present invention is shown, Fig.11 (a) is a schematic diagram of the first three-dimensional structure of the foldable screen expansion device in the folded state. Fig.11 (b) is a schematic diagram of the second side three-dimensional structure of the foldable screen expansion device in the folded state. Fig.11 (c) is a schematic diagram of the third side three-dimensional structure of the foldable screen expansion device in the folded state. Fig.10 As shown, when a large-screen display is needed, the mobile phone is placed in the mobile phone slot, the foldable screen expansion device is unfolded, and the foldable display screen receives the signal of the mobile phone to perform screen projection display, thereby realizing the function of large-screen display; Fig.11 As shown, when a large screen display is not needed, the foldable screen expansion device is folded for easy storage and carrying.

[0057] In response, an embodiment of the present invention further provides an electronic device, which includes the foldable screen expansion device described in any embodiment of the present invention and a mobile phone, and the mobile phone is located in a mobile phone slot of the foldable screen expansion device.

[0058] In summary, the embodiments of the present invention provide a foldable screen expansion device and an electronic device. When a large-screen display is required, the mobile phone is placed in the mobile phone slot, the foldable screen expansion device is unfolded, and the foldable display screen receives the signal of the mobile phone to perform screen projection display to realize the function of large-screen display. When a large-screen display is not required, the foldable screen expansion device is folded and stored. While realizing the large-screen display function of the mobile phone, the volume and weight of the mobile phone do not need to be increased, and it is easy to store and carry.

[0059] The foldable screen expansion device and electronic device provided in the embodiments of the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A foldable screen expansion device, characterized in that: include: A folding display screen, comprising a first display area, a second display area and a folding display area, wherein the folding display area is located between the first display area and the second display area and connects the first display area and the second display area; a middle frame, arranged on the back of the foldable display screen, used to fix the foldable display screen, the middle frame comprising a first frame body and a second frame body, the first frame body being located on the back of the first display area, the second frame body being located on the back of the second display area, and a mobile phone slot being provided on a side of the first frame body away from the first display area; The mobile phone slot includes a first side wall, a second side wall and a third side wall, wherein the second side wall and the third side wall are respectively connected vertically to the first side wall, so that the first side wall, the second side wall and the third side wall form a three-sided surround, leaving one side as a mobile phone placement opening, and the mobile phone is placed in the mobile phone slot through the placement opening; A front frame, disposed on the front side of the foldable display screen, fixedly connected to the middle frame, and used for fixing the foldable display screen; as well as A folding hinge, the folding hinge is located on the back of the folding display area and connects the first frame and the second frame; Wherein, when the foldable screen expansion device is in the unfolded state, the foldable display screen can receive the signal of the mobile phone in the mobile phone slot to perform screen projection display; The middle frame further includes a folding latch structure, the folding latch structure includes a latching point and a latching switch, the latching point and the latching switch can be engaged and fixed, the latching point is located on the second frame body, and the latching switch is located on the first frame body; The first frame also includes an outer screen protrusion, which is located on a side of the first frame away from the mobile phone card slot and protrudes out of the display surface of the first display area. The card switch is arranged on the side wall of the outer screen protrusion close to the first display area, and the card point is located on the side wall of the second frame away from the folding hinge.

2. The foldable screen expansion device according to claim 1, characterized in that: The middle frame also includes a battery, which is located in the second frame and is used to provide power for the folding display screen; when the mobile phone is located in the mobile phone slot, the battery can also charge the mobile phone.

3. The foldable screen expansion device according to claim 1, characterized in that: The side wall of the mobile phone slot is a curved surface.

4. The foldable screen expansion device according to claim 1, characterized in that: The first side wall is close to the folding hinge, and the second side wall and the third side wall are respectively perpendicular to the folding hinge; or, the second side wall is close to the folding hinge, and the first side wall is perpendicular to the folding hinge.

5. The foldable screen expansion device according to claim 1, characterized in that: The locking switch includes a first locking buckle, a second locking buckle and a locking spring, the first locking buckle is located in the outer protrusion of the screen and partially protrudes from the side wall, the locking spring is located in the outer protrusion of the screen and is connected to the side of the first locking buckle away from the side wall, the first locking buckle includes a locking groove, the second locking buckle is partially located in the locking groove, and can move up and down in the locking groove, so that under the action of the locking spring, the first locking buckle is driven to move in a direction away from or toward the locking spring, so that the first locking buckle partially protrudes from the side wall and engages with the locking point, or is completely retracted into the outer protrusion of the screen and separated from the locking point.

6. The foldable screen expansion device according to claim 1, characterized in that: The outer convex portion of the screen also includes an active pen limiting structure for fixing the active pen.

7. The foldable screen expansion device according to claim 6, characterized in that: The active pen limiting structure includes a fixed sleeve, a locking pin, a limiting spring, and a locking sleeve. The locking pin and the limiting spring are located in the fixed sleeve on a side away from the locking sleeve. The locking sleeve includes a locking groove and a pen tip locking groove. The locking groove can be fixedly connected to or detached from the locking pin, and the pen tip locking groove can fix the active pen.

8. An electronic device, characterized in that: It comprises the foldable screen expansion device and a mobile phone as described in any one of claims 1 to 7, wherein the mobile phone is located in a mobile phone slot of the foldable screen expansion device.

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