A seat back

Abstract

The utility model relates to a seat manufacturing technical field especially relates to a seat back. The seat back technical scheme provided by the present application is: including chair back frame and waist rest subassembly. The chair back frame contains annular frame body and is used for the support frame that links in the rear end part of seat or tray, and the support frame is integrally connected in the lower end of annular frame body, and the front end face is equipped with flexible support surface layer, and the edge is connected in annular frame body. The waist rest subassembly is connected in chair back frame, and can support the flexible support surface layer forward. The upper end of chair back frame is connected headrest subassembly, and the headrest subassembly contains the base fixed in the upper end of chair back frame, the headrest support that can be slidably arranged in the base and the headrest hinged in the upper end of headrest support. The headrest support is equipped with longitudinal sliding slot and multiple positioning slot holes along the direction of sliding slot;The base contains sliding fit part, and can be slidably arranged in the sliding slot, and the base is equipped with elastic positioning assembly, and when the output end is clamped into the positioning slot hole, the headrest support is positioned relative to the base. The scheme headrest height adjustment is convenient, and positioning is stable and excellent in anti -drop effect.

Description

Technical Field

[0001] This utility model relates to the field of seat manufacturing technology, and in particular to a seat back. Background Technology

[0002] In modern office and home life, people have increasingly higher demands for the comfort and functionality of chairs. Traditional chair backs typically consist of a fixed frame and a simple flexible support surface. To provide better lumbar support, many products have added lumbar support components, which can push forward against the flexible support surface to conform to the curve of the human lumbar spine and improve comfort. However, the headrest configuration of these chair backs is often relatively simple, usually using a fixed structure or only having angle adjustment function. Its height cannot be effectively adjusted according to the user's body shape and sitting posture, or the adjustment mechanism is complicated and inconvenient to operate, making it difficult to meet the personalized needs of different users.

[0003] Specifically, existing adjustable headrest structures have several common problems. Some headrests use a simple pin-and-hole system for height adjustment, which requires two hands and is difficult to align, resulting in a poor user experience. Others use spring-loaded latches, which may be unstable and prone to wobbling or noise due to wear and tear over time. Furthermore, the reliability and ease of assembly of the headrest assembly's connection to the backrest frame, as well as its sliding and locking mechanisms, are key technical issues requiring further optimization. Especially for headrest assemblies requiring frequent height adjustments, current technology often struggles to balance ease of operation and stable positioning, and lacks effective anti-slip mechanisms, thus limiting product lifespan and user experience.

[0004] To address the aforementioned issues, existing technologies urgently need improvement. Summary of the Invention

[0005] In order to solve the above problems, the purpose of this utility model is to provide a seat back with convenient headrest height adjustment, stable positioning and excellent anti-slip effect.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This application provides a chair backrest, the technical solution of which is as follows: it includes a chair back frame and a lumbar support assembly; the chair back frame includes an annular frame and a support frame for connecting to the rear end of the seat or tray, the support frame is integrally connected to the lower end of the annular frame, a flexible support surface layer is provided on the front end surface of the chair back frame, and the edge of the flexible support surface layer is connected to the annular frame; the lumbar support assembly is connected to the chair back frame and can support the flexible support surface layer forward; a headrest assembly is connected to the upper end of the chair back frame, the headrest assembly includes a base fixed to the upper end of the chair back frame, a headrest bracket slidably disposed on the base, and a headrest hinged to the upper end of the headrest bracket; the headrest bracket is provided with a longitudinally arranged sliding groove and a plurality of positioning slots arranged along the direction of the sliding groove; the base includes a sliding mating part, the sliding mating part is slidably disposed in the sliding groove, and an elastic positioning component is provided on the base, when the output end of the elastic positioning component is engaged with the positioning slot, the headrest bracket is positioned relative to the base.

[0008] Furthermore, this application also proposes that the headrest support is constructed in the shape of a "7", including a vertical section and a horizontal section. The vertical section is provided with baffles on both sides, and the space between the two baffles forms a groove, with an opening at the bottom of the groove. The base is provided with sliders on both sides, and the base is pushed into the groove from the opening by the sliders and slides in cooperation with the baffles.

[0009] Furthermore, this application also proposes that the base is provided with a groove, and the elastic positioning component includes a spring and a positioning block disposed in the groove. The spring supports the positioning block, and the positioning end of the positioning block and the positioning slot are fitted with an arc or a bevel. When an external force pushes the headrest bracket longitudinally, the positioning end can be disengaged from or engaged in the positioning slot.

[0010] Furthermore, this application also proposes that the surface of the baffle is provided with a guide groove extending parallel to the slide groove, and a guide block is provided on the bottom surface of the base that contacts the baffle. When the base is pushed into the slide groove, the guide block is located in the guide groove, and the guide block and the lower end of the guide groove form an anti-detachment structure.

[0011] Furthermore, this application also proposes that the lower end of the guide groove is provided with an inlet inclined surface, and the upper end surface of the guide block is set as a mating inclined surface adapted to the inlet inclined surface. When the base is pushed into the slide groove, the mating inclined surface and the inlet inclined surface are interference-fitted and introduced.

[0012] Furthermore, this application also proposes that a first bushing is provided on both sides of the transverse section end of the headrest support, and a second bushing is provided on the rear end of the headrest. The second bushing is inserted between the two first bushings and connected by a rotating shaft.

[0013] Furthermore, this application also proposes that an internal support integrally formed therewith is provided inside the annular frame, and the waist support component is connected to the internal support.

[0014] Furthermore, this application also proposes that the internal support is constructed as a herringbone support, with its three ends all connected to the annular frame, and the lumbar support assembly connected to the central intersection of the herringbone support.

[0015] As can be seen from the above, the seat back and headrest assembly provided in this application achieve headrest height adjustment through the sliding cooperation between the base and the headrest bracket and the elastic positioning component. Combined with the anti-slip guide structure, it ensures convenient operation and stability, and has the characteristics of convenient headrest height adjustment, stable positioning and excellent anti-slip effect. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of a chair back provided for this application.

[0017] Figure 2 This application provides a schematic diagram of the installation of a lumbar support for a chair back.

[0018] Figure 3 This application provides a schematic diagram of the installation of a headrest assembly for a chair back.

[0019] Figure 4 This is a schematic diagram showing the installation of the headrest bracket and the headrest.

[0020] Figure 5 This is a schematic diagram of the headrest support structure.

[0021] Figure 6 This is a schematic diagram of the fixing base structure for the headrest assembly. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more, unless otherwise expressly defined.

[0025] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0026] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] In existing technologies, headrest adjustment mechanisms for chair backs generally suffer from the contradiction of cumbersome operation and unstable positioning. Traditional height adjustment mechanisms often use a pin-and-positioning hole system, requiring users to operate with both hands to insert and remove the pins, and aligning the holes is difficult. Some products use a spring-loaded snap-on structure, which simplifies the operation, but after long-term use, wear and tear can cause positioning failure, resulting in wobbling or abnormal noise. These structural defects make it difficult for users to quickly adjust the headrest position according to different body types, affecting the user experience.

[0028] To address these issues, designers discovered the key lay in developing a self-locking sliding mechanism that retained the flexibility of stepless adjustment while ensuring stable positioning for single-step operation. Analysis of ergonomic data revealed that the headrest height adjustment needed to cover at least three commonly used positions, with the adjustment range controlled within a reasonable limit. Based on this, the design combined a sliding guide structure with an elastic positioning component, utilizing spring force to drive the positioning block and positioning slot to form a self-locking mechanism. Simultaneously, the slide structure was optimized to reduce assembly complexity.

[0029] like Figure 1-6As shown, this application proposes a seat back including a backrest frame 2 and a lumbar support assembly 3. The backrest frame 2 has an annular frame 4 and a connecting support frame 5. The support frame 5 is integrally formed with the lower end of the annular frame 4, and a flexible support surface layer is provided on the front end face. The edge is fixed to the annular frame 4. The lumbar support assembly 3 is connected to the backrest frame 2 and has a forward support function. The upper end of the backrest frame 2 is connected to a headrest assembly 7, which includes a fixed base 8, a sliding headrest bracket 9, and a hinged headrest 10. The headrest bracket 9 is provided with a longitudinal sliding groove 15 and positioning slots 16 distributed along the groove. The base 8 is embedded into the sliding groove 15 through a sliding fit and is equipped with an elastic positioning component to achieve bracket positioning.

[0030] The annular frame 4 refers to a support structure formed by bending metal tubing into a closed ring or by integral injection molding, providing uniform tension distribution for the flexible support surface layer. The support frame 5 is the load-bearing component connecting the seat base and the annular frame 4, which can be formed by welding stamped steel plates or integral injection molding, ensuring overall frame rigidity through integrated design. The flexible support surface layer is an elastic material layer covering the front of the annular frame 4, which can be a mesh structure, with edges fixed to the frame using a hot-pressing edging process. The headrest support 9's groove 15 is a guide channel opened along the length of the support, which can be formed by stamping strips 21 on both sides of the steel plate, with the spacing between the strips 21 forming the groove space. The positioning holes 16 are positioning holes spaced along the length of the groove 15, which can be designed as a rectangular or trapezoidal array, with the hole spacing set to 30-50 mm according to the difference in human sitting posture height. The elastic positioning component refers to a snap-fit ​​mechanism with an automatic reset function. Specifically, it can be a combination of a cylindrical helical spring 25 and a nylon positioning block 26. The preload of the spring 25 is set to 3-5 Newtons to balance the operating force and positioning stability.

[0031] Specifically, when the user applies a longitudinal pushing force to the headrest 10, the headrest bracket 9 moves within the slide groove 15 along the sliding engagement portion of the base 8. The positioning block 26 of the elastic positioning component, under the force of the spring 25, is in a compressed state when not aligned with the positioning slot 16. When the bracket moves to the point where the positioning slot 16 aligns with the positioning block 26, the spring 25 pushes the positioning block 26 into the slot, forming a mechanical interlock, at which point the bracket position is fixed. The hinged headrest 10 allows rotation around the upper axis of the bracket, and the user can adjust the tilt angle of the headrest 10 by applying torque. The sliding engagement between the slide groove 15 and the base 8 adopts a clearance fit design, with the clearance controlled within the range of 0.1-0.3 mm, ensuring smooth sliding while preventing wobbling. Through the above technical solution, this application achieves a one-handed height adjustment function, allowing the user to quickly switch between multiple preset positions simply by pushing the headrest 10. The elastic positioning component maintains a stable engagement when no external force is applied, preventing accidental displacement due to vibration during use. The guide mechanism between the slide 15 and the base 8 ensures that the adjustment process is free of deviation, extending the service life of the mechanism. The headrest 10's angle and height adjustments provide a combined adjustment capability to adapt to the cervical spine curve needs of different users.

[0032] Furthermore, the headrest support 9 is constructed in a "7" shape, including a vertical section 19 and a horizontal section 20. The vertical section 19 has baffles 21 on both sides, and the space between the two baffles 21 forms a groove 15, with a notch 22 at the bottom of the groove 15. The base 8 has sliders 23 on both sides. The base 8 is pushed into the groove 15 through the notch 22 by the sliders 23 and slides in cooperation with the baffles 21. The baffles 21 are protruding structures extending along both sides of the vertical section 19, which can be integrally molded from metal or plastic, and are used to define the lateral boundaries of the groove 15, constraining the sliding trajectory of the sliders 23. The groove 15 is a channel formed by the gap between the two baffles 21, which can be formed by stamping or injection molding. The width of the notch 22 at the bottom is slightly larger than the thickness of the slider 23, facilitating the insertion of the slider 23 into the groove 15 from the bottom. The slider 23 refers to the protruding parts set on both sides of the base 8. Specifically, it can be a metal sheet or plastic part integrally formed with the base 8. Its surface contacts the inner side of the baffle 21 to form a sliding friction pair.

[0033] Specifically, the baffles 21 on both sides of the vertical section 19 form a groove 15 structure with a continuous guide surface. After the sliders 23 on both sides of the base 8 are pushed into the groove 15 along the opening 22, the sliders 23 form surface contact with the inner wall of the baffles 21. When the base 8 moves longitudinally along the groove 15, the baffles 21 mechanically limit the lateral displacement of the sliders 23, preventing the base 8 from shifting laterally during sliding. The width of the opening 22 at the bottom of the groove 15 matches the thickness of the sliders 23, ensuring that the base 8 can only be pushed into the groove 15 in a single direction, preventing misalignment during assembly. The contact surfaces between the baffles 21 and the sliders 23 can be made of a low-friction coefficient material, such as a polytetrafluoroethylene coating, to reduce sliding resistance. Through the above technical solutions, this application realizes the rapid assembly of the headrest assembly 7 and the backrest frame 2, avoiding the structural looseness caused by the assembly of multiple parts; the lateral limiting of the slider 23 by the stop bar 21 enhances the stability during the sliding process and prevents the headrest 10 from shifting laterally during adjustment or use; the single push-in direction design of the slide groove 15 and the slider 23 simplifies the assembly process and reduces the assembly error rate.

[0034] like Figure 3 and 6 As shown, a groove 24 is provided on the base 8. The elastic positioning component includes a spring 25 and a positioning block 26 disposed within the groove 24. The spring 25 supports the positioning block 26. The positioning end 27 of the positioning block 26 and the positioning slot 16 are in an arc-shaped or inclined surface fit. When an external force pushes the headrest bracket 9 longitudinally, the positioning end 27 can exit or engage with the positioning slot 16. The groove 24 refers to the inward recessed space formed by the surface of the base 8, which can be implemented using a rectangular or U-shaped groove structure, used to limit the lateral displacement of the spring 25 and the positioning block 26. The spring 25 is an elastic element with axial compression characteristics, which can be implemented using a helical spring or a wave spring, used to apply a continuous thrust to the positioning block 26. The arc-shaped or inclined surface fit of the positioning end 27 means that the contact surface between the positioning block 26 and the positioning slot 16 is designed as an arc or an inclined plane, which can be implemented using a spherical or wedge-shaped structure, guiding the contact and separation action of the positioning block 26 and the positioning slot 16 through the geometric surface. Specifically, when the headrest support 9 is pushed longitudinally, the sidewall of the positioning slot 16 and the arc or slope of the positioning end 27 interact, forcing the positioning block 26 to retract into the groove 24 against the pressure of the spring 25, thereby disengaging the positioning end 27 from the current positioning slot 16. When the external force disappears, the spring 25 pushes the positioning block 26 back to its original position, causing the positioning end 27 to automatically engage with the adjacent positioning slot 16 to complete the height adjustment. During this process, the groove 24 constrains the movement trajectory of the positioning block 26, preventing jamming caused by skewness, while the arc or slope reduces the frictional resistance of the contact surface, allowing the adjustment operation to be completed with only one hand.

[0035] In addition, such as Figure 5As shown, the surface of the stop bar 21 is provided with a guide groove 28 extending parallel to the slide groove 15. A guide block 29 is provided on the bottom surface of the base 8 that contacts the stop bar 21. When the base 8 is pushed into the slide groove 15, the guide block 29 is positioned within the guide groove 28, and the guide block 29 and the lower end of the guide groove 28 form an anti-detachment structure. The guide groove 28 refers to a linear groove formed on the surface of the stop bar 21 along the direction of the slide groove 15. It can be achieved through machining or injection molding and is used to limit the lateral displacement of the base 8 during sliding. The guide block 29 refers to a protruding structure on the bottom surface of the base 8. It can be made of metal or plastic integrally formed with the base 8 and is used to embed within the guide groove 28 to provide sliding trajectory constraint. The anti-detachment structure refers to the guide groove...

[0036] The mechanical limiting structure between the lower end of the base 8 and the guide block 29 can be implemented using a beveled fit or a snap-fit ​​structure to prevent the base 8 from accidentally detaching from the slide groove 15. Specifically, after the base 8 is pushed into the slide groove 15 from the slot 22 by the slider 23, the guide block 29 is restricted to slide linearly within the guide groove 28, avoiding misalignment due to lateral displacement. The linear fit between the guide groove 28 and the guide block 29 ensures precise and controllable sliding trajectory of the base 8 and the headrest support 9. When the base 8 slides to the end of the slide groove 15, the guide block 29 and the beveled surface or snap-fit ​​at the lower end of the guide groove 28 form an interference fit, creating mechanical interference to prevent the base 8 from detaching from the slide groove 15 due to external force. Through the above technical solution, this application solves the assembly difficulties or sliding detachment problems caused by structural instability during the sliding fit between the base 8 and the headrest support 9, realizes precise guidance of the sliding trajectory and reliable limiting of the anti-detachment structure, and improves the overall stability and service life of the headrest assembly 7.

[0037] Furthermore, the lower end of the guide groove 28 is provided with an inlet ramp 30, and the upper end surface of the guide block 29 is provided with a mating ramp 31 adapted to the inlet ramp 30. When the base 8 is pushed into the slide groove 15, the mating ramp 31 and the inlet ramp 30 are interference-fitted and guided in. The inlet ramp 30 refers to the inclined surface provided at the lower end of the guide groove 28 to guide the base 8 into the slide. Specifically, it can be formed by machining or injection molding, and its inclination angle can be, for example, 30° to 60°. This ramp reduces the initial contact resistance between the guide block 29 and the guide groove 28, making it easier for the base 8 to slide into the slide groove 15. The mating ramp 31 refers to the inclined surface provided on the upper end surface of the guide block 29 that matches the inlet ramp 30. Specifically, it can be achieved by milling or molding, and its inclination angle is consistent with the inlet ramp 30. This ramp forms a gradual contact with the inlet ramp 30 during assembly, avoiding structural deformation caused by hard collisions. In this context, the interference fit refers to the slight compression formed when the mating inclined surface 31 and the guiding inclined surface 30 come into contact. Specifically, this can be achieved by controlling the dimensional tolerances of the inclined surfaces to induce elastic deformation at the contact surfaces. This fit method increases frictional resistance to prevent the base 8 from accidentally disengaging during sliding.

[0038] Specifically, when the base 8 is pushed into the slide groove 15, the mating inclined surface 31 at the upper end of the guide block 29 first contacts the guide inclined surface 30 at the lower end of the guide groove 28. Due to the matching angles between the inclined surfaces, when the base 8 is pushed, the mating inclined surface 31 gradually slides into the guide groove 28 along the guide inclined surface 30. The elastic deformation generated by the interference fit makes the guide block 29 and the guide groove 28 form a tight contact, while the frictional resistance limits the displacement of the base 8 under non-human operation. This process does not require precise manual alignment, reducing the assembly difficulty, and the inclined surface contact avoids component damage caused by rigid collision. Through the above technical solution, this application realizes the rapid assembly of the base 8 and the slide groove 15, reduces manual operation time and the risk of component damage, and at the same time enhances the stability of the sliding structure through the interference fit, preventing accidental disengagement due to vibration or external force during use.

[0039] like Figure 4As shown, first bushings 13 are provided on both sides of the end of the transverse section 20 of the headrest support 9, and a second bushing 14 is provided on the rear end of the headrest 10. The second bushing 14 is inserted between the two first bushings 13 and connected by a rotating shaft. The first bushing 13 refers to the cylindrical sleeve structure provided on both sides of the end of the transverse section 20 of the headrest support 9. Specifically, it can be integrally formed with the support using injection molding, and its inner diameter matches the outer diameter of the rotating shaft to provide rotational support. The second bushing 14 refers to the cylindrical sleeve structure provided at the rear end of the headrest 10. Specifically, it can be injection molded as a split metal sleeve insert, and its outer diameter is clearance-fitted with the inner diameter of the first bushing 13 to achieve nested assembly with the first bushing 13. The rotating shaft connection refers to the metal rod passing through the first bushing 13 and the second bushing 14. Specifically, it can be a pin structure with an anti-disengagement spring, achieving synchronous rotation of the three through axial fixation. Specifically, the first bushings 13 on both sides of the end of the transverse segment 20 of the headrest bracket 9 form two symmetrically distributed support points, and the second bushing 14 at the rear end of the headrest 10 is embedded between them to form a three-point contact. When the rotating shaft passes through the first bushing 13, the second bushing 14, and then through the first bushing 13 on the other side in sequence, the coaxiality of the three is automatically corrected by the nested structure. During the rotation of the headrest 10, the contact surfaces of the first bushing 13 and the second bushing 14 form a surface contact friction pair, which can increase the contact area by more than twice compared with the single-point hinge structure. At the same time, the first bushings 13 on both sides form an axial limit on the second bushing 14, preventing the rotating bearing from being subjected to lateral shear force. During the assembly process, it is only necessary to align the second bushing 14 with the gap between the first bushings 13 on both sides and insert it, and then insert the rotating shaft to complete the hinge, without the need for additional positioning fixtures. Through the above technical solution, this application solves the problem of low assembly efficiency caused by the complex connection structure between the headrest 10 and the bracket, and avoids the defect of abnormal noise caused by easy wear of the bushing on one side. The nested bushing structure disperses stress through surface contact, extending the service life of the hinged parts. At the same time, it simplifies the assembly process, requiring only a single shaft to achieve a reliable connection, thus reducing production costs.

[0040] like Figure 1 and 2 As shown, the annular frame 4 has an integrally formed internal support 11, and the lumbar support assembly 3 is connected to the internal support 11. The integrally formed internal support 11 refers to the support structure formed with the annular frame 4 using the same mold or molding process, specifically injection molding or metal casting. Its function is to eliminate the assembly gap at the connection between the separate support and the frame, enhancing the overall structural rigidity. The lumbar support assembly 3 being connected to the internal support 11 means that the installation position of the lumbar support is transferred from the frame surface to a specific area of ​​the internal support 11. This can be achieved by bolt fixing or snap-fitting. Its function is to form a multi-level force transmission path through the rigid support of the internal support 11, preventing the flexible support surface from directly bearing the support force.

[0041] Specifically, the internal support 11 and the annular frame 4 are integrally formed to create a continuous load-bearing structure. When the lumbar support component 3 applies a supporting force, the load is evenly transmitted to multiple connection points of the annular frame 4 through the internal support 11, dispersing local stress concentration. Simultaneously, the rigid support of the internal support 11 avoids the risk of deformation or tearing of the flexible support surface layer due to direct stress in traditional solutions. For example, when the internal support 11 has a herringbone structure, a triangular support effect is formed at its central intersection, further optimizing the load distribution path. Through the above technical solution, this application solves the problem of dispersed support force caused by unstable connection between the lumbar support component 3 and the chair back frame 2, achieving uniform transmission of lumbar support force, improving the stability of lumbar support movements, and extending the service life of the flexible support surface layer.

[0042] In a further embodiment, the internal support 11 is constructed as a herringbone structure, with all three ends connected to the annular frame 4. The lumbar support assembly 3 is connected to the central intersection of the herringbone structure. The herringbone structure refers to a support structure with three connection points formed by two intersecting members. It can be made of metal tubing or reinforced plastic through welding or injection molding. The three ends are fixedly connected to the annular frame 4 to form a stable triangular support. The central intersection refers to the area where the two intersecting members meet. The lumbar support assembly 3 can be installed at this location through welding, riveting, or bolting, allowing the support force to be distributed and transmitted along the intersecting members.

[0043] Specifically, the two members of the A-frame are arranged at a certain angle, with the three ends fixed to the sides and bottom of the annular frame 4, forming a triangular geometric support. When the lumbar support component 3 applies a supporting force through the connection point at the central intersection, the force is transmitted to the three fixed ends through the two intersecting members, avoiding stress concentration at a single connection point. The included angle of the intersecting members can be adjusted according to the size of the annular frame 4, for example, within the range of 60° to 120°, to ensure that the support remains rigid when bearing the lumbar support force. Reinforcing ribs or flared structures can be provided at the connection between the annular frame 4 and the A-frame to further prevent deformation of the connection point due to long-term stress. Through the above technical solution, this application solves the problem of insufficient strength caused by single-point connection in traditional supports, improves the overall rigidity through the triangular support structure, and evenly distributes the supporting force of the lumbar support component 3 to the annular frame 4, ensuring that the flexible support surface layer maintains uniform deformation under stress and avoiding local collapse. The symmetrical arrangement of the cross members simplifies the installation and positioning of the lumbar support assembly 3, and stable support can be achieved through a single connection point at the central intersection.

[0044] In summary, the seat back and its headrest assembly 7 provided in this application achieve headrest height adjustment through the sliding cooperation between the base 8 and the headrest bracket 9 and the elastic positioning assembly. Combined with the anti-slip guide structure, it ensures convenient operation and stability, and has the characteristics of convenient headrest height adjustment, stable positioning and excellent anti-slip effect.

[0045] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A chair back, comprising a chair back frame (2) and a lumbar support assembly (3); the chair back frame (2) comprises an annular frame (4) and a support frame (5) for connecting to the rear end of a seat or tray, the support frame (5) being integrally connected to the lower end of the annular frame (4), a flexible support surface layer being provided on the front end surface of the chair back frame (2), the edge of the flexible support surface layer being connected to the annular frame (4); the lumbar support assembly (3) being connected to the chair back frame (2), the lumbar support assembly (3) being able to support the flexible support surface layer forward; Its features are: The upper end of the chair back frame (2) is connected to a headrest assembly (7). The headrest assembly (7) includes a base (8) fixed to the upper end of the chair back frame (2), a headrest bracket (9) slidably disposed on the base (8), and a headrest (10) hinged to the upper end of the headrest bracket (9). The headrest bracket (9) is provided with a longitudinally arranged sliding groove (15) and a plurality of positioning slots (16) arranged along the direction of the sliding groove (15); The base (8) is slidably disposed in the slide groove (15), and the base (8) is provided with an elastic positioning component for engaging with the positioning slot (16); When the output end of the elastic positioning component is inserted into the positioning slot (16), the headrest bracket (9) is positioned relative to the base (8).

2. A seat back as described in claim 1, characterized in that: The headrest support (9) is constructed in the shape of a "7". The headrest support (9) has baffles (21) on both sides of the vertical section (19), and the vertical section (19) between the two baffles (21) forms the groove (15), and the groove (15) extends to the bottom to form a slot (22); the base (8) has sliders (23) on both sides, and the base (8) is pushed into the groove (15) from the slot (22), and the sliders (23) on both sides of the base (8) are pushed into the groove (15) and cooperate with the baffles (21).

3. A seat back as described in claim 1, characterized in that: The base (8) is provided with a groove (24). The elastic positioning component includes a spring (25) and a positioning block (26) disposed in the groove (24). The spring (25) is supported on the positioning block (26). The positioning slot (16) and the positioning end (27) of the positioning block (26) are arc-shaped or inclined, so that when the external force pushes the headrest bracket (9) longitudinally, the positioning end (27) can be withdrawn from or inserted into the positioning slot (16).

4. A seat back as described in claim 2, characterized in that: The surface of the baffle (21) is provided with a guide groove (28) that is parallel to the slide groove (15). A guide block (29) is provided on the bottom surface of the base (8) that is in contact with the baffle (21). When the base (8) is pushed into the slide groove (15), the guide block (29) is in the guide groove (28). The guide block (29) and the lower end of the guide groove (28) form an anti-detachment structure.

5. A seat back according to claim 4, characterized in that: The lower end of the guide groove (28) is provided with an inlet inclined surface (30), and the upper end surface of the guide block (29) is provided with a mating inclined surface (31) that is adapted to the inlet inclined surface (30). So that during the process of pushing the base (8) into the groove (15), the inclined surface (31) and the guide inclined surface (30) are interference-fitted.

6. A seat back as described in claim 2, characterized in that: The headrest bracket (9) has a first bushing (13) on both sides of the transverse section (20) end, and a second bushing (14) is provided on the rear end of the headrest (10) and is inserted between the two first bushings (13). The second bushing (14) is connected to the two first bushings (13) on both sides by a rotating shaft.

7. A seat back as described in claim 1, characterized in that: The annular frame (4) is provided with an internal support (11) integrally formed therewith, and the waist support component (3) is connected to the internal support (11).

8. A seat back according to claim 7, characterized in that: The internal support (11) is constructed as a herringbone support, with its three ends connected to the annular frame (4); the lumbar support assembly (3) is connected at the central intersection of the herringbone support.

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