Headrest adjusting structure and sofa

Abstract

The utility model relates to the field of furniture, and discloses a headrest adjusting structure and a sofa, the headrest adjusting structure comprises an inner sleeve, an outer sleeve, a guide rod and a support, the support is used for being fixedly connected with a headrest, the guide rod extends along the vertical direction, the inner sleeve is inserted into the outer sleeve, and the outer sleeve is inserted into the inner sleeve. The inner sleeve and the outer sleeve are connected through threads, a first flange is arranged at the top of the inner sleeve and arranged outside the outer sleeve, the outer diameter of the first flange is larger than the inner diameter of the outer sleeve, the guide rod is fixed to the support and penetrates through the inner sleeve, and the guide rod is fixed to the support and penetrates through the outer sleeve. And the guide rod is connected with the outer sleeve through a connecting piece. In addition, the sofa comprises the headrest adjusting structure. The height of the headrest can be adjusted in a stepless mode, and the height of the headrest can be adjusted flexibly.

Description

Technical Field

[0001] The utility model relates to the field of sofas, in particular to a headrest adjustment structure and a sofa. Background Art

[0002] Currently, sofa headrests are usually directly plugged into holes reserved on the top surface of the sofa backrest. The bracket on the sofa headrest is provided with multiple slots, and a tension spring buckle for engaging the above slots is installed on the sofa backrest. The user can adjust the height of the headrest by adjusting the position of the tension spring buckle. However, the height of the headrest is limited by the distance between adjacent slots, which makes it difficult for some people to adjust the height of the headrest to a suitable height. Utility Model Content

[0003] The technical problem to be solved by the utility model is to solve at least one of the technical problems mentioned above.

[0004] The solution of the utility model to solve the technical problem is:

[0005] A headrest adjustment structure comprises an inner sleeve, an outer sleeve, a guide rod and a bracket, wherein the bracket is used to be fixedly connected to the headrest, the guide rod extends vertically, the inner sleeve is inserted into the outer sleeve, the inner sleeve and the outer sleeve are connected by threads, a first flange is provided on the top of the inner sleeve, the first flange is arranged outside the outer sleeve, the outer diameter of the first flange is larger than the inner diameter of the outer sleeve, the guide rod is fixed on the bracket, the guide rod is inserted into the inner sleeve, and the guide rod is connected to the outer sleeve by a connecting piece.

[0006] As a further improvement of the above technical solution, the connecting member includes a tension spring, one end of the tension spring is connected to the outer sleeve, and the other end of the tension spring is connected to the guide rod.

[0007] As a further improvement of the above technical solution, the connecting member also includes a connecting plate, a connecting hole is opened on the connecting plate, a second flange extends outward from the lower end of the outer sleeve, the outer sleeve is inserted into the connecting hole, the connecting plate is arranged above the second flange, the second flange is used to abut against the connecting plate, one end of the tension spring is fixedly connected to the connecting plate, and the other end of the tension spring is arranged below the second flange and fixedly connected to the guide rod.

[0008] As a further improvement of the above technical solution, the tension spring includes a first tension spring, a connecting arm and a second tension spring, and the connecting piece also includes a clamp, two of the clamps are provided, and the lower end of the guide rod is spaced apart by two limiting grooves, and the clamp is buckled in the limiting grooves, and the clamp and the limiting grooves are provided in a one-to-one correspondence, the second tension spring is sleeved on the guide rod, and the second tension spring is provided between the two clamps, and the two clamps respectively limit the upper and lower ends of the second tension spring, the first tension spring and the second tension spring are connected by a connecting arm, the first tension spring is provided on the outside of the guide rod, and the first tension spring is fixedly connected to the connecting plate.

[0009] As a further improvement of the above technical solution, two guide rods are provided, and the two guide rods are respectively provided on the left and right sides of the bracket, and the guide rods, the outer sleeve, the inner sleeve and the connecting piece are respectively provided in one-to-one correspondence.

[0010] As a further improvement of the above technical solution, the guide rods, outer sleeves, inner sleeves and connecting pieces on the left and right sides of the bracket are respectively arranged in a mirror-image manner to each other.

[0011] As a further improvement of the above technical solution, the bracket includes a mounting rod and a locking clip, the guide rod is arranged at the end of the mounting rod, the guide rod and the mounting rod are fixedly connected, the locking clip is clamped on the mounting rod, and the locking clip is used to install a sofa headrest.

[0012] As a further improvement of the above technical solution, the bracket also includes a limit block, which is arranged in a U shape, and the two ends of the U-shaped limit block are respectively fixed on the mounting rod, and the locking clip is arranged between the two ends of the U-shaped limit block.

[0013] As a further improvement of the above technical solution, the locking clip includes a first mounting plate and a second mounting plate, the first mounting plate including a first front plate, a second front plate and a third front plate connected in sequence from top to bottom, the second mounting plate including a first rear plate, a second rear plate and a third rear plate connected in sequence from top to bottom, the third front plate is arranged in a C-shape, the second front plate extends vertically, the lower end of the second front plate is fixedly connected to the C-shaped third front plate, the first front plate is arranged above the second front plate, the second front plate abuts against the second rear plate and is fixed by screws, and the first front plate and the first rear plate are arranged at intervals; the first front plate, the second front plate and the third front plate are respectively mirror-arranged with the first rear plate, the second rear plate and the third rear plate in one-to-one correspondence, so that the third front plate and the third rear plate clamp the mounting rod, and the first front plate and the first rear plate are used to install a headrest.

[0014] The utility model also provides a sofa, which includes a backrest and a headrest adjustment structure in any of the above technical solutions, wherein an opening is provided on the top surface of the backrest, a channel extending in the up-down direction is formed in the opening, the outer sleeve is arranged in the channel, the channel limits the rotation of the outer sleeve, the inner sleeve is arranged outside the channel, a limiting frame is provided on the backrest, the limiting frame limits the first flange along the axial and radial directions of the inner sleeve to limit the up-and-down movement of the first flange.

[0015] The beneficial effects of the utility model are as follows: the headrest of the sofa can be installed on the bracket, the outer diameter of the first flange is larger than the inner diameter of the outer sleeve, and the inner sleeve can be limited to limit the depth of the inner sleeve moving downward. The guide rod is inserted into the inner sleeve from top to bottom, and the guide rod is connected to the outer sleeve through a connector, so that the user can adjust the depth of the guide rod inserted into the inner sleeve from top to bottom by adjusting the length of the threaded connection between the outer sleeve and the inner sleeve, that is, adjust the height of the guide rod. When in use, the inner sleeve can be limited on the external sofa, and only the freedom of the inner sleeve to rotate around its own axis is retained, while the outer sleeve is limited by the external sofa to rotate around its own axis. When the height of the bracket needs to be adjusted, the height of the outer sleeve can be adjusted by rotating the inner sleeve under the threaded cooperation of the inner sleeve and the outer sleeve. Since the outer sleeve is connected to the guide rod through a connector, the height of the guide rod is adjusted, and the height of the bracket on the guide rod is adjusted. The utility model can steplessly adjust the height of the bracket, and the height adjustment is flexible and very convenient to use, and can be adapted to a plurality of people of different heights. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a front view of the headrest adjustment structure of the utility model;

[0017] Figure 2 This utility model is Figure 1 Axonometric section view at CC in ;

[0018] Figure 3 It is an axonometric diagram of the headrest adjustment structure of the utility model.

[0019] In the accompanying drawings: 1-inner sleeve, 11-first flange, 2-outer sleeve, 21-second flange, 3-guide rod, 4-bracket, 41-first front plate, 42-second front plate, 43-third front plate, 44-first rear plate, 45-second rear plate, 47-mounting rod, 51-first tension spring, 52-second tension spring, 53-connecting arm, 54-connecting plate, 6-clamp, 7-limiting block. DETAILED DESCRIPTION

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the above briefly describes the drawings required for use in the description of the embodiments. Obviously, the drawings described are only part of the embodiments of the present invention, not all of them. Those skilled in the art can also obtain other design solutions and drawings based on these drawings without creative work.

[0021] The following will clearly and completely describe the concept, specific structure and technical effects of the utility model in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the utility model. In addition, all the connection / connection relationships mentioned in the text do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the utility model can be combined interchangeably without conflicting with each other.

[0022] Reference Figures 1 to 3 A headrest adjustment structure comprises an inner sleeve 1, an outer sleeve 2, a guide rod 3 and a bracket 4, the bracket 4 is used to be fixedly connected to the headrest, the guide rod 3 extends vertically, the inner sleeve 1 is inserted in the outer sleeve 2, the inner sleeve 1 and the outer sleeve 2 are connected by threads, the top of the inner sleeve 1 is provided with a first flange 11, the first flange 11 is arranged outside the outer sleeve 2, the outer diameter of the first flange 11 is larger than the inner diameter of the outer sleeve 2, the guide rod 3 is fixed on the bracket 4, the guide rod 3 is inserted in the inner sleeve 1, and the guide rod 3 is connected to the outer sleeve 2 by a connecting piece.

[0023] As can be seen from the above, the headrest of the sofa can be installed on the bracket 4, and the outer diameter of the first flange 11 is larger than the inner diameter of the outer sleeve 2, so that the inner sleeve 1 can be limited to limit the depth of the inner sleeve 1 moving downward. The guide rod 3 is inserted into the inner sleeve 1 from top to bottom, and the guide rod 3 is connected to the outer sleeve 2 through a connector, so that the user can adjust the depth of the guide rod 3 inserted into the inner sleeve 1 from top to bottom by adjusting the length of the threaded connection between the outer sleeve 2 and the inner sleeve 1, that is, adjust the height of the guide rod 3. When in use, the inner sleeve 1 can be limited on the external sofa, and only the freedom of the inner sleeve 1 to rotate around its own axis is retained, while the outer sleeve 2 is limited by the external sofa to rotate around its own axis. When the height of the bracket 4 needs to be adjusted, the height of the outer sleeve 2 can be adjusted by rotating the inner sleeve 1 under the threaded cooperation of the inner sleeve 1 and the outer sleeve 2. Since the outer sleeve 2 is connected to the guide rod 3 through a connector, the height of the guide rod 3 is adjusted, and the height of the bracket 4 on the guide rod 3 is adjusted. The utility model can perform stepless adjustment on the height of the bracket 4, has flexible adjustment, is very convenient to use, and can be adapted to people of different heights.

[0024] The bracket 4 is used to install the headrest. In order to make the headrest give the user a more comfortable experience during use, for example, after the user's head is pressed down on the headrest, the headrest can play a certain buffering role on the user's head. To this end, in some embodiments, the connecting member includes a tension spring, one end of which is connected to the outer sleeve 2, and the other end of the tension spring is connected to the guide rod 3. The structure is simple and convenient to set up. Since the bracket 4 is used to install the headrest of the sofa, when the bracket 4 is pressed down, the guide rod 3 moves downward under the downward pressure. In the process of the guide rod 3 moving downward, the spring force of the tension spring needs to be overcome. It can be obtained from Hooke's law that the greater the elongation of the tension spring, the greater the tension generated. Therefore, the more the guide rod 3 moves downward, the greater the spring force of the tension spring that needs to be overcome, which can effectively play a buffering role on the user's head.

[0025] In order to facilitate the installation and maintenance of the tension spring. In some embodiments, the connector also includes a connecting plate 54, a connecting hole is opened on the connecting plate 54, a second flange 21 extends outward from the lower end of the outer sleeve 2, the outer sleeve 2 is inserted into the connecting hole, the connecting plate 54 is arranged above the second flange 21, the second flange 21 is used to abut against the connecting plate 54, one end of the tension spring is fixedly connected to the connecting plate 54, and the other end of the tension spring is arranged below the second flange 21 and fixedly connected to the guide rod 3. When in use, the upper end of the tension spring is installed on the connecting plate 54, and the lower end of the tension spring is installed on the guide rod 3. The connecting plate 54 is sleeved on the outer sleeve 2 through the connecting hole, and the lower end of the connecting plate 54 is limited by the second flange 21 to limit the distance of the downward movement of the connecting plate 54. The structure is simple and convenient to set up. The connecting plate 54 and the outer sleeve 2 are in a sleeve connection relationship, and it is very convenient to install or disassemble, so that the upper end of the tension spring can be installed or disassembled more easily.

[0026] Further, in order to facilitate the installation or removal of the lower end of the tension spring, in some embodiments, the tension spring includes a first tension spring 51, a connecting arm 53 and a second tension spring 52, the connecting member also includes a clamp 6, two clamps 6 are provided, the lower end of the guide rod 3 is spaced apart by two limiting grooves, the clamp 6 is buckled in the limiting grooves, the clamp 6 and the limiting grooves are provided in a one-to-one correspondence, the second tension spring 52 is sleeved on the guide rod 3, the second tension spring 52 is provided between the two clamps 6, the two clamps 6 respectively limit the upper and lower ends of the second tension spring 52, the first tension spring 51 and the second tension spring 52 are connected by the connecting arm 53, the first tension spring 51 is provided outside the guide rod 3, and the first tension spring 51 is fixedly connected to the connecting plate 54. The two clamps 6 are respectively clamped in the two limiting grooves to limit the second tension spring 52. The second tension spring 52 is located at the lower end of the tension spring. When the lower end of the tension spring needs to be disassembled, the clamp 6 in the limiting groove can be disassembled to disassemble the second tension spring 52, which is very convenient to use.

[0027] In addition, the first tension spring 51 is not sleeved on the guide rod 3, but is arranged outside the guide rod 3. When the first tension spring 51 stretches or contracts, the possibility of the first tension spring 51 colliding with the guide rod 3 is effectively reduced, and the possibility of abnormal noise when the bracket 4 moves up and down is reduced.

[0028] The first tension spring 51 and the second tension spring 52 are connected by a connecting arm 53. It can be understood that the first tension spring 51, the second tension spring 52 and the connecting arm 53 are wound by the same metal wire, that is, the metal wire is first wound around the first tension spring 51, the end of the first tension spring 51 extends out of the connecting arm 53, and then the second tension spring 52 is wound around the end of the connecting arm 53.

[0029] In order to make the bracket 4 more stable during the up and down movement, in some embodiments, two guide rods 3 are provided, and the two guide rods 3 are respectively provided on the left and right sides of the bracket 4, and the guide rods 3, the outer sleeve 2, the inner sleeve 1 and the connecting member are respectively provided in a one-to-one correspondence. The structure is simple and convenient to set up. Through the setting of the structure, the two guide rods 3 are respectively plugged into the inner sleeve 1 in a one-to-one correspondence, which can effectively limit the freedom of the guide rod 3 to rotate around its own axis, prevent the bracket 4 from rotating around the axis of the guide rod 3, and make its structure stable.

[0030] Furthermore, in order to facilitate installation and production, in some embodiments, the guide rod 3, the outer sleeve 2, the inner sleeve 1 and the connecting piece on the left and right sides of the bracket 4 are respectively arranged in a mirror image with each other.

[0031] The bracket 4 is used to install the headrest. In some embodiments, the bracket 4 includes a mounting rod 47 and a locking clip. The guide rod 3 is arranged at the end of the mounting rod 47. The guide rod 3 and the mounting rod 47 are fixedly connected. The locking clip is clamped on the mounting rod 47. The locking clip is used to install the sofa headrest. The structure is simple and convenient to set. The headrest can be installed on the locking clip. The locking clip is clamped on the mounting rod 47. In this way, it is convenient for the user to adjust the position of the locking clip locked on the mounting rod 47, thereby adjusting the position of the headrest.

[0032] In some embodiments, both ends of the mounting rod 47 are connected to the guide rod 3, and the two guide rods 3 are respectively fixedly connected to the two ends of the mounting rod 47. The upper ends of the two guide rods 3 are connected to the two ends of the guide mounting rod 47. For example, the connection between the guide rod 3 and the mounting rod 47 can be achieved by welding, screw fixing, bending and forming, etc.

[0033] In order to limit the position of the locking clip clamped on the mounting rod 47, in some embodiments, the bracket 4 further includes a limit block 7, the limit block 7 is arranged in a U shape, the two ends of the U-shaped limit block 7 are respectively fixed on the mounting rod 47, and the locking clip is arranged between the two ends of the U-shaped limit block 7. Optionally, the limit block 7 is arranged in a U shape, and its two ends are respectively welded and fixed to the mounting rod 47. In this way, the locking clip is arranged between the two ends of the limit block 7, and the two ends of the limit block 7 are used to limit the locking clip along the axial direction of the mounting rod 47. In addition, the limit block 7 can also be used to limit the rotation of the locking clip around the axis of the mounting rod 47, so that the headrest is installed after the locking clip, and the structure is stable, so as to prevent the headrest from rotating excessively and failing to support the user's head.

[0034] The locking clip is used to clamp on the mounting rod 47. To this end, in some embodiments, the locking clip includes a first mounting plate and a second mounting plate, the first mounting plate includes a first front plate 41, a second front plate 42 and a third front plate 43 connected in sequence from top to bottom, the second mounting plate includes a first rear plate 44, a second rear plate 45 and a third rear plate connected in sequence from top to bottom, the third front plate 43 is arranged in a C shape, the second front plate 42 extends vertically, the lower end of the second front plate 42 is fixedly connected to the C-shaped third front plate 43, and the first A front plate 41 is arranged above the second front plate 42, the second front plate 42 abuts against the second rear plate 45 and is fixed by screws, the first front plate 41 and the first rear plate 44 are arranged at intervals; the first front plate 41, the second front plate 42 and the third front plate 43 are mirror-imaged to the first rear plate 44, the second rear plate 45 and the third rear plate, respectively, one by one, so that the third front plate 43 and the third rear plate clamp the mounting rod 47, and the first front plate 41 and the first rear plate 44 are used to install the headrest. The structure is simple and easy to set up. The second front plate 42 and the second rear plate 45 are fixed by screws. When disassembly is required, the second front plate 42 and the second rear plate 45 can be loosened by loosening the screws, which is very convenient to use. After the second front plate 42 and the second rear plate 45 are connected and fixed by screws, a clamping channel is formed between the C-shaped third front plate 43 and the third rear plate, and the mounting rod 47 is located in the clamping channel. The first front plate 41 and the first rear plate 44 are arranged at intervals so that the headrest can be fixed by using the first front plate 41 and the first rear plate 44. When the headrest is fixed to the first front plate 41 and the first rear plate 44, for example, a blind hole adapted to the first front plate 41 and the first rear plate 44 can be opened on the bottom surface of the headrest so that the first front plate 41 and the first rear plate 44 can be inserted into the blind hole. For another example, the headrest can be arranged between the first front plate 41 and the first rear plate 44, and the headrest, the first front plate 41 and the first rear plate 44 can be fixed by screws.

[0035] The utility model also provides a sofa, which includes a backrest and a headrest adjustment structure in any of the above-mentioned embodiments, wherein an opening is provided on the top surface of the backrest, a channel extending in the up-down direction is formed in the opening, the outer sleeve 2 is arranged in the channel, the channel limits the rotation of the outer sleeve 2, the inner sleeve 1 is arranged outside the channel, a limiting frame is provided on the backrest, the limiting frame limits the first flange 11 along the axial and radial directions of the inner sleeve 1 to limit the up-and-down movement of the first flange 11.

[0036] When in use, the inner sleeve 1 is limited in axial and radial freedom by the limit frame on the backrest, and only the rotational freedom of the inner sleeve 1 is retained, so that the user can rotate it and adjust the thread matching length of the outer sleeve 2 and the inner sleeve 1.

[0037] Since the above content has been described with respect to the headrest adjustment structure, those skilled in the art should be able to understand it in conjunction with the drawings in the specification, and therefore the headrest adjustment structure will not be described in detail here.

[0038] The preferred implementation modes of the present invention are specifically described above, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention, and these equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A headrest adjustment structure, characterized in that: The invention comprises an inner sleeve (1), an outer sleeve (2), a guide rod (3) and a bracket (4), wherein the bracket (4) is used for being fixedly connected to the headrest, the guide rod (3) extending vertically, the inner sleeve (1) being inserted into the outer sleeve (2), the inner sleeve (1) and the outer sleeve (2) being connected by threads, the top of the inner sleeve (1) being provided with a first flange (11), the first flange (11) being arranged outside the outer sleeve (2), the outer diameter of the first flange (11) being larger than the inner diameter of the outer sleeve (2), the guide rod (3) being fixed on the bracket (4), the guide rod (3) being inserted into the inner sleeve (1), and the guide rod (3) being connected to the outer sleeve (2) by a connecting piece.

2. The headrest adjustment structure according to claim 1, characterized in that: The connecting member comprises a tension spring, one end of which is connected to the outer sleeve (2), and the other end of which is connected to the guide rod (3).

3. The headrest adjustment structure according to claim 2, characterized in that: The connecting member also includes a connecting plate (54), a connecting hole is formed on the connecting plate (54), a second flange (21) extends outward from the lower end of the outer sleeve (2), the outer sleeve (2) is inserted into the connecting hole, the connecting plate (54) is arranged above the second flange (21), and the second flange (21) is used to abut against the connecting plate (54), one end of the tension spring is fixedly connected to the connecting plate (54), and the other end of the tension spring is arranged below the second flange (21) and fixedly connected to the guide rod (3).

4. The headrest adjustment structure according to claim 3, characterized in that: The tension spring comprises a first tension spring (51), a connecting arm (53) and a second tension spring (52). The connecting member further comprises a clamp (6). Two clamps (6) are provided. The lower end of the guide rod (3) is provided with two limiting grooves. The clamp (6) is buckled in the limiting grooves. The clamp (6) and the limiting grooves are provided in a one-to-one correspondence. The second tension spring (52) is sleeved on the guide rod (3). The second tension spring (52) is provided between the two clamps (6). The two clamps (6) respectively limit the upper and lower ends of the second tension spring (52). The first tension spring (51) and the second tension spring (52) are connected via the connecting arm (53). The first tension spring (51) is provided on the outer side of the guide rod (3). The first tension spring (51) is fixedly connected to the connecting plate (54).

5. The headrest adjustment structure according to claim 1, characterized in that: Two guide rods (3) are provided, and the two guide rods (3) are respectively provided on the left and right sides of the bracket (4), and the guide rods (3), the outer sleeve (2), the inner sleeve (1) and the connecting piece are respectively provided in a one-to-one correspondence.

6. The headrest adjustment structure according to claim 5, characterized in that: The guide rods (3), the outer sleeve (2), the inner sleeve (1) and the connecting pieces on the left and right sides of the bracket (4) are respectively arranged in a mirror-like manner.

7. The headrest adjustment structure according to claim 1, characterized in that: The bracket (4) comprises a mounting rod (47) and a locking clip, the guide rod (3) is arranged at the end of the mounting rod (47), the guide rod (3) and the mounting rod (47) are fixedly connected, the locking clip is clamped on the mounting rod (47), and the locking clip is used to install a sofa headrest.

8. The headrest adjustment structure according to claim 7, characterized in that: The bracket (4) further comprises a limit block (7), wherein the limit block (7) is arranged in a U shape, wherein two ends of the U-shaped limit block (7) are respectively fixed on the mounting rod (47), and the locking clamp is arranged between the two ends of the U-shaped limit block (7).

9. The headrest adjustment structure according to claim 7, characterized in that: The locking clamp comprises a first mounting plate and a second mounting plate, the first mounting plate comprising a first front plate (41), a second front plate (42) and a third front plate (43) which are sequentially connected from top to bottom, the second mounting plate comprising a first rear plate (44), a second rear plate (45) and a third rear plate which are sequentially connected from top to bottom, the third front plate (43) being arranged in a C-shape, the second front plate (42) extending vertically, the lower end of the second front plate (42) being fixedly connected to the C-shaped third front plate (43), the first front plate (41) being arranged on the second front plate (42 ), the second front plate (42) abuts against the second rear plate (45) and is fixed by screws, and the first front plate (41) and the first rear plate (44) are arranged at intervals; the first front plate (41), the second front plate (42) and the third front plate (43) are mirror-imaged to the first rear plate (44), the second rear plate (45) and the third rear plate, respectively, one-to-one correspondingly, so that the third front plate (43) and the third rear plate clamp the mounting rod (47), and the first front plate (41) and the first rear plate (44) are used to install the headrest.

10. A sofa, comprising a backrest, characterized in that: It also includes a headrest adjustment structure as described in any one of claims 1 to 9, wherein an opening is provided on the top surface of the backrest, a channel extending in the up-down direction is formed in the opening, the outer sleeve (2) is arranged in the channel, the channel limits the rotation of the outer sleeve (2), the inner sleeve (1) is arranged outside the channel, and a limit frame is provided on the backrest, the limit frame limits the first flange (11) along the axial and radial directions of the inner sleeve (1) to limit the up-and-down movement of the first flange (11).

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