A folding chair

Abstract

The application provides a folding chair, comprising a seat, a backrest and a pivot connected between the seat and the backrest, two locking assemblies, each of the locking assemblies comprising a limiting structure and a positioning structure, so that the backrest is rotatably fixed at at least one predetermined angle relative to the seat, a transmission assembly comprising an operating member and a linkage transmission member, the operating member comprising an operating part for user operation and a driving part connected with the linkage transmission member, the linkage transmission member being translatably arranged on the backrest, the operating member driving the linkage transmission member to translate through the driving part when the operating member moves, and the translation of the linkage transmission member driving the two locking assemblies to synchronously act, so that the two positioning structures simultaneously cooperate with or are separated from the corresponding limiting structures. The application is suitable for mobile service scenes requiring frequent carrying and quick unfolding and storage, and a user can reliably lock or unlock the backrest angle through single operation.

Description

Technical Field

[0001] This invention relates to the field of folding chair technology, and more specifically to a folding chair. Background Technology

[0002] Currently, folding chairs are increasingly widely used in outdoor work, mobile services, and emergency rescue scenarios. Take mobile barbers as an example: they need to operate in various outdoor or mobile settings such as parks, commercial districts, communities, nursing homes, and military camps, thus placing multiple functional demands on folding chairs, including portability, quick unfolding and storage, and adjustable and locking backrest angles. While existing folding chairs generally have folding capabilities, they often fall short in terms of backrest angle adjustment and locking.

[0003] Existing folding chair backrest locking mechanisms mostly employ a single-sided pin or dual-sided independent pin structure. In the single-sided pin scheme, users need to operate the locking components on both sides separately to lock or unlock the backrest, which is cumbersome and inefficient. While the dual-sided independent pin scheme achieves dual-sided locking, the two pins are controlled independently, making simultaneous insertion and disengagement from the lock holes impossible. This can easily lead to backrest tilting and unreliable locking due to asynchronous locking on both sides. Furthermore, some schemes using rigid pivot connections for dual-sided locking mechanisms, although achieving dual-sided linkage, rely on pure rotational motion, limiting the flexibility of the transmission path layout and making it difficult to achieve efficient coordination with linear motion locking actuators. Summary of the Invention

[0004] This invention provides a folding chair to solve the problems of cumbersome backrest locking operation and asynchronous locking on both sides in existing folding chairs.

[0005] This invention provides a folding chair, including a seat, a backrest, and a pivot connecting the seat and the backrest, and further comprising: Two locking components are symmetrically arranged on the left and right sides of the folding chair. Each locking component includes a limiting structure on one of the seat and the backrest, and a positioning structure on the other. The positioning structure is used to cooperate with the limiting structure so that the backrest is rotatably fixed at at least a predetermined angle relative to the seat. A transmission assembly, disposed on the chair back, includes an operating component and a linkage transmission component; The operating component is movably mounted on the chair back and includes an operating part for user operation and a drive part connected to the linkage transmission component. The linkage transmission component is slidably mounted on the chair back, and its two ends are respectively connected to the two locking components; When the operating component moves, it drives the linkage transmission component to translate through the driving part. The translation of the linkage transmission component causes the two locking components to move synchronously, so that the two positioning structures and the corresponding limiting structures can engage or disengage at the same time.

[0006] Furthermore, the linkage transmission component includes an active translation component located on one side, a driven translation component located on the other side, and a transmission component connected between the active translation component and the driven translation component. The transmission component is used to drive the driven translation component so that the driven translation component moves away from or closer to the active translation component synchronously.

[0007] Furthermore, the active translation member is provided with a first rack, and the driving part of the operating member is an active gear that meshes with the first rack.

[0008] Furthermore, the linkage transmission component includes a transmission gear, the active translation component also includes a second rack, and the driven translation component is provided with a third rack; the second rack meshes with one side of the transmission gear, and the third rack meshes with the other side of the transmission gear.

[0009] Furthermore, the active translation component is a first Z-shaped translation component, which includes an active translation component body connected to a locking assembly on one side, a first lower connecting rod extending from the active translation component body towards the center, a first upper connecting rod connected to the transmission component, and a first longitudinal connecting rod connecting the first lower connecting rod and the first upper connecting rod. A first rack is provided above the first lower connecting rod, and a second rack is provided below the first upper connecting rod. The lower side of the active gear meshes with the first rack of the first lower connecting rod; the upper side of the transmission gear meshes with the second rack of the first upper connecting rod. The driven translation component includes a driven translation component body connected to a locking assembly on the other side, and a third rack meshing with the bottom of the transmission gear.

[0010] Furthermore, the driven translation member is a second Z-shaped translation member, which includes a driven translation member body connected to the locking assembly on the other side, a second upper connecting rod extending from the driven translation member body towards the center, a second lower connecting rod connected to the transmission member, and a second longitudinal connecting rod connecting the second upper connecting rod and the second lower connecting rod; the third rack is disposed above the second lower connecting rod.

[0011] Furthermore, the chair back includes a chair back body located at the top and a sub-plate near the seat. The sub-plate includes a sub-plate housing. The locking assembly and the transmission assembly are slidably disposed within the sub-plate housing. The sub-plate housing has an upper inner wall surface and a lower inner wall surface. The upper end surfaces of the first upper connecting rod and the second upper connecting rod abut against the upper inner wall surface of the sub-plate housing, and the lower end surfaces of the first lower connecting rod and the second lower connecting rod abut against the lower inner wall surface of the sub-plate housing. The sub-plate housing includes an operating port for the operating component to extend out, and also includes a lateral opening for the positioning structure of the locking assembly to pass through.

[0012] Furthermore, the positioning structure includes an elastic pin and a positioning hole. The elastic pin includes a first pin body disposed on the active translation member body and the driven translation member body, and a first elastic member with one end fixed to the first pin body. The positioning hole is located on the side plate of the chair seat. The sub-plate housing includes a front cover, which includes front support brackets located on both sides and a rear support bracket located in the middle. The front support brackets are close to the front of the chair back, and the rear support brackets are close to the back of the chair back and are simultaneously abutted against the active translation component and the driven translation component. The active gear and the transmission gear are located on the back of the rear support bracket. The front end bracket is also provided with a top stop for fixing the other end of the first elastic member. The top stop extends backward from the front end bracket and has a through hole in the middle for the first pin body to pass through. The outer sides of the active translation component body and the driven translation component body are also formed with bent portions, and the first pin body is disposed in the bent portion and extends outward through the through hole. When the first elastic element is in a compressed state, and the bent portion is against the top stop, the first pin body extends out of the positioning hole under the tension of the first elastic element.

[0013] Furthermore, the folding chair also includes chair legs, each chair leg comprising a fixed leg tube and a telescopic inner tube, the telescopic inner tube being telescopically fitted inside the fixed leg tube; The fixed leg tube is provided with a locking assembly, which includes a pressing part, an L-shaped linkage member linked with the pressing part, and a locking pin provided on the L-shaped linkage member. The telescopic inner tube is provided with multiple adjustable locking holes spaced apart along its length. The fixed leg tube is provided with a leg tube housing with a reset cavity. The L-shaped linkage is disposed in the reset cavity. The first arm of the L-shaped linkage is abutted against the outer wall of the telescopic inner tube. The second arm of the L-shaped linkage is provided with the locking pin. The locking assembly also includes a reset spring disposed between the inner wall of the reset cavity and the second arm of the L-shaped linkage. The fixed leg tube surface is provided with a clearance hole at the corresponding position of the pressing part. The locking pin passes through the fixed leg tube and is inserted into the corresponding adjustment lock hole on the telescopic inner tube under the action of the return spring. When the pressing part is pressed, the L-shaped linkage drives the locking pin to exit the adjustment lock hole.

[0014] Furthermore, the folding chair also includes an external attachment, which is a shelf or footrest. The external attachment has an insert body, and the insert body has a first socket and a second socket. The opening of the first socket faces a first direction, and the opening of the second socket faces a second direction, wherein the first direction and the second direction are perpendicular to each other; When the folding chair is in the unfolded state, the external attachment is secured to the folding chair vertically through the first socket; When the folding chair is in the folded state, the external attachment is secured to the folding chair via the second connector.

[0015] This invention, through the arrangement of two locking components symmetrically distributed on the left and right sides of a folding chair, and a linkage transmission component slidably mounted on the backrest, allows the user to drive the linkage transmission component to move with a single operation. Simultaneously, both ends of the linkage transmission component engage or disengage the positioning and limiting structures on both sides, achieving simultaneous locking and unlocking of the backrest angle on both sides. This effectively avoids backrest tilting or unreliable locking caused by asynchronous locking on both sides. Furthermore, the movement of the operating component is converted into linear driving force through the translation of the linkage transmission component, resulting in a simple and efficient transmission path and reducing... The limited number of components helps the folding chair maintain a compact overall shape when folded. Furthermore, the arrangement of the operating components on the backrest and the movable linkage allows for intuitive force application and easy operation when adjusting the backrest angle, significantly improving usability. Based on this structure, the folding chair of this invention is particularly suitable for mobile service scenarios requiring frequent transport and rapid unfolding and storage, such as outdoor hairdressing, shopping malls, home services, nursing homes, and military camps. Users can reliably lock or unlock the backrest angle with a single operation, balancing portability and user comfort. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a perspective view of the folding chair in the unfolded state according to this embodiment, with the shelf and footrest in use. Figure 2 for Figure 1 A stereoscopic view from another perspective; Figure 3 for Figure 2 A partial view near the sub-board, with the back cover hidden in the image; Figure 4 This is a perspective view of the sub-board of the folding chair in this embodiment; Figure 5 This is a perspective view of the sub-board of the folding chair in this embodiment. Figure 6 for Figure 4 Exploded view; Figure 7 An exploded view showing the connection relationship between the operating components, active translation components, locking components, and the side panels of the seat and backrest. Figure 8 A 3D diagram of the storage shelf; Figure 9 A 3D diagram of the footrest; Figure 10 An exploded view of the chair legs; Figure 11 This is a perspective view of the folding chair in the folded state according to this embodiment. The shelf and footrest are in the storage state in the figure. Figure 12 This is a perspective view from the rear, showing the connection relationship between the height adjustment rod and the adjustment latch assembly in this embodiment. Figure 13 for Figure 12 A three-dimensional image from a frontal view; Figure 14 This is an exploded view of the adjusting latch assembly in this embodiment.

[0018] Labeling Explanation: 1. Operating component; 101. Operating part; 102. Drive part; 2. Linkage transmission component; 3. Active translation component; 31. First lower connecting rod; 311. First rack; 32. First upper connecting rod; 321. Second rack; 33. Active translation component body; 34. First longitudinal connecting rod; 4. Driven translation component; 41. Second lower connecting rod; 411. Third rack; 42. Second upper connecting rod; 43. Driven translation component body; 44. Second longitudinal connecting rod; 5. Chair 6. Backrest side panel; 7. Transmission gear; 8. Backrest body; 9. Sub-panel; 10. Operation port; 11. Side opening; 12. Rear cover; 13. Front cover; 14. Front support; 15. Rear support; 16. Top stop; 17. Elastic pin; 18. First pin body; 19. Elastic element; 10. Positioning hole; 11. Seat side panel; 12. Bending part; 13. Fixed leg tube; 14. Pressing part; 15. L-shaped linkage; 16. Locking pin; 17. 135. Return spring; 136. Clearance hole; 137. Leg tube housing; 138. Tube sleeve; 139. Notch; 14. Telescopic inner tube; 141. Adjustment lock hole; 15. Insert body; 151. First insertion port; 152. Second insertion port; 16. Footrest; 161. Footrest body; 162. Extension rod; 163. Connecting arm; 17. Pulley; 18. Shelf; 19. Height adjustment rod; 20. Adjustment lock assembly; 21. Lock housing; 211. Lateral... 212. Outer protective plate; 213. First parallel guide plate; 214. Baffle; 215. Second parallel guide plate; 216. Second longitudinal channel; 22. Locking inner housing; 221. First elevation; 222. Second elevation; 223. Connecting surface; 224. First longitudinal channel; 225. Lateral clearance notch; 226. Pin hole; 23. Locking fastener; 231. Third arm; 232. Fourth arm; 233. Press switch; 234. Second elastic element; 235. Pin. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first," "second," "third," and "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 invention based on the specific circumstances.

[0022] Please see Figures 1 to 11 This embodiment provides a folding chair, including a seat, a backrest, and a pivot (conventional structure, not shown in the figures) connecting the seat and the backrest, and further including: Two locking components are symmetrically arranged on the left and right sides of the folding chair. Each locking component includes a limiting structure on one of the seat and the backrest, and a positioning structure on the other. The positioning structure is used to cooperate with the limiting structure so that the backrest is rotatably fixed at at least a predetermined angle relative to the seat. The transmission assembly, located on the chair back, includes an operating component 1 and a linkage transmission component 2; The operating component 1 is movably disposed on the chair back and includes an operating part 101 for user operation and a driving part 102 connected to the linkage transmission component 2. The linkage transmission component 2 is slidably mounted on the chair back, and its two ends are respectively connected to the two locking components; When the operating component 1 moves, it drives the linkage transmission component 2 to translate through the driving part 102. The translation of the linkage transmission component 2 causes the two locking components to move synchronously, so that the two positioning structures and the corresponding limiting structures can cooperate or disengage at the same time.

[0023] In this embodiment, the pivot can be directly disposed between the backrest body 7 and the seat, or it can be disposed between the side plate 5 of the backrest and the side plate 11 of the seat, for rotating the backrest relative to the seat. Two locking components are used to lock / unlock the backrest and adjust its angle; these components are symmetrically arranged on the left and right sides of the folding chair. This symmetrical arrangement ensures that the backrest experiences balanced force when locked, preventing backrest tilting or swaying due to locking on one side.

[0024] The limiting structure, as the object being engaged, can be configured as multiple positioning holes 10 arranged along an arc, or as a single positioning hole or positioning groove; the positioning structure, as the active object being engaged, can be configured as a retractable pin or a latch. The engagement relationship between the limiting structure and the positioning structure is as follows: when the positioning structure is inserted into or engaged with the limiting structure, the angle of the chair back relative to the seat is fixed; when the positioning structure disengages from the limiting structure, the chair back can rotate freely around a pivot, thereby achieving angle adjustment or folding for storage.

[0025] As an optional rather than limiting solution, the limiting structure can be set on the seat and the positioning structure on the backrest; alternatively, the limiting structure can be set on the backrest and the positioning structure on the seat. In this embodiment, for the convenience of centralized arrangement and operation of the transmission components, it is preferable to set the entire transmission components on the backrest, so that the operating component 1 rotates synchronously with the backrest, and the user does not need to switch the operating position between the seat and the backrest when adjusting the backrest angle.

[0026] The linkage transmission component 2 is slidably mounted on the chair back, with its two ends connected to the locking components on the left and right sides, respectively. The slidability refers to the linkage transmission component 2 reciprocating along a straight line under the drive of the operating component 1, rather than rotating around a certain axis. This slidable motion differs from the existing rotary transmission method that uses a rigid pivot to achieve bilateral linkage, making the power transmission path simpler and more direct, and facilitating efficient cooperation with linearly moving locking actuators such as pins.

[0027] The movement of the operating component 1 can be rotational (such as a paddle rotating around its mounting axis) or linear (such as the reciprocating sliding of a push-pull handle). In this embodiment, the operating component 1 is preferably in the form of a paddle, allowing the user to drive the linkage transmission component 2 to translate by plucking the paddle. The direction of force is intuitive and the operation is convenient. When the user operates the operating component 1, the operating component 1 transmits the motion to the linkage transmission component 2 through the drive unit 102. The linkage transmission component 2 translates in a linear direction, and its two ends simultaneously drive the positioning structures on the left and right sides to engage or disengage synchronously with the corresponding limiting structures. Specifically, the two sides of the linkage transmission component 2 can simultaneously move closer or further apart, effectively avoiding problems such as backrest tilting, unreliable locking, or unlocking jamming caused by asynchronous locking on both sides.

[0028] Specifically, the linkage transmission component 2 includes an active translation component 3 located on one side, a driven translation component 4 located on the other side, and a transmission component connecting the active translation component 3 and the driven translation component 4. The transmission component is used to drive the driven translation component 4 so that the driven translation component 4 moves away from or closer to the active translation component 3 synchronously.

[0029] The aforementioned transmission component connects the active translation component 3 and the driven translation component 4, transmitting the translational motion of the active translation component 3 to the driven translation component 4, so that the two move away or move closer together synchronously according to a predetermined motion relationship. This master-slave drive transmission logic allows the operating component 1 to drive only one translation component, which in turn drives the other translation component to move synchronously via the transmission component. The structure is simple and the operation is convenient.

[0030] Furthermore, the active translation member 3 is provided with a first rack 311, and the driving part 102 of the operating member 1 is an active gear that meshes with the first rack 311.

[0031] In this embodiment, the driving part 102 of the operating component 1 is specifically a drive gear, and a first rack 311 is fixedly mounted on the active translation component 3. The drive gear and the first rack 311 mesh with each other. When the user operates the operating component 1, the operating component 1 drives the drive gear to rotate. Through the meshing action between the drive gear and the first rack 311, the rotational motion is converted into the linear translational motion of the first rack 311, thereby driving the active translation component 3 to translate in a straight line. The active translation component 3 and the driven translation component 4 are connected by a gear transmission mechanism. Compared with transmission methods such as pull wires, connecting rods, or pivots, the gear transmission mechanism has advantages such as precise transmission ratio, controllable stroke, good rigidity, and no elastic deformation.

[0032] Furthermore, the linkage transmission component 2 includes a transmission gear 6, the active translation component 3 also includes a second rack 321, and the driven translation component 4 is provided with a third rack 411; the second rack 321 meshes with one side of the transmission gear 6, and the third rack 411 meshes with the other side of the transmission gear 6.

[0033] In this embodiment, the transmission gear 6 of the linkage transmission component 2 is rotatably mounted on the chair back, with its axial position fixed relative to the chair back. That is, the transmission gear 6 only rotates without translation. The second rack 321 is fixedly mounted on the active translation component 3 and translates synchronously with it. The third rack 411 is fixedly mounted on the driven translation component 4 and translates synchronously with it. The second rack 321 meshes with one side (e.g., the upper side) of the transmission gear 6, and the third rack 411 meshes with the other side (e.g., the lower side) of the transmission gear 6. When the operating component 1 drives the active translation component 3 to translate, the second rack 321 translates accordingly, driving the transmission gear 6 to rotate through meshing. The rotation of the transmission gear 6 then drives the third rack 411 to translate through meshing, thereby causing the driven translation component 4 to translate.

[0034] Since the second rack 321 and the third rack 411 are located on opposite sides of the transmission gear 6 and mesh with different tooth sides of the transmission gear 6, their translational directions are opposite, allowing them to move away or move closer synchronously. Through the above structure, the driving force on one side of the operating member 1 is precisely transmitted to the opposite side of the folding chair, realizing the synchronous operation of the double-sided locking components.

[0035] Furthermore, the active translation member 3 is a first Z-shaped translation member, which includes an active translation member body 33 connected to a locking assembly on one side, a first lower connecting rod 31 extending from the active translation member body 33 toward the center, a first upper connecting rod 32 connected to the transmission member, and a first longitudinal connecting rod 34 connecting the first lower connecting rod 31 and the first upper connecting rod 32. A first rack 311 is provided above the first lower connecting rod 31, and a second rack 321 is provided below the first upper connecting rod 32. The lower side of the drive unit 102 meshes with the first rack 311 of the first lower connecting rod 31. The upper side of the transmission gear 6 meshes with the second rack 321 of the first upper connecting rod 32. The driven translation member 4 includes a driven translation member body 43 connected to a locking assembly on the other side, and a third rack 411 meshing with the bottom of the transmission gear 6.

[0036] In this embodiment, the upper link, lower link, and longitudinal link connecting the two of the Z-shaped translation member form a "Z" shape. The active translation member body 33 is located at the outer end of the first Z-shaped translation member and is connected to the locking assembly on the corresponding side to drive the positioning structure on that side to move.

[0037] The first lower link 31 extends from the active translation member body 33 toward the center of the folding chair, and a first rack 311 is provided above it, which meshes with the lower side of the drive unit 102. The first upper link 32 extends from the first longitudinal link 34 toward the center, but its position is higher than that of the first lower link 31.

[0038] As a preferred option rather than a limitation, both the first lower connecting rod 31 and the first upper connecting rod 32 are horizontally extending rod-shaped or plate-shaped structures, arranged vertically at intervals and parallel to each other. A first longitudinal connecting rod 34 is obliquely connected between the two, and the first longitudinal connecting rod 34 is close to the outer end of the first Z-shaped translation member in a downward direction, making the overall structure of the first Z-shaped translation member "Z". This Z-shaped structure allows the first rack 311 on the first lower connecting rod 31 and the second rack 321 on the first upper connecting rod 32 to be located at different vertical heights, thus allowing two independent rack-gear meshing pairs to be arranged within the limited space of the seat back—the drive unit 102 meshes with the first rack 311 below, and the transmission gear 6 meshes with the second rack 321 above. The two meshing pairs are arranged vertically at intervals, without interfering with each other, resulting in a clear transmission path and a compact structure.

[0039] The driven translator body 43 is located on the other side of the folding chair and is connected to the locking assembly on the corresponding side. The third rack 411 meshes with the bottom of the transmission gear 6. When the transmission gear 6 is driven to rotate by the second rack 321 on the driving translator 3, the bottom teeth of the transmission gear 6 drive the third rack 411 to translate through meshing. The third rack 411 drives the driven translator body 43 to translate, thereby making the driven translator 4 and the driving translator 3 move synchronously.

[0040] As an illustration rather than a limitation, the Z-shaped structure of the first Z-shaped translation member creates a longitudinal gap between the first upper connecting rod 32 and the first lower connecting rod 31, which precisely accommodates the arrangement space of the transmission gear 6 and the drive unit 102. This arrangement makes full use of the clearance space of the Z-shaped structure, achieving a compact layout of the two-stage gear and rack transmission structure without increasing the horizontal dimension.

[0041] As a preferred embodiment rather than a limitation, the driven translation member 4 is a second Z-shaped translation member, which includes a driven translation member body 43 connected to the locking assembly on the other side, a second upper connecting rod 42 extending from the driven translation member body 43 toward the center, a second lower connecting rod 41 connected to the transmission member, and a second longitudinal connecting rod 44 connecting the second upper connecting rod 42 and the second lower connecting rod 41; the third rack 411 is disposed above the second lower connecting rod 41.

[0042] In this embodiment, the driven translation member body 43 is located at the outer end of the second Z-shaped translation member and is connected to the corresponding locking assembly. The second upper connecting rod 42 extends from the driven translation member body 43 toward the center of the folding chair, and the second lower connecting rod 41 extends from the second longitudinal connecting rod 44 toward the center but is positioned lower than the second upper connecting rod 42. The second longitudinal connecting rod 44 connects the second upper connecting rod 42 and the second lower connecting rod 41. The third rack 411 is disposed above the second lower connecting rod 41 and meshes with the bottom of the transmission gear 6. When the transmission gear 6 rotates, the third rack 411 drives the second lower connecting rod 41 to translate, which in turn drives the second upper connecting rod 42 and the driven translation member body 43 to translate synchronously through the second longitudinal connecting rod 44, thereby driving the driven locking assembly.

[0043] As a preferred option and not a limitation, both the first and second Z-shaped translation components in this embodiment are integrally formed, and their structures are identical to reduce manufacturing costs. Furthermore, the second Z-shaped translation component is structurally symmetrical to the first Z-shaped translation component about the central axis of the transmission gear 6 of the folding chair, and the central axis of the transmission gear 6 is located on the left and right symmetrical center planes of the chair back. That is, when the first Z-shaped translation component is on the right side, the second Z-shaped translation component is on the left side. This symmetrical arrangement ensures that the transmission path lengths on both sides are consistent and the force is evenly distributed, helping to guarantee the accuracy and reliability of synchronous action on both sides.

[0044] Furthermore, the chair back includes a chair back body 7 located at the top and a sub-plate 8 near the seat. The sub-plate 8 includes a sub-plate housing. The locking assembly and the transmission assembly are slidably disposed within the sub-plate housing. The sub-plate housing has an upper inner wall surface and a lower inner wall surface. The upper end surfaces of the first upper connecting rod 32 and the second upper connecting rod 42 abut against the upper inner wall surface of the sub-plate housing, and the lower end surfaces of the first lower connecting rod 31 and the second lower connecting rod 41 abut against the lower inner wall surface of the sub-plate housing. The sub-plate housing includes an operating port 81 for the operating member 1 to extend out, and also includes a lateral opening 82 for the positioning structure of the locking assembly to pass through.

[0045] In this embodiment, the backrest body 7 is the part that the user leans against, and the sub-plate 8 is a transition part located below the backrest body 7, adjacent to the seat, and pivotally connected to the seat. The sub-plate 8 includes a sub-plate housing, which is a hollow shell structure. The locking assembly and the transmission assembly are slidably disposed inside the sub-plate housing. The sub-plate housing serves to accommodate, protect, and guide the internal components.

[0046] The sub-plate housing includes a rear cover 83, within which are provided an upper inner wall surface and a lower inner wall surface. These two inner wall surfaces limit the internal translational components from above and below, respectively. Specifically, the upper end faces of the first upper connecting rod 32 and the second upper connecting rod 42 abut against the upper inner wall surface of the sub-plate housing, and the lower end faces of the first lower connecting rod 31 and the second lower connecting rod 41 abut against the lower inner wall surface of the sub-plate housing. In this way, the displacement of the Z-shaped translational components in the vertical direction is completely restricted by the upper and lower inner wall surfaces, ensuring that each translational component does not wobble or flip during translation, maintaining stable linear motion and helping to ensure precise meshing between the rack and gear. If the translational component deviates in the vertical direction, the meshing between the rack and gear will be affected, potentially leading to tooth disengagement or jamming. Taking the first Z-shaped translating component as an example, when the first lower connecting rod 31 is translated by the driving part 102, the first lower connecting rod 31 will also be subjected to a downward force from the driving part 102. This causes the part of the first Z-shaped translating component near the center of the seat to deflect slightly downward. At this time, on the one hand, it will put pressure on the first upper connecting rod 32 to grip the transmission gear 6 downward, making the force of the transmission gear 6 on the second Z-shaped translating component more stable and reliable. On the other hand, since the lower inner wall surface abuts against the first lower connecting rod 31, it can effectively ensure that the downward deflection of the first Z-shaped translating component near the center of the seat is not too large, avoiding the situation where the transmission is not smooth and jams due to excessive pressure between the transmission gear 6 and the first upper connecting rod 32. Therefore, the guide and limiting structure shared by the upper and lower inner walls of the sub-plate housing and the Z-shaped translating component itself is a key design to ensure transmission accuracy, smoothness and reliability.

[0047] As a preferred, but not limited, approach, surface contact is preferred between the upper inner wall surface and the upper end faces of the first upper connecting rod 32 and the second upper connecting rod 42, and between the lower inner wall surface and the lower end faces of the first lower connecting rod 31 and the second lower connecting rod 41. This increases the contact area, reduces local pressure, and limits the deflection stroke of the Z-shaped translation component, thereby reducing wear, ensuring smoothness, and extending service life. A friction-reducing layer or lubricating material can also be placed between the contact surfaces to reduce frictional resistance during translation and make operation smoother.

[0048] The sub-plate housing also has an operating port 81 and a side opening 82. The operating port 81 allows the operating component 1 to extend out of the sub-plate housing, so that the user can operate the operating component 1 from outside the housing. The side opening 82 allows the positioning structure (such as a pin) of the locking assembly to extend out of the sub-plate housing, so that the positioning structure passes through the side opening 82 and engages with a limiting structure (such as a positioning hole 10) located outside the sub-plate housing. As an optional and not limited option, the operating port 81 can be located on the top or back of the sub-plate housing, and the side opening 82 can be located on the left and right side walls of the sub-plate housing. In this embodiment, the operating port 81 is preferably located on the top of the sub-plate housing, so that the user can operate the lever from above, which is ergonomic; the side opening 82 is preferably located on the left and right side walls of the sub-plate housing, so that the pin can extend outward in a horizontal direction.

[0049] Furthermore, the positioning structure includes an elastic pin 9 and a positioning hole 10. The elastic pin 9 includes a first pin body 91 disposed on the active translation member body 33 and the driven translation member body 43, and a first elastic member 92 fixed at one end to the first pin body 91. The positioning hole 10 is located on the side plate 11 of the chair seat.

[0050] In this embodiment, the positioning structure is specifically a mating structure between the elastic pin 9 and the positioning hole 10. The first pin body 91 is a movable locking member whose movement direction is to extend and retract along the left-right direction of the folding chair (i.e., parallel to the pivot axis). The positioning hole 10 is formed on the side plate 11 of the seat, and its position corresponds to the position of the first pin body 91. When the first pin body 91 extends and inserts into the positioning hole 10, the angle of the chair back relative to the seat is fixed; when the first pin body 91 retracts and disengages from the positioning hole 10, the chair back can rotate or fold freely around the pivot. One end of the first elastic member 92 is fixed to the first pin body 91, and the other end is fixed by the top stop member 843 described below. The first elastic member 92 applies an elastic force toward the positioning hole 10 to the first pin body 91, so that when the drive part 102 engages with the teeth of the corresponding first rack 311, the first pin body 91 can remain inserted into the positioning hole 10.

[0051] The first elastic element 92 in this embodiment can be a compression spring, which has a simple and reliable structure and low cost, and is the preferred solution in this embodiment. As an optional solution and not a limitation, the first elastic element 92 can also be other forms of elastic elements such as tension springs, torsion springs, or sheet springs.

[0052] Specifically, the sub-plate housing includes a front cover 84, which includes front brackets 841 located on both sides and a rear bracket 842 located in the middle. The front brackets 841 are close to the front of the chair back, and the rear brackets 842 are close to the back of the chair back and are simultaneously abutted against the active translation member 3 and the driven translation member 4. The drive unit 102 and the transmission gear 6 are located on the back of the rear bracket 842.

[0053] In this embodiment, the front cover 84 and the rear cover 83 are the main components of the sub-plate housing, and their interiors form bracket structures for mounting and supporting various components. The front bracket 841 is located on both sides of the front cover 84 and close to the front of the chair back, while the rear bracket 842 is located in the middle of the front cover 84 and close to the back of the chair back. The rear bracket 842 is simultaneously abutted against both the active translation member 3 and the driven translation member 4, providing back support and guidance for the translational movement of the two translation members, preventing horizontal displacement or deformation of the translation members when subjected to force. The drive unit 102 and the transmission gear 6 are located on the back of the rear bracket 842, specifically on the side of the rear bracket 842 closest to the back of the chair back. This arrangement facilitates gear installation and fixation, resulting in a compact layout and a clear transmission path.

[0054] As an illustration and not a limitation, the front bracket 841 and the rear bracket 842 can be integrally formed, or they can be fixed by connectors or welding. The integral forming method is beneficial for reducing the number of parts and reducing assembly difficulty, and is the preferred solution in this embodiment.

[0055] The front end bracket 841 is also provided with a top stop 843 for fixing the other end of the first elastic member 92. The top stop 843 extends backward from the front end bracket 841 and has a through hole in the middle for the first pin body 91 to pass through.

[0056] In this embodiment, the top stop 843 is an extension structure further formed on the front support 841, extending from the front support 841 towards the back of the chair. The top stop 843 is used to fix the other end of the first elastic member 92 (one end of the first elastic member 92 is fixed to the first pin body 91), thereby forming an elastic connection between the first pin body 91 and the top stop 843. A through hole is provided in the middle of the top stop 843, through which the first pin body 91 passes, allowing the first pin body 91 to slide freely in the through hole.

[0057] As an optional rather than limiting option, the top stop 843 can be a boss structure integrally formed on the front end bracket 841, or it can be a separate component fixed to the front end bracket 841 by fasteners. In this embodiment, the top stop 843 is a block structure and is installed on the front end bracket 841 by screws.

[0058] The outer sides of the active translation component body 33 and the driven translation component body 43 are also formed with a bent portion 12, and the first pin body 91 is provided on the bent portion 12 and extends outward through the through hole. When the first elastic element 92 is in a compressed state, and the bent portion 12 is against the top stop 843, the first pin body 91 extends out of the positioning hole 10 under the tension of the first elastic element 92.

[0059] In this embodiment, the bending portion 12 is a structure formed by further bending and extending the outer ends of the active translation member body 33 and the driven translation member body 43. When the active translation member body 33 and the driven translation member body 43 are at their maximum travel on the side of the seat, the bending portion 12 abuts against the top stop 843 to limit the maximum travel of the active translation member body 33 and the driven translation member body 43 on both sides of the seat. The first pin body 91 is disposed on the bending portion 12 and moves together with the bending portion 12. The design of the bending portion 12 allows the position of the first pin body 91 to be offset towards the center of the sub-plate 8, so that the first pin body 91 is aligned with the through hole in the middle of the top stop 843 and the positioning hole 10 on the side plate 11 of the seat in the pivot axis direction (i.e., the left-right direction of the folding chair), which facilitates the extension and retraction of the pin in this direction and accurate insertion into the positioning hole 10.

[0060] In this embodiment, the first elastic element 92 is always in a compressed state after assembly, that is, the first elastic element 92 always applies an outward elastic force to the first pin body 91. When the bent portion 12 abuts against the top stop member 843, the first pin body 91 just extends out of the positioning hole 10.

[0061] In one embodiment of the present invention, based on the shortcomings of existing folding chairs in terms of inconvenient operation and insufficient reliability in adjusting the height of the chair legs, the present invention makes the following improvements: Specifically, the folding chair also includes chair legs, which include fixed leg tubes 13 and telescopic inner tubes 14, with the telescopic inner tubes 14 telescopically fitted inside the fixed leg tubes 13. The fixed leg tube 13 is provided with a locking component, which includes a pressing part 131, an L-shaped linkage member 132 that is linked with the pressing part 131, and a locking pin 133 provided on the L-shaped linkage member 132. The telescopic inner tube 14 is provided with a plurality of adjustable locking holes 141 spaced apart along its length; The fixed leg tube 13 is provided with a leg tube housing 136 with a reset cavity. The L-shaped linkage 132 is disposed in the reset cavity. The first arm of the L-shaped linkage 132 is abutted against the outer wall of the telescopic inner tube 14. The second arm of the L-shaped linkage 132 is provided with the locking pin 133. The locking assembly also includes a reset spring 134 disposed between the inner wall of the reset cavity and the second arm of the L-shaped linkage 132. The fixed leg tube 13 is provided with a clearance hole 135 at the corresponding position of the pressing part 131 on its surface. The locking pin 133 passes through the fixed leg tube 13 and is inserted into the corresponding adjustment lock hole 141 on the telescopic inner tube 14 under the action of the return spring 134. When the pressing part 131 is pressed, the L-shaped linkage 132 drives the locking pin 133 to exit the adjustment lock hole 141.

[0062] In this embodiment, the chair legs adopt a telescopic structure in which a fixed leg tube 13 and a telescopic inner tube 14 are sleeved together. The telescopic inner tube 14 is slidably disposed inside the sleeve 137 of the fixed leg tube 13. The sleeve 137 has a notch 1371 on its side corresponding to the first arm of the L-shaped linkage 132. The user can adjust the total length of the chair legs by changing the length of the telescopic inner tube 14 extending out of the fixed leg tube 13, thereby adjusting the height of the chair seat from the ground. The telescopic inner tube 14 has multiple adjustment locking holes 141 spaced apart along its length. Different adjustment locking holes 141 correspond to different extension lengths—the closer the adjustment locking hole 141 is to the upper end of the telescopic inner tube 14, the longer the chair leg extension length and the higher the chair seat height; the closer the adjustment locking hole 141 is to the lower end of the telescopic inner tube 14, the shorter the chair leg extension length and the lower the chair seat height. As an optional rather than a limitation, the spacing between adjacent adjustable lock holes 141 can be from 10mm to 30mm. The specific value can be set according to the height adjustment requirements of different usage scenarios. For example, outdoor hairdressing scenarios require higher height accuracy, so a smaller spacing (such as 10mm) can be used. At the same time, different chair leg heights can be adjusted to adapt to uneven outdoor surfaces and other requirements.

[0063] The locking component is located on the fixed leg tube 13. Its core function is to fix the telescopic inner tube 14 to a certain extension length in the locked state, and to allow the telescopic inner tube 14 to slide freely in the unlocked state. The pressing part 131 is a component that is directly operated by the user. It extends from the clearance hole 135 on the surface of the fixed leg tube 13 and protrudes from the surface of the fixed leg tube 13, making it easy for the user to press with their fingers.

[0064] The L-shaped linkage 132 is disposed in the reset cavity inside the fixed leg tube 13 and can slide within the reset cavity during pressing operations. The L-shaped linkage 132 includes a first arm and a second arm that are perpendicular to each other. A locking pin 133 disposed on the second arm passes through the fixed leg tube 13 and inserts into the corresponding adjusting locking hole 141 on the telescopic inner tube 14 in the locked state, thereby restricting the axial movement of the telescopic inner tube 14 relative to the fixed leg tube 13. A reset spring 134 is disposed between the inner wall of the reset cavity and the second arm of the L-shaped linkage 132, and always applies an elastic force to the L-shaped linkage 132 toward the locking position.

[0065] When the user needs to adjust the height of the chair legs, they can press the pressing part 131. The pressing part 131 drives the L-shaped linkage 132 to move within the reset cavity. The L-shaped linkage 132 drives the locking pin 133 to disengage from the adjustment lock hole 141 of the telescopic inner tube 14, allowing the telescopic inner tube 14 to extend and retract freely. After adjusting to the desired length, the pressing part 131 is released. The reset spring 134 drives the L-shaped linkage 132 to reset, and the locking pin 133 re-passes through the fixed leg tube 13 and inserts into the corresponding adjustment lock hole 141 on the telescopic inner tube 14, relocking the length of the telescopic inner tube 14.

[0066] In this embodiment, the first arm of the L-shaped linkage 132 is abutted against the outer wall of the telescopic inner tube 14. After the locking pin 133 exits the adjustment lock hole 141, the first arm provides a certain guiding and supporting effect on the outer wall of the telescopic inner tube 14, so that the telescopic inner tube 14 remains stable and does not wobble during the telescopic process, ensuring the smoothness of the telescopic action.

[0067] Compared to existing technologies where the pin is easily lost, the spring latch is easily accidentally unlocked, and single-point locking causes the chair legs to wobble, the locking assembly in this embodiment integrates the pressing part 131, the L-shaped linkage 132, the locking pin 133, and the return spring 134 inside the fixed leg tube 13. The overall structure is compact and stable, with no exposed vulnerable parts. Under the action of the return spring 134, the locking pin 133 always remains inserted into the adjustment lock hole 141, realizing a constant lock function. Users only need to press the pressing part 131 with one hand to complete the chair leg height adjustment operation, and it automatically locks when released, taking into account both the convenience of operation and the reliability of locking.

[0068] While existing folding chairs can achieve multiple functions by adding external attachments, the connection structure between the attachments and the chair body usually only applies to the unfolded state. When the folding chair needs to be folded for storage or moved, the user must remove the attachments from the chair body and carry them separately. Otherwise, the folded attachments will take up extra space or even hinder the folding action due to misalignment. This not only increases the disassembly and assembly steps before and after use but also easily leads to the loss of the attachments during separate storage and transportation. For scenarios requiring frequent relocation, such as outdoor hairdressing or mobile services, the need to disassemble and assemble the attachments every time the stall is set up and closed severely impacts work efficiency and user experience.

[0069] In view of the shortcomings of existing folding chairs, such as inconvenience in storing accessories and the easy loss of accessories, the present invention makes the following improvements: Specifically, the folding chair also includes an external attachment, which is a shelf 18 or a footrest 16. The external attachment is provided with an insert body 15, and the insert body 15 has a first insertion port 151 and a second insertion port 152. The opening of the first socket 151 faces a first direction, and the opening of the second socket 152 faces a second direction, with the first direction and the second direction being perpendicular to each other. When the folding chair is in the unfolded state, the external attachment is secured to the folding chair in the vertical direction through the first insertion port 151. When the folding chair is in the folded state, the external attachment is secured to the folding chair via the second socket 152.

[0070] In this embodiment, the external attachment and the insert body 15 are preferably integrally formed, which can be directly installed on the folding chair without the need for intermediate adapters, reducing the number of parts and avoiding the risk of losing the adapters.

[0071] The first connector 151 and the second connector 152 correspond to the unfolded and folded states of the folding chair, respectively. When the folding chair is unfolded, the external attachment is secured vertically to the folding chair via the first connector 151, extending outwards to the usage position. The shelf 18 remains horizontal to support tools, and the footrest 16 remains horizontal to rest the feet. When the folding chair is folded, the external attachment switches to the second connector 152. Since the opening direction of the second connector 152 is perpendicular to the first connector 151, the installation posture of the external attachment changes accordingly, becoming close to the chair body and maintaining the same shape as the folded chair, without taking up extra space.

[0072] As a preferred embodiment and not a limitation, taking the footrest 16 of this embodiment as an example, the footrest 16 of this embodiment includes a footrest body 161, extension rods 162 located on both sides of the rear of the footrest body 161, and connecting arms 163 connected to the free ends of the extension rods 162. The extension rods 162 include horizontal segments and vertical segments. The vertical segments form insert bodies 15. The first insertion port 151 is located behind the top of the vertical segment and is parallel to the vertical segment and faces the footrest body 161. The second insertion port 152 is located in front of the bottom of the vertical segment and is perpendicular to the vertical segment and faces the footrest body 161.

[0073] Compared to the shortcomings of existing technologies where external attachments need to be disassembled and carried separately when folded and stored, which is cumbersome and easy to lose, this embodiment sets two perpendicular openings on the external attachment, so that the external attachment can be connected to the folding chair in different postures in both unfolded and folded states, which greatly shortens the time for setting up and closing the stall, and effectively reduces the risk of losing the external attachment.

[0074] As a preferred embodiment and not a limitation, the folding chair in this embodiment also includes casters 17 disposed on the outer side of the sub-plate 8. For example, the casters 17 can be disposed on the side plate 11 of the seat. Please refer to... Figure 11 As shown, when the folding chair is in the folding state, the folding of the folding chair is centered on the pivot between the seat and the backrest (located at the junction of the two). Since the pulley is located on the outer side of the sub-board 8 near the pivot, the pulley 17 is located at the bottom of the folding chair after folding, which makes it easier for the user to pull the folding chair and improves the portability of the folding chair.

[0075] In one implementation of the present invention, based on the shortcomings of existing folding chair headrest height adjustment mechanisms, such as loose structure, inconvenient operation, and insufficient locking reliability, the present invention makes the following improvements: Specifically, the folding chair in this embodiment also includes a height adjustment rod 19 connected to the bottom of the headrest and an adjustment latch assembly 20 fixed to the back of the chair back body 7. The height adjustment rod has several adjustment holes (conventional structure, not shown in the figure) in the length direction. The adjustment latch assembly includes a latch outer shell 21, a latch inner shell 22, and a latching member 23 disposed between the latch outer shell and the latch inner shell. The inner housing 22 of the latch includes a first facade 221 and a second facade 222 disposed opposite to each other, and a connecting surface 223 located between the first facade 221 and the second facade 222, such that the cross-section of the inner housing 22 of the latch is U-shaped. The encirclement of the U-shaped inner housing 22 forms a first longitudinal channel 224 through which the height adjustment rod 19 passes. The inner housing 22 of the latch also includes a transverse clearance notch 225 provided on the connecting surface 223 and connected to the first longitudinal channel 224. The latch member 23 is slidably disposed in the transverse clearance notch 225, and the inner wall surface of the transverse clearance notch 225 is adapted to the outer contour of the latch member 23 to guide and limit the translational direction of the latch member 23. A pin hole 226 is formed on the first facade 221. The locking member 23 includes an L-shaped locking member body, which includes a third arm 231 corresponding to the lateral clearance notch 225 and a fourth arm 232 corresponding to the first vertical surface 221 of the inner housing 22. It also includes a push switch 233 fixedly disposed at the free end of the third arm 231 and a second elastic member 234 disposed between the push switch 233 and the second vertical surface 222 of the inner housing 22. The second elastic member 234 is in a compressed state, constantly applying an elastic force to the locking member 23 to cause the pin 235 to tend to insert into the adjustment hole. A pin 235 is fixedly disposed on the fourth arm 232. The pin 235 passes through a pin hole 226 on the first vertical surface 221 and is used to cooperate with the adjustment hole on the height adjustment rod 19, so that the pillow can be movably fixed at the corresponding height. The outer casing 21 of the latch includes a transverse outer protective plate 211 that is connected and fixed to the inner casing 22 of the latch, a surrounding plate that is disposed on one side of the transverse outer protective plate 211 and corresponds to the fourth arm 232 of the latch 23, and a guide plate that is disposed on the other side of the transverse outer protective plate 211 and corresponds to the push switch 233. The enclosure includes a pair of first parallel guide plates 212 and a baffle 213 connected between the two first parallel guide plates 212. The baffle 213 is used to limit the lateral displacement of the fourth arm 232 of the locking member 23. The guide plate includes a pair of second parallel guide plates 214, and the push switch 233 is movably disposed between the two second parallel guide plates 214; A second longitudinal channel 215 is formed between the first parallel guide plate 212 and the second parallel guide plate 214 for mounting the inner housing 22 of the latch.

[0076] Please refer to Figure 13 and Figure 14 When the adjusting latch assembly 20 is pressed, the pressing switch 233 drives the latch 23 under the user's pressing force. The latch 23, limited by the lateral clearance notch 225 between the latch outer shell 21 and the latch inner shell 22, moves to the left as a whole. The second elastic element 234 is compressed, and simultaneously, the pin 235 disengages from the adjustment hole of the height adjustment rod 19, completing the unlocking operation of the adjusting latch assembly 20 on the height adjustment rod 19. After the user adjusts the height by pulling out the headrest, stopping the pressing switch 233 causes the latch 23 to move to the right under the restoring force of the second elastic element 234, and the pin 235 re-inserts into the corresponding height adjustment hole on the height adjustment rod 19, completing the locking of the headrest height.

[0077] Compared to the shortcomings of existing headrest height adjustment mechanisms, such as loose structure, inconvenient operation, and insufficient locking reliability, this embodiment integrates the inner housing 22, the locking element 23, and the outer housing 21 into a single adjustable locking assembly 20. Positioning of the components is achieved through guiding and limiting mechanisms, eliminating the need for complex positioning fixtures or additional external covers. This reduces the complexity of injection molding or stamping dies, lowers manufacturing costs, and reduces assembly time. Users can adjust the height simply by pressing the push switch 233 with one hand and pulling the headrest with the other; releasing the switch automatically locks the headrest. No additional tools are required, making operation simple and intuitive. Simultaneously, the second elastic element 234 remains compressed, ensuring the pin 235 remains inserted into the adjustment hole in its natural state, achieving a constant locking function for the headrest height. Furthermore, the independently designed push switch prevents accidental unlocking when the head presses against the headrest, effectively preventing accidental slippage or loosening during use and ensuring safety.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A folding chair, comprising a seat, a backrest, and a pivot connecting the seat and the backrest, characterized in that, Also includes: Two locking components are symmetrically arranged on the left and right sides of the folding chair. Each locking component includes a limiting structure on one of the seat and the backrest, and a positioning structure on the other. The positioning structure is used to cooperate with the limiting structure so that the backrest is rotatably fixed at at least a predetermined angle relative to the seat. A transmission assembly, disposed on the chair back, includes an operating component and a linkage transmission component; The operating component is movably mounted on the chair back and includes an operating part for user operation and a drive part connected to the linkage transmission component. The linkage transmission component is slidably mounted on the chair back, and its two ends are respectively connected to the two locking components; When the operating component moves, it drives the linkage transmission component to translate through the driving part. The translation of the linkage transmission component causes the two locking components to move synchronously, so that the two positioning structures and the corresponding limiting structures can engage or disengage at the same time.

2. The folding chair according to claim 1, characterized in that, The linkage transmission component includes an active translation component on one side, a driven translation component on the other side, and a transmission component connecting the active translation component and the driven translation component. The transmission component is used to drive the driven translation component so that the driven translation component moves away from or closer to the active translation component synchronously.

3. The folding chair according to claim 2, characterized in that, The active translation component is provided with a first rack, and the driving part of the operating component is an active gear that meshes with the first rack.

4. The folding chair according to claim 3, characterized in that, The linkage transmission component includes a transmission gear, the active translation component further includes a second rack, and the driven translation component is provided with a third rack; the second rack meshes with one side of the transmission gear, and the third rack meshes with the other side of the transmission gear.

5. The folding chair according to claim 4, characterized in that, The active translation component is a first Z-shaped translation component. The first Z-shaped translation component includes an active translation component body connected to a side locking component, a first lower connecting rod extending from the active translation component body towards the center, a first upper connecting rod connected to the transmission component, and a first longitudinal connecting rod connecting the first lower connecting rod and the first upper connecting rod. The first rack is provided above the first lower connecting rod, and the second rack is provided below the first upper connecting rod. The lower side of the drive gear meshes with the first rack of the first lower connecting rod; The upper side of the transmission gear meshes with the second rack of the first upper connecting rod; The driven translation member includes a driven translation member body connected to a locking assembly on the other side, and a third rack that meshes with the bottom of the transmission gear.

6. The folding chair according to claim 5, characterized in that, The driven translation member is a second Z-shaped translation member, which includes a driven translation member body connected to the locking assembly on the other side, a second upper connecting rod extending from the driven translation member body towards the center, a second lower connecting rod connected to the transmission member, and a second longitudinal connecting rod connecting the second upper connecting rod and the second lower connecting rod; the third rack is disposed above the second lower connecting rod.

7. The folding chair according to claim 6, characterized in that, The chair back includes a chair back body located at the top and a sub-plate near the seat. The sub-plate includes a sub-plate housing. The locking assembly and the transmission assembly are slidably disposed in the sub-plate housing. The sub-plate housing has an upper inner wall surface and a lower inner wall surface. The upper end surfaces of the first upper connecting rod and the second upper connecting rod abut against the upper inner wall surface of the sub-plate housing, and the lower end surfaces of the first lower connecting rod and the second lower connecting rod abut against the lower inner wall surface of the sub-plate housing. The sub-plate housing includes an operating port for the operating element to extend out, and a lateral opening for the positioning structure of the locking assembly to pass through.

8. The folding chair according to claim 7, characterized in that, The positioning structure includes an elastic pin and a positioning hole. The elastic pin includes a first pin body disposed on the active translation member body and the driven translation member body, and a first elastic member with one end fixed to the first pin body. The positioning hole is located on the side plate of the chair seat. The sub-plate housing includes a front cover, which includes front support brackets located on both sides and a rear support bracket located in the middle. The front support brackets are close to the front of the chair back, and the rear support brackets are close to the back of the chair back and are simultaneously abutted against the active translation component and the driven translation component. The active gear and the transmission gear are located on the back of the rear support bracket. The front end bracket is also provided with a top stop for fixing the other end of the first elastic member. The top stop extends backward from the front end bracket and has a through hole in the middle for the first pin body to pass through. The outer sides of the active translation component body and the driven translation component body are also formed with bent portions, and the first pin body is disposed in the bent portion and extends outward through the through hole. When the first elastic element is in a compressed state, and the bent portion is against the top stop, the first pin body extends out of the positioning hole under the tension of the first elastic element.

9. The folding chair according to any one of claims 1 to 8, characterized in that, It also includes chair legs, which include fixed leg tubes and telescopic inner tubes, wherein the telescopic inner tubes are telescopically fitted inside the fixed leg tubes; The fixed leg tube is provided with a locking assembly, which includes a pressing part, an L-shaped linkage member linked with the pressing part, and a locking pin provided on the L-shaped linkage member. The telescopic inner tube is provided with multiple adjustable locking holes spaced apart along its length. The fixed leg tube is provided with a leg tube housing with a reset cavity. The L-shaped linkage is disposed in the reset cavity. The first arm of the L-shaped linkage is abutted against the outer wall of the telescopic inner tube. The second arm of the L-shaped linkage is provided with the locking pin. The locking assembly also includes a reset spring disposed between the inner wall of the reset cavity and the second arm of the L-shaped linkage. The fixed leg tube surface is provided with a clearance hole at the corresponding position of the pressing part. The locking pin passes through the fixed leg tube and is inserted into the corresponding adjustment lock hole on the telescopic inner tube under the action of the return spring. When the pressing part is pressed, the L-shaped linkage drives the locking pin to exit the adjustment lock hole.

10. The folding chair according to any one of claims 1 to 8, characterized in that, It also includes an external attachment, which is a shelf or footrest. The external attachment has a insert body, and the insert body has a first socket and a second socket. The opening of the first socket faces a first direction, and the opening of the second socket faces a second direction, wherein the first direction and the second direction are perpendicular to each other; When the folding chair is in the unfolded state, the external attachment is secured to the folding chair vertically through the first socket; When the folding chair is in the folded state, the external attachment is secured to the folding chair via the second connector.

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