CN220088987U - Headrest adjusting structure of office chair - Google Patents

Abstract

The headrest adjusting structure of the office chair comprises a headrest part, a chair back connecting seat, a headrest connecting seat and a support arm, wherein the headrest part comprises a headrest frame and a middle cover plate; one end of the support arm is rotatably connected to the headrest connecting seat; the upper portion of back of chair connecting seat is equipped with two fixed arms, is equipped with the first branch arm of inserting between two fixed arms on the support arm, adopt first pivot rotatable coupling between fixed arm and the first branch arm, at least one the fixed arm with be provided with an angle locking structure between the first branch arm. The utility model uses the angle locking structure to strengthen the retention force of the locking support arm, reduces the occurrence of the swinging displacement phenomenon of the support arm, ensures that the support arm is stably kept at a fixed position to support the headrest part, and ensures the comfort level of the user depending on the headrest part.

Description

Headrest adjusting structure of office chair

Technical Field

The utility model relates to the technical field of office chairs, in particular to a headrest adjusting structure of an office chair.

Background

Office chairs are various chairs equipped for convenience in daily work and social activities. Currently, there are many methods for controlling the flow of liquid. In order to improve the use comfort of office chairs, more and more office chairs are provided with a headrest, and the headrest is generally fixed at the upper end of the chair back of the office chair, so that the head of a user depends on the use.

In the prior art, in order to make the headrest capable of meeting the use requirements of different users, the headrest of the current office chair generally has a position adjusting function, for example, the improved structure of the headrest adjusting device of the office chair disclosed in Chinese patent with publication number CN214179805U is that a headrest capable of adjusting the height is arranged in the middle of the upper end of a chair back, a positioning chute is arranged in the middle of the headrest, a sliding block is arranged in the middle of the headrest and slides up and down along the positioning chute, and a continuous concave-convex embedding part is arranged on one side of the inner side of the positioning chute; the slider is provided with a convex part which can be elastically embedded with the continuous concave-convex embedded part at the corresponding position of the continuous concave-convex embedded part, and the side end of the slider and one end of a support arm can be pivoted and fixed together in a rotatable manner; the other end of the support arm is pivoted and fixed in the middle of the upper end of the chair back in a rotatable manner. The technical scheme ensures that the head of a person with shorter or higher height can be completely leaned on the headrest, thereby meeting the head leaning requirements of different users.

However, in this technical scheme, there is no angle locking structure between the pivot fixing portion of the support arm and the chair back, the angle of the support arm on the pivot fixing portion of the chair back is limited only by the friction between the pivot fixing portion of the support arm and the chair back, the retention force of this structure is insufficient, and the phenomenon of swing displacement of the support arm is easily caused when the chair back is used for a long time, so that the position of the headrest is changed, and thus the head of the user cannot be well relied on, and the use experience of the user is affected.

Disclosure of Invention

In order to overcome the defects in the prior art, the utility model provides a headrest adjusting structure of an office chair.

The technical scheme adopted for solving the technical problems is as follows:

the utility model provides a headrest adjusting structure of office chair, includes headrest part, back of the chair connecting seat, headrest connecting seat, support arm, headrest part includes headrest frame and middle apron, the inner circle of headrest frame is equipped with middle pedestal, middle apron is installed on the front end of middle pedestal, be formed with between middle pedestal and the middle apron and dodge the space, the headrest connecting seat crosses dodge the space, be equipped with high locking structure between middle pedestal and the headrest connecting seat; one end of the support arm is rotatably connected to the headrest connecting seat; the method is characterized in that: the upper part of the chair back connecting seat is provided with two fixed arms, the support arm is provided with a first sub-arm inserted between the two fixed arms, the fixed arms and the first sub-arm are rotatably connected by adopting a first rotating shaft, and at least one angle locking structure for locking the support arm is arranged between the fixed arm and the first sub-arm; the fixing arm is provided with a mounting through hole penetrating from left to right, the mounting through hole comprises a first groove and a first hole groove which are communicated with each other, and one side of the first sub-arm is provided with a second hole groove corresponding to the first hole groove; the angle locking structure comprises a first fluted disc arranged in the second hole groove in a positioning way, a second fluted disc movably arranged in the first hole groove, and an angle locking spring for pushing the second fluted disc to be meshed with the first fluted disc, wherein the angle locking spring is arranged in the first hole groove and pushes the second fluted disc to move close to the first fluted disc through elasticity.

In the utility model, a first rotation stopping groove is arranged in the second hole groove, and a first rotation stopping block which is matched and inserted in the first rotation stopping groove is arranged on the first fluted disc; the first hole groove is internally provided with a second rotation stopping groove, the second rotation stopping groove extends along the axial direction of the first hole groove, and the second fluted disc is provided with a second rotation stopping block which is in sliding fit with the second rotation stopping groove.

In the utility model, a first rotation limiting groove for limiting the rotation amplitude of the support arm is arranged on one side of the first arm facing the fixed arm, and a first rotation limiting block which moves in the first rotation limiting groove is arranged on the fixed arm.

In the utility model, the upper end of the support arm is provided with two second sub-arms, and the two second sub-arms are respectively and rotatably connected with the left end and the right end of the headrest connecting seat by adopting a first bolt.

In the utility model, the headrest connecting seat comprises a rotary convex part, the second arm is provided with a rotary groove, the rotary convex part is rotationally matched in the rotary groove, and the screw section of the first bolt passes through the second arm to be in threaded connection with the rotary convex part.

In the utility model, a second rotation limiting groove for limiting the rotation amplitude of the headrest connecting seat is arranged in the rotation groove, and a second rotation limiting block which moves in the second rotation limiting groove is arranged on the periphery of the rotation convex part.

In the utility model, the middle seat body is provided with a height gear array, and the height gear array comprises a plurality of height gear grooves which are arranged from top to bottom; the middle plate body of the headrest connecting seat is provided with a mounting hole groove at the rear side, and the mounting hole groove is internally provided with a height locking structure; the height locking structure comprises a height locking piece which can movably extend out of the matching groove and a height locking spring which drives the height locking piece to be inserted into one of the height gear grooves.

In the utility model, the rear side of the middle cover plate is provided with the lifting guide groove, and the front side of the middle plate body of the headrest connecting seat is provided with the first guide part which is in sliding guide fit in the lifting guide groove.

In the utility model, the front end of the chair back connecting seat is integrally formed and provided with two hook parts hooked on the chair back frame and a chair back connecting part for connecting with the chair back frame by adopting a fastener.

The utility model has the beneficial effects that:

1. according to the utility model, the angle locking structure for locking the support arm is arranged between the fixed arm and the first sub-arm, so that the retention force for locking the support arm is enhanced by utilizing the two angle locking structures, the occurrence of the swing displacement phenomenon of the support arm is reduced, the support arm is stably kept at a fixed position to support the headrest component, and the comfort level of a user depending on using the headrest component is ensured;

2. according to the utility model, the first rotation limiting groove of the first arm and the first rotation limiting block of the fixed arm are utilized to carry out combined limiting, so that the limit of the rotation amplitude of the support arm is realized, the second rotation limiting groove of the second arm and the second rotation limiting block of the headrest connecting seat are utilized to carry out combined limiting, the limit of the rotation amplitude of the headrest connecting seat is realized, the rotation amplitudes of the support arm and the headrest connecting seat are reduced, and the headrest connecting seat is beneficial to a user to quickly adjust the headrest part to a required position and then use the headrest part.

Drawings

The utility model is further described below with reference to the drawings and embodiments:

FIG. 1 is a perspective view of a seat back attachment base attached to a seat back frame;

FIG. 2 is a cross-sectional view of the connection of the seatback connecting base with the seatback frame;

FIG. 3 is an exploded view of the first embodiment;

FIG. 4 is an exploded view of the first and second toothed plates;

FIG. 5 is a schematic diagram of a combination of a first toothed disc and a second toothed disc;

FIG. 6 is a schematic diagram illustrating the cooperation of the first rotational stop block and the first rotational stop slot;

FIG. 7 is a schematic diagram illustrating the cooperation of the second rotational stop block and the second rotational stop slot;

fig. 8 is a perspective view of the headrest frame;

FIG. 9 is an exploded view of the headrest connection seat and the intermediate cover plate;

FIG. 10 is a schematic structural view of a height lock structure;

fig. 11 is a schematic view of the structure of the present utility model applied to an office chair.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present utility model more clear, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model.

Referring to fig. 1 to 11, a headrest adjusting structure of an office chair comprises a backrest connecting seat 1, a headrest connecting seat 2, a support arm 3 and a headrest part, wherein the headrest part comprises a headrest frame 4 and a middle cover plate 5; the inner circle of headrest frame 4 is equipped with rather than the intermediate seat body 41 of integrated into one piece setting, intermediate cover plate 5 installs on intermediate seat body 41's front end, be formed with between intermediate seat body 41 and the intermediate cover plate 5 and dodge space 100, headrest connecting seat 2 transversely dodge space 100, be equipped with high locking structure between intermediate seat body 41 and the headrest connecting seat 2, high locking structure is used for locking headrest parts's high position.

One end of the support arm 3 is rotatably connected to the headrest connecting seat 2, two fixing arms 13 are integrally formed on the upper portion of the chair back connecting seat 1, a first sub-arm 31 inserted between the two fixing arms 13 is integrally formed on the support arm 3, the fixing arms 13 and the first sub-arm 31 are rotatably connected through a first rotating shaft, the first rotating shaft is a fixing bolt 6, an angle locking structure for locking the support arm 3 is arranged between each fixing arm 13 and the first sub-arm 31, so that the retention force of the locking support arm 3 is enhanced by using the two angle locking structures, and the swinging displacement phenomenon of the support arm 3 is reduced.

In addition, since two angle locking structures are adopted to enhance the retention force of the locking arm 3, friction can be generated between the fixed arm 13 and the first sub-arm 31 without contact; of course, if necessary, the fixing bolt 6 may be screwed to make the fixing arm 13 press against the first arm 31, so that friction may be generated during the movement of the arm 3, and the effect of improving the retention force of the locking arm 3 may be achieved. In other embodiments, an angle locking structure may be provided between only one of the fixing arms 13 and the first sub-arm 31, and the retaining force provided by the angle locking structure may be set to be sufficiently large, so that the elastic force of the angle locking spring 73 may be increased, and the second toothed disc 72 and the first toothed disc 71 may be meshed with each other by using the elastic force of the angle locking spring 73 to be more compact.

As a preferred embodiment, the backrest connecting seat 1 is used for connecting with a backrest frame 200 of an office chair backrest, two hook portions 11 hooked on the backrest frame 200 and a backrest connecting portion 12 for connecting with the backrest frame 200 by using a fastener 300 are integrally formed at the front end of the backrest connecting seat 1, backrest connecting holes for matching with the fastener 300 are formed in the backrest connecting portion 12, and the fastener 300 is a bolt; after the two hooking portions 11 are hooked on the top end of the back frame 200, the back connecting portion 12 is inserted into the inner ring of the back frame 200, and then the screw section of the fastener 300 is connected with the back frame 200 through the back connecting hole, thereby fixing the back connecting seat 1 to the back frame 200.

As a preferred embodiment, the fixing arm 13 is provided with a mounting through hole penetrating from left to right, the mounting through hole comprises a first groove 131 and a first hole groove 132 which are communicated with each other, and a side of the first sub-arm 31 facing the fixing arm 13 is provided with a second hole groove 311 corresponding to the first hole groove 132; the angle locking structure comprises a first fluted disc 71 positioned and installed in a second hole groove 311, a second fluted disc 72 movably arranged in a first hole groove 132, and an angle locking spring 73 for pushing the second fluted disc 72 to be meshed with the first fluted disc 71, wherein the angle locking spring 73 is arranged in the first hole groove 132 and pushes the second fluted disc 72 to move close to the first fluted disc 71 along the axial direction of the first hole groove 132 through elastic force. When the angle locking spring 73 pushes the second toothed disc 72 to engage with the first toothed disc 71 by elastic force, the angle of the arm 3 is locked.

As a preferred embodiment, the second hole slot 311 is provided with a first rotation stopping slot 312, the first toothed disc 71 is provided with a first rotation stopping block 711 which is matched and inserted in the first rotation stopping slot 312, and the first toothed disc 71 can not rotate in the second hole slot 311 through the matching between the first rotation stopping slot 312 and the first rotation stopping block 711, so that the angle locking structure locks the angle.

In this embodiment, two first rotation stopping grooves 312 are uniformly distributed on the wall of the second hole groove 311, the first rotation stopping blocks 711 are integrally formed and disposed on the outer circumferential surface of the first toothed disc 71, and two first rotation stopping blocks 711 are respectively and cooperatively installed in the two first rotation stopping grooves 312.

As a preferred embodiment, a second rotation stopping groove 733 is disposed in the first hole groove 132, the second rotation stopping groove 733 extends along the axial direction of the first hole groove 132, a second rotation stopping block 721 slidably fitted in the second rotation stopping groove 733 is disposed on the second toothed disc 72, and the second toothed disc 72 is not rotatable in the first hole groove 132 and is movable along the axial direction of the first hole groove 132 by the engagement between the second rotation stopping groove 733 and the second rotation stopping block 721, so that the angle locking structure locks the angle. In this embodiment, the second rotation stopping grooves 733 are four and uniformly distributed on the wall of the first hole groove 132, the second rotation stopping blocks 721 are integrally formed on the outer circumferential surface of the second toothed disc 72, the second rotation stopping blocks 721 are four and respectively slidably fit into the four second rotation stopping grooves 733, and the second rotation stopping blocks 721 and the second rotation stopping grooves 733 form a guiding structure that enables the second toothed disc 72 to axially move along the first hole groove 132.

As a preferred embodiment, each of the first grooves 131 is internally provided with a fixed spacer 8, the second toothed disc 72 and the first toothed disc 71 are respectively provided with a matching through hole for the screw section of the fixing bolt 6 to pass through, the second hole slot 311 is internally provided with a fixed screw hole, the screw section of the fixing bolt 6 passes through the fixed spacer 8, the second toothed disc 72 and the matching through holes on the first toothed disc 71 to be in threaded fit in the fixed screw hole, through the structure, the support arm 3 is rotatably mounted on the chair back connecting seat 1, and meanwhile, the support arm 3 can rotate and swing by an angle relative to the chair back connecting seat 1 by taking the fixing bolt 6 as a rotation center. In this embodiment, one end of the angle locking spring 73 abuts against the second toothed disc 72, and the other end abuts against the fixed spacer 8, so that the angle locking spring 73 can provide an elastic force for driving the second toothed disc 72 to approach the first toothed disc 71 and engage with the first toothed disc 71.

As a preferred embodiment, the first groove 131 is inserted with the fixed decorative cover 9, the fixed decorative cover 9 can shield the fixed spacer 8 and the fixed bolt 6, so that foreign objects are prevented from affecting the fixed spacer 8 and the fixed bolt 6, and meanwhile, the fixed decorative cover 9 also plays a role in decoration, and the attractiveness of the office chair is improved.

As a preferred embodiment, since the user pulls the arm 3 by hand to swing, all the situations that the overturning angle of the arm 3 is too large may occur, so that the user needs to repeatedly fine tune the arm 3 to adjust to the required requirement, thereby being unfavorable for the user to quickly adjust the headrest component, in order to avoid such situations, referring to fig. 3 and 6, a first rotation limiting groove 313 for limiting the rotation amplitude of the arm 3 is arranged on the side of the first sub-arm 31 facing the fixed arm 13, a first rotation limiting block 133 moving in the first rotation limiting groove 313 is arranged on the fixed arm 13, and when the first rotation limiting block 133 abuts against one end of the first rotation limiting groove 313, the overturning angle of the arm 3 is indicated to be the maximum; when the first rotation limiting block 133 abuts against the other end of the first rotation limiting groove 313, it means that the support arm 3 is turned to a minimum angle. The rotation amplitude of the support arm 3 can be limited to be 40-65 degrees, and the rotation amplitude is most preferably 54 degrees through the structure, so that the condition that the turnover angle of the support arm 3 is overlarge is avoided.

As a preferred embodiment, two second sub-arms 32 are provided at the upper ends of the support arm 3, and the two second sub-arms 32 are rotatably connected to the left and right ends of the headrest connection seat 2 by using first bolts 9, respectively. Further, in order to improve the stability of the fit between the headrest seat and the second arm 32, the headrest connecting seat 2 includes a rotation protrusion 21, the second arm 32 is provided with a rotation groove 321 for the rotation of the rotation protrusion 21, the cross-sectional shapes of the rotation protrusion 21 and the rotation groove 321 are both in a shape of a truncated cone, and the rotation protrusion 21 is rotationally fitted in the rotation groove 321; the screw section of the first bolt 9 passes through the second arm 32 to be in threaded connection with the rotary protruding portion 21, specifically, a connecting screw hole is formed in the rotary protruding portion 21, a connecting through hole is formed in the second arm 32, and the screw section of the first bolt 9 passes through the connecting through hole to be in threaded connection with the connecting screw hole, so that the headrest connecting seat 2 is connected with the second arm 32.

As a preferred embodiment, since there is no angular locking structure between the headrest connecting seat 2 and the second arm 32, the degree of freedom of the headrest connecting seat 2 is relatively large during use, allowing the headrest member to rotate somewhat by the weight of the user's head following the user's head when being relied upon by the user, thereby allowing the headrest member to better cradle the user's head. However, since the normal use of the headrest member is easily affected by the excessive degree of freedom of the headrest connecting seat 2, in order to avoid this, a second rotation limit groove 322 for limiting the rotation range of the headrest connecting seat 2 is provided in the rotation groove 321, and a second rotation limit block 211 movable in the second rotation limit groove 322 is provided on the outer periphery of the rotation protrusion 21, as shown in fig. 3 and 7.

When the second rotation limiting block 211 abuts against the other end of the second rotation limiting groove 322, it indicates that the headrest connecting seat 2 is turned to the minimum angle. The rotation range of the headrest connecting seat 2 can be limited to be 30-50 degrees, and most preferably 45 degrees through the structure, so that the influence of the excessive rotation range of the headrest connecting seat 2 on headrest components is avoided. In addition, in order to prevent the headrest member from being turned down by gravity when the headrest member does not support the head of the user, a soft rubber pad is provided in the rotation groove 321, one end of the soft rubber pad is in contact with the groove wall of the rotation groove 321, the other end of the soft rubber pad is in contact with the end surface of the rotation protrusion 21, the soft rubber pad is used for providing a certain damping to prevent the headrest member from being turned down by gravity when the headrest member does not support the head of the user, and the soft rubber pad is not shown in the drawing.

Further, by tightening the first bolt 9, the friction between the rotation convex portion 21 and the groove wall of the rotation groove 321 can also play a role of increasing damping, preventing the headrest member from turning down by gravity when the headrest member does not hold the head of the user.

As a preferred embodiment, the headrest connection seat 2 further includes a middle plate 22, two integrally formed connection protrusions 23 disposed at left and right ends of the middle plate 22, the middle plate 22 traverses the avoidance space 100, and the rotation protrusion 21 is disposed on a side of the connection protrusion 23 away from the middle plate 22.

As a preferred embodiment, the middle seat 41 is provided with two height gear arrays, and each height gear array comprises a plurality of height gear slots 411 arranged from top to bottom; in this embodiment, the middle seat 41 is provided with two engaging protruding strips arranged in a left-right arrangement, and the plurality of height position slots 411 of each height position array are formed on the engaging protruding strips from top to bottom.

Further, two mounting hole slots 221 are formed in the rear side of the middle plate 22 of the headrest connecting seat 2, the two mounting hole slots 221 are arranged in a left-right arrangement mode, each mounting hole slot 221 corresponds to a height gear array, one height locking structure is arranged in each mounting hole slot 221, the height locking structure comprises a height locking piece 10 which can movably extend out of a matching groove, a height locking spring 20 for driving the height locking piece 10 to be inserted into one of the height gear slots 411, one end of the height locking spring 20 abuts against the slot wall of the mounting hole slot 221, and the other end of the height locking spring 20 abuts against the height locking piece 10. Further, the height lock 10 is a ball or a cylinder with a half round head, preferably a cylinder with a half round head.

As a preferred embodiment, two mounting protruding blocks 51 are disposed on the rear side of the middle cover plate 5 and located at the upper end and the lower end of the middle cover plate 5, two mounting grooves 412 are disposed on the front side of the middle seat body 41, the two mounting protruding blocks 51 are respectively clamped into the two mounting grooves 412, so that the middle cover plate 5 is positioned on the middle seat body 41, and a second bolt penetrating through the mounting protruding blocks 51 and in threaded connection with the middle seat body 41 is inserted into the middle cover plate 5.

As a preferred embodiment, the rear side of the middle cover plate 5 is provided with a lifting guide groove 52, and the front side of the middle plate body 22 is provided with a first guide portion 222 slidably guided to fit in the lifting guide groove 52. Further, the rear side of the middle plate 22 is provided with a guiding protrusion 223, a guiding chute is formed between the guiding protrusion 223 and the connecting protrusion 23, and the middle seat 41 is provided with a guiding protruding strip 413 slidingly engaged in the guiding chute, so that the headrest component can be better engaged on the headrest connecting seat 2.

The foregoing is only a preferred embodiment of the present utility model, and all technical solutions for achieving the object of the present utility model by substantially the same means are included in the scope of the present utility model.

Claims (9)

1. The utility model provides a headrest adjusting structure of office chair, includes headrest part, back of the chair connecting seat (1), headrest connecting seat (2), support arm (3), headrest part includes headrest frame (4) and middle apron (5), the inner circle of headrest frame (4) is equipped with middle pedestal (41), middle apron (5) are installed on the front end of middle pedestal (41), be formed with between middle pedestal (41) and middle apron (5) and dodge space (100), headrest connecting seat (2) transversely dodge space (100), be equipped with high locking structure between middle pedestal (41) and headrest connecting seat (2); one end of the support arm (3) is rotatably connected to the headrest connecting seat (2); the method is characterized in that: the upper part of the chair back connecting seat (1) is provided with two fixed arms (13), the support arm (3) is provided with a first sub-arm (31) inserted between the two fixed arms (13), the fixed arms (13) and the first sub-arm (31) are rotatably connected by adopting a first rotating shaft, and at least one angle locking structure for locking the support arm (3) is arranged between the fixed arms (13) and the first sub-arm (31); the fixing arm (13) is provided with a mounting through hole penetrating from left to right, the mounting through hole comprises a first groove (131) and a first hole groove (132) which are communicated with each other, and one side of the first sub-arm (31) is provided with a second hole groove (311) corresponding to the first hole groove (132); the angle locking structure comprises a first fluted disc (71) which is installed in a second hole groove (311) in a positioning mode, a second fluted disc (72) which is movably arranged in a first hole groove (132), and an angle locking spring (73) which pushes the second fluted disc (72) to be meshed with the first fluted disc (71), wherein the angle locking spring (73) is arranged in the first hole groove (132) and pushes the second fluted disc (72) to move close to the first fluted disc (71) through elasticity.

2. The headrest adjusting structure of an office chair according to claim 1, wherein: a first rotation stopping groove (312) is formed in the second hole groove (311), and a first rotation stopping block (711) which is inserted in the first rotation stopping groove (312) in a matching way is arranged on the first fluted disc (71); the first hole groove (132) is internally provided with a second rotation stopping groove (733), the second rotation stopping groove (733) extends along the axial direction of the first hole groove (132), and the second fluted disc (72) is provided with a second rotation stopping block (721) which is in sliding fit with the second rotation stopping groove (733).

3. The headrest adjusting structure of an office chair according to claim 1, wherein: the first rotation limiting groove (313) used for limiting the rotation amplitude of the support arm (3) is formed in one side, facing the fixed arm (13), of the first sub-arm (31), and the first rotation limiting block (133) moving in the first rotation limiting groove (313) is formed in the fixed arm (13).

4. The headrest adjusting structure of an office chair according to claim 1, wherein: the upper end of the support arm (3) is provided with two second sub-arms (32), and the two second sub-arms (32) are respectively rotatably connected with the left end and the right end of the headrest connecting seat (2) by adopting a first bolt (9).

5. The headrest adjusting structure of an office chair according to claim 4, wherein: the headrest connecting seat (2) comprises a rotary protruding portion (21), a rotary groove (321) is formed in the second sub-arm (32), the rotary protruding portion (21) is rotatably matched in the rotary groove (321), and a screw rod section of the first bolt (9) penetrates through the second sub-arm (32) to be in threaded connection with the rotary protruding portion (21).

6. The headrest adjusting structure of an office chair according to claim 5, wherein: the rotation groove (321) is internally provided with a second rotation limiting groove (322) used for limiting the rotation amplitude of the headrest connecting seat (2), and the periphery of the rotation convex part (21) is provided with a second rotation limiting block (211) moving in the second rotation limiting groove (322).

7. The headrest adjusting structure of an office chair according to claim 1, wherein: the middle seat body (41) is provided with a height gear array, and the height gear array comprises a plurality of height gear slots (411) which are arranged from top to bottom; the rear side of the middle plate body (22) of the headrest connecting seat (2) is provided with a mounting hole groove (221), and the mounting hole groove (221) is internally provided with a height locking structure; the height locking structure comprises a height locking piece (10) which can movably extend out of the matching groove, and a height locking spring (20) which drives the height locking piece (10) to be inserted into one of the height gear slots (411).

8. The headrest adjusting structure of an office chair according to claim 1, wherein: the rear side of the middle cover plate (5) is provided with a lifting guide groove (52), and the front side of the middle plate body (22) of the headrest connecting seat (2) is provided with a first guide part (222) which is in sliding guide fit in the lifting guide groove (52).

9. The headrest adjusting structure of an office chair according to claim 1, wherein: the front end of the chair back connecting seat (1) is integrally formed and provided with two hook parts (11) hooked on the chair back frame (200) and a chair back connecting part (12) connected with the chair back frame (200) by adopting a fastener (300).