Headrest and office chair

Abstract

The utility model relates to a headrest and office chair, including the clamping component and headrest subassembly for fixed installation on the back of a chair, the clamping component includes the front casing and rear casing that connect with each other, the front casing and rear casing form the vertical guide channel between, the front casing side to the guide channel is provided with a plurality of second positioning recesses along the vertical interval, the headrest subassembly includes the elevating support and headrest body, the elevating support is connected with the headrest body rotation through the pivot, the elevating support is set outside the clamping component, the inner chamber middle part of elevating support is fixed with the positioning core plate, the positioning core plate is inserted in the guide channel and can slide along the guide channel up and down, be provided with the elastic positioning piece on the positioning core plate, the elastic positioning piece is under the action of the elasticity and is in butt and is connected in the second positioning recess, to realize the elevating adjustment and positioning of headrest subassembly relative to the clamping component.

Description

Technical Field

[0001] This utility model relates to headrests and office chairs. Background Technology

[0002] Existing office chair headrests typically use a fixed connection to the chair back, with a relatively constant installation height that cannot be adjusted. However, due to significant differences in the height, body type, and sitting posture of different users, this fixed-height headrest often fails to accurately match the user's neck position. As a result, when the user leans back, the headrest cannot provide effective support and fit to the cervical spine, causing the neck to be in a suspended or unevenly stressed state for a long time. This can easily lead to fatigue symptoms such as neck pain and muscle stiffness, and fails to meet the needs of modern office chairs for ergonomic comfort and personalized customization. Utility Model Content

[0003] The primary objective of this invention is to provide a height-adjustable headrest.

[0004] The second objective of this invention is to provide an office chair with an adjustable headrest.

[0005] The primary objective of this invention is achieved as follows: A headrest includes a clamping assembly for fixing it to a chair back and a headrest assembly. The clamping assembly includes a front housing and a rear housing connected to each other. The front housing and the rear housing enclose a vertical guide channel. The front housing has a plurality of second positioning grooves spaced vertically on the side facing the guide channel. The headrest assembly includes a lifting bracket and a headrest body. The lifting bracket is rotatably connected to the headrest body via a rotating shaft. The lifting bracket is sleeved on the outside of the clamping assembly. A positioning core plate is fixedly provided in the middle of the inner cavity of the lifting bracket. The positioning core plate passes through the guide channel and can slide up and down along the guide channel. The positioning core plate is provided with an elastic positioning element. Under the action of elastic force, the elastic positioning element abuts against and engages in the second positioning groove to realize the lifting adjustment and positioning of the headrest assembly relative to the clamping assembly.

[0006] The headrest adopts a three-layer nested structure, in which the lifting bracket is sleeved on the outside of the clamping component and the positioning core plate is inserted into the internal guide channel. This is combined with the engagement of the elastic positioning component and the second positioning groove. This achieves flexible adjustment and stable locking of the headrest height, solving the problem that the fixed headrest height in the existing technology cannot match users of different heights.

[0007] The primary objective of this utility model can also be achieved by the following technical measures: Furthermore, the clamping assembly also includes a lower pressure plate connected to the bottom of the rear housing. The front end of the lower pressure plate extends forward to form a lower clamping portion, and the top of the front housing extends forward to form an upper clamping portion. The upper clamping portion and the lower clamping portion cooperate to form a C-shaped clamping space for clamping the chair back.

[0008] A stable C-shaped clamping space is created through the mating structure formed by the lower pressure plate and the top extension of the front shell. This allows for quick installation and removal of the headrest without drilling holes in the chair back or using complex screw connections, solving the technical problems of poor installation versatility and easy damage to the chair back structure of existing headrests. This clamping method distributes force evenly and can fit tightly against the edge of the chair back, ensuring that the headrest will not loosen or fall off during use.

[0009] Furthermore, the top of the lifting bracket is provided with a rotating groove, and the headrest body includes a connecting seat and a headrest frame. The lower part of the connecting seat is rotatably installed in the rotating groove through a damping shaft. The front end of the connecting seat is fixedly connected to the headrest frame, and the rear end of the connecting seat extends to form a limiting baffle. When the headrest body rotates to the limit angle, the limiting baffle abuts against the top surface of the lifting bracket to limit the rotation angle of the headrest body.

[0010] The headrest is connected to the bracket by a damping pivot, and a limiting baffle extending from the rear end of the connecting seat is set to cooperate with the top surface of the bracket. This not only realizes stepless adjustment and suspension of the headrest angle, improving the fit, but also uses the limiting baffle to form a physical stop structure, solving the technical problem that excessive rotation angle of existing headrests can easily lead to neck sprains or damage to the internal hinge structure, thus balancing the comfort of adjustment and the service life of the product.

[0011] Furthermore, the elastic positioning element is an elastic sheet, and the surface of the positioning core plate is provided with an installation groove. The elastic sheet is fixedly installed in the installation groove. The elastic sheet has a positioning protrusion on one side facing the front housing. The positioning protrusion pushes outward and is inserted into the second positioning groove under the elastic force of the elastic sheet itself.

[0012] The spring itself is used to drive the positioning protrusion to engage with the groove; thus, while ensuring clear positioning and crisp adjustment, the number of parts and assembly difficulty are greatly reduced.

[0013] Furthermore, the side wall of the guide channel is provided with a vertical guide groove, and the positioning core plate is provided with a guide slider corresponding to the position of the guide groove. The guide slider slides in the guide groove to limit the left and right swaying of the lifting bracket.

[0014] A vertical guide groove and guide slider are added to provide a second layer of limiting constraint for the lifting movement. This effectively eliminates the assembly gap between the positioning core plate and the housing, and solves the technical problem that existing lifting headrests are prone to swaying left and right (large play) when stretched to the high position, which affects the user experience. This ensures the smoothness and tightness of the lifting adjustment throughout the entire process.

[0015] Furthermore, the headrest frame is an arc-shaped frame, and an elastic mesh is stretched on the arc-shaped frame, forming a breathable headrest support surface between the elastic mesh and the arc-shaped frame.

[0016] The structure uses an arc-shaped frame with elastic mesh fabric, which provides a cool and comfortable support surface for the user's neck by utilizing the high breathability and flexible deformation of the mesh fabric. This solves the technical problems of traditional sponge head pillows, such as heat accumulation, sweating, bacterial growth, and strong pressure, which are common when leaning on them for a long time. This improves the comfort of working for long periods of time.

[0017] The second objective of this utility model is achieved as follows: An office chair includes a backrest, a seat cushion, a base assembly, armrests, and a headrest. The seat cushion is disposed on the base assembly, the backrest is connected to the seat cushion, the headrest is installed on the top of the backrest, and the armrests are respectively installed on both sides of the seat cushion. The base assembly is provided with a backrest tilt adjustment mechanism and an electric lifting drive device.

[0018] By integrating the aforementioned multi-functional adjustable headrest, combined with the electric height and tilt adjustment functions of the base, the office chair constructs a comprehensive ergonomic support system. This ensures that whether the user is sitting upright at work or reclining for a nap, their neck, back, and buttocks receive precise and adaptive support. It solves the technical problem of traditional office chairs having limited functions and failing to meet the health needs of prolonged desk work, greatly improving the product's comfort and user experience.

[0019] The beneficial effects of this utility model are as follows: This invention enables flexible adjustment and precise positioning of the headrest height, effectively avoiding the problems of traditional exposed structures that easily pinch fingers and create a cluttered appearance. Simultaneously, the dual constraint design of the main guide channel and auxiliary guide groove effectively eliminates left-right swaying and assembly misalignment during the lifting process, ensuring smooth adjustment and overall structural rigidity.

[0020] This invention, through its innovative C-shaped clamping space design, enables quick installation and disassembly without drilling holes in the chair back or using complex tools, thus improving the product's versatility. Furthermore, the damping hinge of the headrest, combined with a physical limit baffle design, allows for stepless angle adjustment to conform to the neck curve while providing reliable protection against excessive rotation, preventing internal mechanism breakage or neck sprains, thus balancing durability and safety.

[0021] This invention, with its arc-shaped frame and breathable support surface made of elastic mesh fabric, effectively solves the problem of heat accumulation and sweating caused by prolonged use of traditional sponge headrests. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the chair back.

[0023] Figure 2 This is the assembly drawing for the chair back.

[0024] Figure 3 This is an assembly drawing of the support frame and the limiting sleeve.

[0025] Figure 4 This is an assembly drawing of the lumbar support plate and support frame.

[0026] Figure 5 This is an assembly drawing of the lumbar support plate and support frame from another angle.

[0027] Figure 6 This is a diagram of an office chair.

[0028] Figure 7 This is a diagram of an office chair (headrest raised).

[0029] Figure 8 This is a schematic diagram of a handrail.

[0030] Figure 9 This is a schematic diagram of the handrail from another angle.

[0031] Figure 10 This is an assembly drawing of the sliding cover and the base.

[0032] Figure 11 This is an assembly drawing of the sliding cover, the limiting guide block, and the base.

[0033] Figure 12 This is an assembly drawing of the sliding cover, limiting guide block, bottom shell, and cover plate.

[0034] Figure 13 This is an exploded view of the handrail.

[0035] Figure 14 This is a schematic diagram of the armrest (with the sliding cover moved back).

[0036] Figure 15This is a schematic diagram of a headrest.

[0037] Figure 16 This is a cross-sectional view of the headrest.

[0038] Figure 17 This is an assembly diagram of the headrest.

[0039] Figure 18 This is an assembly drawing of the clamping components.

[0040] Figure 19 This is an assembly diagram of the clamping assembly from another angle.

[0041] Figure 20 This is the left view of the office chair.

[0042] Figure 21 This is a left view of the office chair (headrest rotated). Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments: Implementation examples, in conjunction with Figures 1 to 21 As shown, an office chair includes a backrest 1, a seat cushion 10, a base assembly 20, armrests 2, and a headrest 3. The seat cushion 10 is mounted on the base assembly 20, the backrest 1 is connected to the seat cushion 10, the headrest 3 is mounted on the top of the backrest 1, and the armrests 2 are respectively mounted on both sides of the seat cushion 10. The base assembly 20 is provided with a backrest tilt adjustment mechanism and an electric lifting drive device for raising and lowering the seat cushion 10.

[0044] The chair back tilt adjustment mechanism is used to adjust the tilt angle of the chair back 1 relative to the seat cushion 10; the electric lifting drive device is used to adjust the height of the seat cushion 10. The chair back tilt adjustment mechanism and the electric lifting drive device can be implemented using common structures in the art, and this embodiment does not limit their specific structural form, as long as they can achieve the corresponding functions. To facilitate tilt adjustment, the chair back 1 and the seat cushion 10 can be rotatably connected.

[0045] To facilitate the tilt adjustment of the chair back 1 and the height adjustment of the seat cushion 10, this embodiment includes a control and transmission structure inside the armrest 2, allowing the user to perform the corresponding operations while seated.

[0046] In one embodiment, the chair back 1 includes a chair back frame 11, a lumbar support assembly 12, and a first elastic member 13. The chair back frame 11 is provided with a mounting cavity 111, and a mounting post 112 is fixedly disposed in the mounting cavity 111.

[0047] The lumbar support assembly 12 includes a lumbar support plate 121, a support frame 122, and a limiting sleeve 123. The lumbar support plate 121 is rotatably connected to the head of the support frame 122. The support frame 122 has a sliding channel 124 along its length, and a first limiting part 125 is provided on the inner wall of the sliding channel 124 near one end. The limiting sleeve 123 has a hollow structure, and a second limiting part 126 is provided at its top end. The second limiting part 126 is used to cooperate with the first limiting part 125 to achieve stroke limitation.

[0048] During assembly, the tail of the support frame 122 extends into the mounting cavity 111; the limiting sleeve 123 passes through the sliding channel 124 and is sleeved and fixed on the mounting post 112, allowing the support frame 122 to slide axially relative to the limiting sleeve 123. The first elastic element 13 is sleeved on the limiting sleeve 123, with one end of the first elastic element 13 abutting against the inner wall of the mounting cavity 111 and the other end abutting against the support frame 122, thereby causing the first elastic element 13 to exert an outward pushing force on the support frame 122 until the second limiting part 126 and the first limiting part 125 abut against each other, so as to realize the outward extension and stroke limitation of the lumbar support assembly 12.

[0049] To limit the movement path of the lumbar support assembly 12 and improve sliding stability, guide holes 1221 are opened at intervals along the length direction on the support frame 122, and guide posts 1111 are set at corresponding intervals in the mounting cavity 111. The guide posts 1111 are inserted into the guide holes 1221, thereby guiding the movement direction of the lumbar support assembly 12 and limiting the sway.

[0050] To achieve a rotatable connection between the lumbar support plate 121 and the support frame 122, a connecting cavity 1222 is provided on the back of the lumbar support plate 121. The size of the connecting cavity 1222 is larger than the size of the head of the support frame 122. During assembly, the head of the support frame 122 is inserted into the connecting cavity 1222, and the pivot passes through the connecting cavity 1222 and the head of the support frame 122, thus forming a rotatable connection between the lumbar support plate 121 and the support frame 122. The inner wall of the connecting cavity 1222 is used to limit the rotation angle of the lumbar support plate 121 to avoid excessive rotation that could lead to instability in the support or structural interference.

[0051] To ensure that the lumbar support 121 maintains an outward tilted support posture towards the seating space under no external force or light load conditions, at least two second elastic members 1223 are provided at the top of the head of the support frame 122, and the lumbar support 121 has an abutment portion 1211 at the corresponding position. Under the action of its elastic force, the second elastic members 1223 continuously push against the abutment portion 1211 until the head of the support frame 122 abuts against the inner wall of the connecting cavity 1222, thereby keeping the lumbar support 121 in an outward tilted state and improving the fit and support effect.

[0052] The lumbar support 121 can be a flexible curved panel, which is concave to the side of the user; the two sides of the lumbar support 121 extend forward to form a wrap-around part, which is used to provide wrap-around support for the human waist to improve lateral support and comfort.

[0053] In terms of the working process: when the user applies force to the lumbar support plate 121, the lumbar support plate 121 can rotate adaptively relative to the support frame 122 at the pivot point; at the same time, the support frame 122 can generate a certain stroke of axial elastic displacement under the action of the first elastic element 13, and rebound to its original position after the external force decreases, thereby achieving adaptive support for different body shapes and sitting postures.

[0054] In one embodiment, the armrest 2 includes a support arm 21 and a hand support assembly 4. The hand support assembly 4 includes a base 41 and a sliding cover 42. The base 41 is fixedly mounted on the top end of the support arm 21; the sliding cover 42 has a groove 421 along its length, and a limiting guide block 5 is provided in the groove 421. The limiting guide block 5 passes through the groove 421 and is fixedly connected to the base 41, thereby allowing the sliding cover 42 to slide and adjust relative to the base 41 along its length. The limiting guide block 5 is used to limit the sliding stroke of the sliding cover 42, where the length direction is along the front-back direction of the armrest 2 (i.e., the sliding direction of the sliding cover 42).

[0055] To achieve sliding positioning, the side wall of the limiting guide block 5 is provided with an elastic protrusion 51, and the inner wall of the slide groove 421 is provided with a plurality of first positioning grooves 52 at intervals along the length direction. During the sliding process of the sliding cover 42, the elastic protrusion 51 can selectively engage or disengage between the first positioning grooves 52 to achieve segmented positioning and tactile feedback.

[0056] To improve assembly reliability, a first opening 422 is provided at the bottom of the slide groove 421. The length of the first opening 422 is the same as the length of the slide groove 421, but its width is less than the width of the slide groove 421, thus forming a stepped surface 423 within the slide groove 421. The width of the limiting guide block 5 is greater than the width of the first opening 422 and abuts against the stepped surface 423. A connecting post 413 is provided on the base 41. The connecting post 413 passes through the first opening 422 and is locked and fixed to the limiting guide block 5, thereby achieving a reliable connection between the limiting guide block 5 and the base 41 and ensuring the stable sliding of the sliding cover 42.

[0057] To improve guiding accuracy, guide ribs are provided along the length direction on the side walls of the slide groove 421 on both sides of the first opening 422, and guide grooves are provided at the corresponding positions of the limiting guide block 5. The guide ribs slide and fit in the guide grooves to suppress the left and right shaking of the sliding cover 42.

[0058] The base 41 may include a bottom shell 411 and a cover plate 412. The cover plate 412 covers and is fixed on the bottom shell 411, and the cover plate 412 and the bottom shell 411 enclose a receiving cavity. The connecting column 413 may be integrally formed on the cover plate 412 to reduce the number of parts and improve assembly consistency.

[0059] To enable the tilt adjustment of the chair back 1, the handrest assembly 4 also includes a paddle 43 and a control cable. A paddle mounting port 431 is provided on the side wall of the bottom shell 411, and the paddle 43 is rotatably mounted at the paddle mounting port 431 via a pivot. A cable passage hole 432 is provided at the bottom of the bottom shell 411. The support arm 21 has a hollow structure, with a cable outlet hole 433 at its lower end. One end of the control cable is connected to the paddle 43, and the other end passes sequentially through the cable passage hole 432, the hollow cavity of the support arm 21, and the cable outlet hole 433, and is connected to the locking and releasing component of the chair back tilt adjustment mechanism or its control end. When the paddle 43 rotates, it drives the control cable to pull or return, thereby driving the chair back tilt adjustment mechanism to unlock or lock, thus achieving the tilt adjustment of the chair back 1.

[0060] To enable seat cushion lifting control, a button hole 211 is provided on the side wall of the support arm 21. A micro switch is built into the support arm 21, and a button 212 is movably set in the button hole 211 and used to trigger the micro switch. One end of the wire is connected to the micro switch, and the other end passes through the wire outlet hole 433 of the support arm 21 and is electrically connected to the control module of the electric lifting drive device to realize seat cushion lifting operation.

[0061] To enhance tactile feel and comfort, a polyurethane pad 44 can be fixedly mounted on the top of the sliding cover 42, covering the upper surface of the sliding cover 42.

[0062] In other embodiments, the elastic protrusion 51 may adopt a "compression spring and positioning ball" structure: a blind hole is formed on the side wall of the limiting guide block 5, the compression spring is housed in the blind hole, and the positioning ball is located at the end of the compression spring away from the bottom of the blind hole; the compression spring is in a compressed state and pushes against the positioning ball outward, so that a portion of the spherical surface of the positioning ball protrudes from the opening of the blind hole. The first positioning groove 52 is set as an arc-shaped groove that matches the curvature of the spherical surface of the positioning ball to improve positioning stability and reduce wear.

[0063] In one embodiment, the headrest 3 includes a clamping assembly 6 and a headrest assembly 7. The clamping assembly 6 is used to fix it to the backrest 1, and the headrest assembly 7 is used to realize height adjustment and angle adjustment.

[0064] The clamping assembly 6 includes a front housing 61 and a rear housing 62 connected to each other, and the front housing 61 and the rear housing 62 enclose each other to form a vertical guide channel 63; a plurality of second positioning grooves 611 are provided vertically at intervals on the side of the front housing 61 facing the guide channel 63.

[0065] The headrest assembly 7 includes a lifting bracket 71 and a headrest body 72. The lifting bracket 71 is sleeved on the outside of the clamping assembly 6, and a positioning core plate 73 is fixedly installed in the middle of the inner cavity of the lifting bracket 71. The positioning core plate 73 is inserted into the guide channel 63 and can slide up and down along the guide channel 63, thereby realizing the height adjustment of the headrest 3. The headrest body 72 is rotatably connected to the lifting bracket 71 through a rotating shaft to realize the headrest angle adjustment.

[0066] To achieve height-level positioning, an elastic positioning element 731 is provided on the positioning core plate 73. The elastic end of the elastic positioning element 731 is used to abut against and engage with the second positioning groove 611, thereby realizing the lifting adjustment and level positioning of the headrest assembly 7 relative to the clamping assembly 6.

[0067] The clamping assembly 6 may also include a lower pressure plate 64, which is connected to the bottom of the rear housing 62 and extends forward to form a lower clamping part 641; the top of the front housing 61 extends forward to form an upper clamping part 612, and the upper clamping part 612 and the lower clamping part 641 cooperate to form a C-shaped clamping space 613 for clamping the chair back 1.

[0068] In other embodiments, the upper clamping part 612 and the lower clamping part 641 can clamp and fix the chair back 1 by means of screw locking, snap-fit ​​engagement or elastic clamping, so that the headrest 3 can be quickly assembled on the top area of ​​the chair back 1.

[0069] To limit the rotation range of the headrest body 72, a rotation groove is provided on the top of the lifting bracket 71. The headrest body 72 may include a connecting seat 8 and a headrest frame 9. The lower part of the connecting seat 8 is rotatably mounted in the rotation groove via a damping shaft. The front end of the connecting seat 8 is fixedly connected to the headrest frame 9, and the rear end of the connecting seat 8 extends to form a limiting baffle 81. When the headrest body 72 rotates to its limit angle, the limiting baffle 81 abuts against the top surface of the lifting bracket 71 to limit the rotation angle of the headrest body 72 and improve safety during use.

[0070] In other embodiments, the elastic positioning member 731 may adopt an elastic spring sheet structure: an installation groove is opened on the surface of the positioning core plate 73, and the elastic spring sheet is fixedly installed in the installation groove; the elastic spring sheet protrudes a positioning protrusion on the side facing the front housing 61, and the positioning protrusion pushes outward and is inserted into the second positioning groove 611 under the elastic force of the elastic spring sheet itself, so as to achieve height positioning and anti-retraction.

[0071] To limit left and right swaying during the lifting process, the side wall of the guide channel 63 is provided with a vertical guide groove, and the positioning core plate 73 is provided with a guide slider at the corresponding position. The guide slider slides in the guide groove, thereby improving the lifting stability of the headrest 3.

[0072] The headrest 9 can be an arc-shaped frame with an elastic mesh fabric stretched on it. The elastic mesh fabric and the arc-shaped frame form a breathable headrest support surface to improve heat dissipation and comfort.

[0073] The user places the office chair on a level surface and sits on the seat cushion 10, then adjusts and uses it as follows: Seat height adjustment: The user presses the button located on the side wall of the support arm 21. The button triggers the micro switch inside the support arm 21. The micro switch sends a control signal to the control module of the electric lifting drive device via a wire, thereby driving the electric lifting drive device to move and raise or lower the seat 10. When the seat height reaches the desired position, the button is released to stop the adjustment.

[0074] Backrest 1 tilt angle adjustment: The user moves the lever 43 on the handrest assembly 4. The lever 43 rotates and drives the control cable to pull or return, thereby driving the locking and releasing component of the backrest tilt adjustment mechanism to unlock or lock. In the unlocked state, the user applies force with their back to rotate the backrest 1 relative to the seat cushion 10 to the target tilt angle, and then resets the lever 43 to lock the backrest tilt adjustment mechanism, thereby realizing the adjustment and maintenance of the backrest 1 tilt angle.

[0075] The lumbar support assembly 12 provides adaptive support: When the user's back and waist contact the lumbar support plate 121 in a seated position, the lumbar support plate 121 can adaptively rotate around the pivot relative to the support frame 122; the support frame 122 can generate axial elastic displacement under the action of the first elastic element 13 and rebound to its original position after the external force decreases, so that the lumbar support assembly 12 provides continuous support and rebound for different body shapes and sitting posture changes. The wrap-around portions on both sides of the lumbar support plate 121 provide wrap-around support for the waist to improve lateral support stability and comfort.

[0076] Handrail 2 hand support position adjustment: The user pushes the sliding cover 42 along the length of the handrail 2, so that the sliding cover 42 slides relative to the base 41; during the sliding process, the elastic protrusion 51 on the side wall of the limiting guide block 5 selectively engages or disengages between each first positioning groove 52, thereby achieving segmented positioning; when the sliding cover 42 reaches the appropriate position, the positioning is maintained by the cooperation of the elastic protrusion 51 and the corresponding first positioning groove 52.

[0077] Headrest 3 height and angle adjustment: The user applies a vertical adjustment force to the headrest assembly 7, causing the positioning core plate 73 to slide up and down along the guide channel 63; the positioning end of the elastic positioning member 731 selectively engages between the second positioning grooves 611, realizing the graded adjustment and positioning of the headrest 3 height. The user can also rotate the headrest body 72 around the pivot to adjust the headrest angle. When the headrest body 72 rotates to the limit angle, the limit baffle 81 and the lifting bracket 71 cooperate to limit its rotation range to avoid excessive rotation.

[0078] Through the above adjustments and usage process, the office chair can achieve adjustable and adaptive support in terms of seat height, backrest 1 tilt, lumbar support component 12 support, armrest 2 position, and headrest 3 height / angle, so as to meet the comfort needs of different users and different working conditions.

Claims

1. A headrest, comprising a clamping assembly for secure mounting on a chair back and a headrest assembly, characterized in that: The clamping assembly includes a front housing and a rear housing connected to each other, and the front housing and the rear housing enclose a vertical guide channel. The front housing has a plurality of second positioning grooves spaced vertically on the side facing the guide channel. The headrest assembly includes a lifting bracket and a headrest body. The lifting bracket is rotatably connected to the headrest body via a rotating shaft. The lifting bracket is sleeved on the outside of the clamping assembly. A positioning core plate is fixedly provided in the middle of the inner cavity of the lifting bracket. The positioning core plate passes through the guide channel and can slide up and down along the guide channel. The positioning core plate is provided with an elastic positioning element. Under the action of elastic force, the elastic positioning element abuts against and engages in the second positioning groove to realize the lifting adjustment and positioning of the headrest assembly relative to the clamping assembly.

2. The headrest according to claim 1, characterized in that: The clamping assembly also includes a lower pressure plate connected to the bottom of the rear housing. The front end of the lower pressure plate extends forward to form a lower clamping part, and the top of the front housing extends forward to form an upper clamping part. The upper clamping part and the lower clamping part cooperate to form a C-shaped clamping space for clamping the chair back.

3. The headrest according to claim 1, characterized in that: The top of the lifting bracket is provided with a rotating groove. The headrest body includes a connecting seat and a headrest frame. The lower part of the connecting seat is rotatably installed in the rotating groove through a damping shaft. The front end of the connecting seat is fixedly connected to the headrest frame. The rear end of the connecting seat extends to form a limiting baffle. When the headrest body rotates to the limit angle, the limiting baffle abuts against the top surface of the lifting bracket to limit the rotation angle of the headrest body.

4. The headrest according to claim 1, characterized in that: The elastic positioning element is an elastic sheet. The surface of the positioning core plate is provided with an installation groove. The elastic sheet is fixedly installed in the installation groove. The elastic sheet has a positioning protrusion on one side facing the front housing. The positioning protrusion pushes outward and is inserted into the second positioning groove under the elastic force of the elastic sheet itself.

5. The headrest according to claim 1, characterized in that: The side wall of the guide channel is provided with a vertical guide groove, and the positioning core plate is provided with a guide slider corresponding to the position of the guide groove. The guide slider slides in the guide groove to limit the left and right swaying of the lifting bracket.

6. The headrest according to claim 3, characterized in that: The headrest is an arc-shaped frame, and an elastic mesh is stretched on the arc-shaped frame, forming a breathable headrest support surface between the elastic mesh and the arc-shaped frame.

7. An office chair, characterized in that: The chair includes a backrest, a seat cushion, a base assembly, armrests, and a headrest as described in any one of claims 1-6. The seat cushion is disposed on the base assembly, the backrest is connected to the seat cushion, the headrest is mounted on the top of the backrest, and the armrests are respectively mounted on both sides of the seat cushion. The base assembly is provided with a backrest tilt adjustment mechanism and an electric lifting drive device.

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