Chair backrest assembly and chair

Abstract

To provide a backrest assembly capable of improving comfort when a user uses a chair.SOLUTION: The chair back assembly 100 includes a back frame 110 connected to a chair base 200, a back body 120 disposed on one side of the back frame, a first transmission unit 130 disposed between the back frame and the back body and in transmission connection with the back body, and a second transmission unit 140 disposed between the back frame and the back body and spaced apart from the first transmission unit in a longitudinal direction of the back frame. And a second transmission assembly 140 in transmission connection with the backrest body, wherein the first transmission assembly is slidably connected to the backrest frame, and the second transmission assembly is rotatably connected to the backrest frame, so that the backrest body can move relative to the backrest frame when the backrest assembly is subjected to an external force.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This application relates to the technical field of chairs, and more particularly to chair back assemblies and chairs. [Background technology]

[0002] Chairs that can meet the needs of people sitting to work, study, or rest are widely seen in places such as offices and study rooms. Chairs are usually composed of multiple parts, such as a seat, a backrest, armrests, and a headrest. Here, the backrest is a component that supports the back of the human body, maintaining the user's sitting posture and relieving pressure on the neck, back, and lumbar area. In the related art, when the user's sitting posture changes, it is difficult for the chair back to be adaptively adjusted according to the change in the user's sitting posture, which results in a problem of reduced comfort when the user uses the chair. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THE INVENTION The primary object of the present application is to provide a chair back assembly that provides improved comfort to the user when using the chair. [Means for solving the problem]

[0004] In order to achieve the above object, the present application proposes a chair back assembly comprising: a back frame connected to the base of the chair; a back body provided on one side of the back frame; a first transmission unit provided between the back frame and the back body and transmission-connected to the back body; and a second transmission unit provided between the back frame and the back body, spaced apart from the first transmission unit along the longitudinal direction of the back frame, and transmission-connected to the back body, wherein the first transmission unit is slidably connected to the back frame and the second transmission unit is rotatably connected to the back frame so that the back body can move relative to the back frame when the back assembly is subjected to an external force.

[0005] In some embodiments, the first transmission unit includes a sliding member slidably mounted on the backrest frame and transmission-coupled with the backrest body.

[0006] In some embodiments, the back frame is provided with a sliding cavity extending in a longitudinal direction, and the sliding member is inserted into and slidingly engaged with the sliding cavity.

[0007] In some embodiments, at least one of the back frame and the sliding member is provided with a sliding structure, which supports the sliding member to slide along the sliding cavity.

[0008] In some embodiments, the sliding structure includes at least one support member pivotally mounted on one of the back frame and the sliding member and in rolling contact with the other of the back frame and the sliding member.

[0009] In some embodiments, the first transmission unit further includes a first support member rotatably connected to the sliding member, and the sliding member is transmission-connected to the backrest body via the first support member.

[0010] In some embodiments, the first transmission unit further includes at least two sets of second support members respectively provided on opposite sides of the first support member, each set of the second support members including at least one second support member movably connected to the first support member, and the first support member is movably connected to the backrest body via at least two sets of the second support members.

[0011] In some embodiments, a first accommodating cavity is provided in one of the backrest body and the second support member, and a first engaging member is provided in the other, and the first engaging member is accommodated in the first accommodating cavity so that the second support member and the backrest body are movably connected.

[0012] In some embodiments, the second transmission unit includes a rotating member having one end rotatably connected to the backrest frame and the other end transmission-connected to the backrest body.

[0013] In some embodiments, the second transmission unit further includes a third support member rotatably connected to the rotating member, and the rotating member is transmission-connected to the backrest body via the third support member.

[0014] In some embodiments, the second transmission unit further includes at least two sets of fourth support members respectively provided on opposite sides of the third support member, each set of the fourth support members including at least one fourth support member movably connected to the third support member, and the third support member is movably connected to the backrest body via at least two sets of the fourth support members.

[0015] In some embodiments, a second accommodating cavity is provided in one of the backrest body and the fourth support member, and a second engaging member is provided in the other, and the second engaging member is accommodated in the second accommodating cavity so that the fourth support member and the backrest body are movably connected.

[0016] In some embodiments, the device further comprises a first linkage member having one end hingedly connected to the first transmission unit and the other end hingedly connected to the second transmission unit.

[0017] In some embodiments, the chair further comprises a second linkage member having one end hinged to the second transmission unit and another end hinged to the chair base.

[0018] In some embodiments, the backrest body is provided with a plurality of openings, the plurality of openings being located on the lateral sides of the backrest body, and each of the openings extending from the edge of one side on which it is located toward the other side.

[0019] In some embodiments, the backrest body includes a plurality of support ribs spaced apart along the longitudinal direction of the backrest body, and the gap between any two adjacent support ribs defines the opening.

[0020] The present application further proposes a chair comprising a base and the back assembly, wherein the back frame is connected to the base. [Effects of the Invention]

[0021] In the chair back assembly according to the present application, the sliding connection design of the first transmission unit and the pivoting connection design of the second transmission unit allow the back main body to move relative to the back frame. When the back assembly is subjected to an external force (e.g., a force exerted on the back assembly when a person leans against the back assembly and leans back), the back main body can move relative to the back frame. For example, when a user leans back, the back main body follows the user's back and / or lumbar, thereby adapting to changes in the user's sitting posture and providing more comfortable support to the user, improving the user's comfort when using the chair. [Brief explanation of the drawings]

[0022] [Figure 1]1 is a structural schematic diagram of a chair according to an embodiment of the present invention; [Figure 2] 1 is a structural schematic diagram of a portion of a chair back assembly according to an embodiment of the present application; [Figure 3] FIG. 2 is a structural schematic diagram of another portion of the chair back assembly according to an embodiment of the present application. [Figure 4] FIG. 10 is a structural schematic diagram of yet another portion of a chair back assembly according to an embodiment of the present application. [Figure 5] FIG. 10 is an exploded view of yet another portion of a chair back assembly in accordance with one embodiment of the present disclosure. [Figure 6] FIG. 10 is a structural schematic diagram of yet another portion of a chair back assembly according to an embodiment of the present application. [Figure 7] FIG. 7 is an enlarged view of part A in FIG. 6. [Figure 8] 3 is a schematic diagram of a connection structure between a first support member and a second support member in one embodiment of the present application. FIG. [Figure 9] FIG. 3 is a structural schematic diagram of a second support member in one embodiment of the present application. [Figure 10] FIG. 10 is a structural schematic diagram of a fourth support member in one embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. Based on the embodiments of the present application, all other embodiments that can be obtained by those skilled in the art without any creative efforts fall within the scope of protection of the present application.

[0024] Note that all directional indications (e.g., up, down, left, right, front, back, etc.) in the embodiments of the present application are used only to interpret the relative positional relationships, movement situations, etc. between components in a specific posture (the posture shown in the drawings). When the specific posture changes, the directional indications also change accordingly.

[0025] When a part is said to be "fixed" or "mounted" to another part, the part may be directly fixed or mounted to the other part, or may be fixed or mounted to the other part via an intermediate part. When a part is said to be "connected" to another part, the part may be directly connected to the other part, or may be connected via an intermediate part.

[0026] Furthermore, the terms "first," "second," etc., used herein are for descriptive purposes only and do not indicate or imply the relative importance of, or the number of, the designated technical features. Therefore, a feature defined by "first" or "second" may explicitly or implicitly include at least one of the designated feature. Furthermore, the technical solutions in each embodiment may be combined with each other, provided that such combinations are feasible by a person skilled in the art. If a combination of technical solutions results in a contradiction or is impossible to realize, such combination shall be deemed non-existent and shall not be included in the scope of the claims of this application.

[0027] Chairs are pieces of furniture that people sit on when working, studying or resting, and their technology is developing in a more humanized and intelligent direction, aiming to provide users with a comfortable and healthy posture experience.

[0028] Generally, a chair is mainly composed of a base, seat, backrest, and other structures. The base (also called a chassis) serves as the foundation of the entire chair structure, bearing the weight of the human body and various pressures that may occur during use, and provides sufficient strength and stability. The base is also an important component that connects the chair body (e.g., the backrest, seat, etc.). Each component is combined using a specific connection method, such as a fixed connection or a pivotal connection, to form a complete chair structure. The seat is mounted on the base, and the backrest is mounted above and behind the seat. When a person sits on the chair, they sit on the seat, which supports their buttocks and thighs. The back and / or lower back can lean against the backrest, which supports the back and / or lower back of the person.

[0029] An embodiment of the present application provides a chair back assembly 100. As shown in Fig. 1, the chair back assembly 100 includes a back frame 110 connected to a chair base 200, a back body 120 provided on one side of the back frame 110, a first transmission unit 130 provided between the back frame 110 and the back body 120 and transmission-connected to the back body 120, and a second transmission unit 130 provided between the back frame 110 and the back body 120 and transmission-connected to the first transmission unit 130. and a second transmission unit 140 arranged at intervals along the longitudinal direction of the backrest frame 110 and transmission-connected to the backrest main body 120, wherein the first transmission unit 130 is slidably connected to the backrest frame 110 and the second transmission unit 140 is rotatably connected to the backrest frame 110 so that the backrest main body 120 can move relative to the backrest frame 110 when an external force is applied to the backrest assembly 100.

[0030] The backrest frame 110 is located behind the base 200 and is connected to the base 200. It cooperates with the backrest main body 120 to support the back and / or lumbar of the human body. The connection between the backrest frame 110 and the base 200 can be fixed or pivoted, but is not limited thereto. The backrest frame 110 has a generally rod-like outer structure extending along the longitudinal direction of the chair. Its shape can be various, such as an arc, an S-shape, or an L-shape, and can be set according to actual structural needs. To ensure sufficient support strength, the backrest frame 110 can be made of metal (e.g., steel, aluminum alloy, etc.), plastic, or other materials. The backrest frame 110 includes a backrest support part 111 that supports the backrest main body 120 and a base connection part 112 that is pivotally connected to the base 200. Here, the pivotal connection structure between the backrest frame 110 and the base 200 can be provided such that the base connecting portion 112 of the backrest frame 110 is penetrated into the base 200 by a hinge axis Jz, thereby being pivotally connected to the base 200. Furthermore, a rotational member 113 may be fixedly connected to the base connecting portion 112 of the backrest frame 110, and the rotational member 113 may be fitted onto the hinge axis Jz, thereby forming a pivotable connection relationship with the base 200. This is merely an example and is not limiting.

[0031] The backrest body 120, as the core support structure of the backrest assembly 100, is made of nylon, metal, high-strength plastic, or the like, and provides the strength and rigidity necessary to support the back and / or lumbar region of the human body. The backrest body 120 may be provided with a padding layer and covered with an outer skin. The main function of the padding layer is to provide comfortable support and cushioning, and materials such as sponge, foam plastic, memory foam, and the like may be selected. The outer skin protects the padding layer and improves aesthetics, and may be made of fabric, leather, synthetic leather, and the like, and may be selected according to actual needs and is not limited here.

[0032] The backrest body 120 may have a single body structure, i.e., the number of bodies is one. The backrest body 120 may be provided corresponding to a human body part, and may support only the back of the human body, only the lumbar region of the human body, or both the back and lumbar region of the human body. Alternatively, the backrest body 120 may have a multi-body structure, i.e., a multi-body structure, i.e., a multi-body structure with more than one body. For example, if the backrest body 120 has a double body structure, specifically, the backrest body 120 has a first backrest body and a second backrest body, which are arranged in order along the longitudinal direction of the chair, with the first backrest body supporting the back of the human body and the second backrest body supporting the lumbar region of the human body. Alternatively, the first backrest body and the second backrest body may be arranged in order along the transverse direction of the chair. This is merely an example and is not limiting.

[0033] 1 , the first transmission unit 130 and the second transmission unit 140 are vertically spaced apart along the longitudinal direction of the backrest frame 110. The first transmission unit 130 is slidably connected to the backrest frame 110 and is transmission-connected to the backrest main body 120, so that the backrest main body 120 can slide relative to the backrest frame 110 via the first transmission unit 130. The first transmission unit 130 may have various structural configurations as long as they can support the backrest main body 120 so that it can slide relative to the backrest frame 110. Specific examples will be described in the following embodiments. The second transmission unit 140 is rotatably connected to the backrest frame 110 and is transmission-connected to the backrest main body 120, so that the backrest main body 120 can rotate relative to the backrest frame 110 via the second transmission unit 140. The second transmission unit 140 may have a variety of structural configurations as long as it can rotatably support the backrest main body 120 relative to the backrest frame 110, and specific examples will be described in further embodiments below. The transmission connection between the first transmission unit 130, the second transmission unit 140, and the backrest main body 120 may be a fixed connection or a movable connection, and is not limited in this embodiment as long as power transmission is achieved between the first transmission unit 130, the second transmission unit 140, and the backrest main body 120. The movement of the backrest main body 120 relative to the backrest frame 110 specifically includes sliding the backrest main body 120 relative to the backrest frame 110 via the first transmission unit 130, and simultaneously rotating the backrest main body 120 relative to the backrest frame 110 via the second transmission unit 140, thereby changing the angle and / or position.

[0034] When the backrest assembly 100 is subjected to an external force, the backrest main body 120 may move relative to the backrest frame 110. Even if the user applies a force to the backrest main body 120, but the force is insufficient to rotate the backrest frame 110 relative to the base 200, or the backrest frame 110 cannot rotate relative to the base 200, the backrest main body 120 can still move relative to the backrest frame 110 (the range of movement is relatively small), thereby realizing self-adaptive adjustment.

[0035] Alternatively, if the user applies force to the backrest main body 120 or the backrest frame 110, and the backrest frame 110 can rotate relative to the base 200, and the force can rotate the backrest frame 110 relative to the base 200, then by transmitting force to the backrest main body 120, the backrest main body 120 can move relative to the backrest frame 110 (the range of movement is relatively large), thereby realizing self-adaptive adjustment.

[0036] Specifically, when a force is applied to the backrest main body 120, the backrest main body 120 slides self-adaptively on the backrest frame 110 by the first transmission unit 130, and rotates self-adaptively by the second transmission unit 140. Furthermore, when a force is applied to the backrest main body 120 or the backrest frame 110 to rotate the backrest frame 110, the first transmission unit 130 and the second transmission unit 140 are operated, and at the same time, the backrest main body 120 adjusts its angle and / or position self-adaptively.

[0037] In this embodiment, the chair back assembly 100 has a sliding connection design for the first transmission unit 130 and a pivoting connection design for the second transmission unit 140, allowing the back main body 120 to move relative to the back frame 110. When an external force (e.g., a force exerted on the back assembly 100 when a human body leans against the back assembly 100 and leans back) is applied to the back assembly 100, the back main body 120 can move relative to the back frame 110. For example, when a user leans back, the back main body 120 follows the user's back and / or lumbar region, thereby adapting to changes in the user's sitting posture and providing more comfortable support to the user, thereby improving the user's comfort when using the chair.

[0038] 1 and 2, in some embodiments, the first transmission unit 130 includes a sliding member 131 slidably mounted on the backrest frame 110 and transmission-coupled with the backrest main body 120. The sliding member 131 is attached to the backrest frame 110 and is slidable on the backrest frame 110. Specifically, the sliding member 131 may have the structural form of, for example, a sliding rod, a sliding cylinder, a slider base, a sliding frame, or a sliding rail, and forms a sliding relationship with the backrest frame 110 to achieve sliding installation on the backrest frame 110. In the backrest frame 110, the sliding member 131 is mounted on the upper part of the backrest frame 110 to correspond to the upper half of the backrest main body 120 (which can also be regarded as the part of the backrest main body 120 that supports the back of the human body). The backrest main body 120 and the sliding member 131 are transmission-coupled. The backrest body 120 can slide relative to the backrest frame 110 by means of the provided slide member 131 , and the slide member 131 supports the sliding of the backrest body 120 on the backrest frame 110 .

[0039] The power source for the sliding of the sliding member 131 is as follows. First, when a user leans back against the backrest main body 120, the force acting on the backrest main body 120 increases as the user leans back. The force acting on the backrest main body 120 acts simultaneously on the sliding member 131 and the backrest frame 110, causing the backrest frame 110 to rotate backward correspondingly, and the sliding member 131 to slide on the backrest frame 110, thereby supporting the sliding of the backrest main body 120 relative to the backrest frame 110. Secondly, it is based on disposing an interlocking mechanism on the sliding member 131. The interlocking mechanism is connected between the sliding member 131 and the base or seat of the chair. When a user directly applies force to the backrest frame 110, or when the user leans back on the backrest main body 120 and tilts backward, causing the backrest frame 110 to rotate backward, the interlocking mechanism interlocks the sliding member 131, specifically, pulls the sliding member 131, allowing the sliding member 131 to slide on the backrest frame 110, thereby causing the backrest main body 120 to slide relative to the backrest frame 110. Third, the sliding member 131 is further connected to other components of the chair (e.g., the headrest 300). Applying force to the corresponding member acts on the sliding member 131 and the backrest frame 110 simultaneously, causing the backrest frame 110 to rotate backward and the sliding member 131 to slide on the backrest frame 110, thereby supporting the backrest main body 120 to slide relative to the backrest frame 110.

[0040] That is, when the backrest frame 110 rotates relative to the base 200, the backrest main body 120 slides on the backrest frame 110 by the sliding member 131, and the sliding member 131 supports the sliding of the backrest main body 120 on the backrest frame 110. Alternatively, the sliding member 131 slides on the backrest frame 110, causing the backrest main body 120 to slide relative to the backrest frame 110.

[0041] In this embodiment, when a user sits on the chair and leans back against the backrest main body 120, the backrest main body 120 and the backrest frame 110 rotate relative to the base 200, and at the same time, the sliding member 131 slides (e.g., slides downward) on the backrest frame 110, causing the backrest main body 120 to move (e.g., slide downward). This adjusts the position and / or angle of the backrest main body 120, allowing the backrest main body 120 to follow and support the user's body part (e.g., back), self-adapting to changes in the user's sitting posture and improving the user's comfort when using the chair.

[0042] In some embodiments, referring to FIGS. 2 and 3, the back frame 110 is provided with a sliding cavity Q extending in the longitudinal direction thereof, and the sliding member 131 is inserted into the sliding cavity Q and is in sliding engagement with the sliding cavity Q.

[0043] The sliding cavity Q provided in the backrest frame 110 is fitted with the sliding member 131. The sliding member 131 is inserted into the sliding cavity Q and slidably mounted on the backrest frame 110. Here, the sliding member 131 may be a sliding rod. Optionally, the sliding cavity Q is located at the top of the backrest frame 110, and a cavity opening Qk communicating with the sliding cavity Q is formed at the top end of the backrest frame 110. The cavity opening Qk is fitted with the outer contour of the sliding member 131, and the sliding member 131 is inserted into the sliding cavity Q through the cavity opening Qk. Here, the extension length of the sliding cavity Q is not limited and can be set according to actual circumstances.

[0044] When the backrest frame 110 rotates, the sliding member 131 correspondingly slides along the sliding cavity Q. For example, when a user sits on the chair and leans back against the backrest, the backrest frame 110 rotates on the base 200 toward the rear of the chair, and at this time, the sliding member 131 slides downward along the sliding cavity Q of the backrest frame 110 (the sliding member 131 continuously slides from the position of the cavity opening Qk toward the inside of the sliding cavity Q), moving all or part of the backrest main body 120 downward and adjusting the position and / or angle of the backrest main body 120. Alternatively, when the user switches from a leaning back position to a sitting upright position, the backrest frame 110 rotates on the base toward the front of the chair, and at this time the sliding member 131 slides upward along the sliding cavity Q of the backrest frame 110 (the sliding member 131 slides from the inside of the sliding cavity Q toward the outside of the cavity opening Qk), moving all or part of the backrest main body 120 upward and adjusting the position and / or angle of the backrest main body 120.

[0045] Here, the sliding member 131 is inserted into the sliding cavity Q formed in the backrest frame 110, and is slidably mounted on the backrest frame 110, and does not occupy additional thickness space along the front-to-back direction of the chair, and does not occupy additional width space along the left-to-right direction of the chair.

[0046] In some embodiments, at least one of the back frame 110 and the sliding member 131 is provided with a sliding structure for supporting the sliding member 131 sliding along the sliding cavity Q.

[0047] The sliding member 131 slides along the sliding cavity Q with the support of the sliding structure. The sliding structure may be provided on the back frame 110, on the sliding member 131, or on both the back frame 110 and the sliding member 131 at the same time.

[0048] Here, the sliding structure may have a variety of structural forms. For example, the sliding structure may include a sliding groove, and a portion of the sliding member 131 is accommodated in the sliding groove and slides with the support of the sliding groove. This is merely an example and is not limiting. In a specific application, when a sliding structure is provided on either the backrest frame 110 or the sliding member 131, the structural form of the sliding structure is not limited to one type.

[0049] The support of the sliding structure allows the sliding member 131 to slide stably along the sliding cavity Q, which is advantageous to improving the running stability of the backrest sliding system.

[0050] In some embodiments, referring to FIG. 3, the sliding structure includes at least one support member 10 that is rotatably mounted on one of the back frame 110 and the sliding member 131 and forms rolling contact between the other of the back frame 110 and the sliding member 131.

[0051] The sliding structure employs support members 10 that are rotatably mounted on an installation object (the backrest frame 110 or the sliding member 131) and are disposed on a wall surface of the installation object to contact the other object. Optionally, at least one support member 10 is rotatably mounted on the backrest frame 110 and is located on the inner wall of the sliding cavity Q to form rolling contact with the sliding member 131.

[0052] Here, at least one support member 10 is provided, i.e., one support member 10 may be provided, or one or more (for example, two or three) support members 10 may be provided. When one or more support members 10 are provided, the one or more support members 10 may be arranged at intervals along the circumferential direction, horizontal direction, or vertical direction of the installation object. Optionally, the support member 10 may include a support wheel to which a mounting shaft is connected. A mounting groove is formed in the wall surface of the installation object, and at least a portion of the support wheel is received in the mounting groove and is rotatably mounted on the wall surface of the installation object by the mounting shaft.

[0053] When the sliding member 131 slides along the sliding cavity Q, the support member 10 in contact with the sliding member 131 or the back frame 110 rotates accordingly. That is, the support member 10 rolls along the surface of the sliding member 131 or the back frame 110, supporting the sliding member 131 sliding along the sliding cavity Q. The provided support member 10 can greatly reduce the frictional resistance between the back frame 110 and the sliding member 131, allowing the sliding member 131 to perform a sliding operation more easily and making the sliding process smoother.

[0054] Optionally, at least one support member 10 is rotatably mounted on one of the backrest frame 110 and the sliding member 131, and the other is provided with a sliding groove extending in its longitudinal direction. The support member 10 is accommodated in the sliding groove and forms rolling contact with the groove bottom wall of the sliding groove. Here, the sliding groove provides a clear movement locus for the support member 10, ensuring that the support member 10 moves along a predetermined direction and realizing high-precision guiding of the sliding member 131 for sliding.

[0055] Optionally, both the backrest frame 110 and the sliding member 131 are provided with a support member 10. The support member 10 of the backrest frame 110 is located on the inner wall of the sliding cavity Q and is provided close to the cavity opening Qk. The support member 10 of the sliding member 131 is located at its bottom. This structural arrangement allows the sliding member 131 to balance the force it receives during the sliding process, making it less likely to jam and ensuring smooth sliding of the sliding member 131.

[0056] 1, 4 and 5, in some embodiments, the first transmission unit 130 further includes a first support member 132 rotatably connected to the sliding member 131. The sliding member 131 is transmission-connected to the backrest body 120 by the first support member 132.

[0057] The first support member 132 is provided between the sliding member 131 and the backrest main body 120. In addition to supporting the backrest main body 120, the first support member 132 also establishes a power transmission connection between the sliding member 131 and the backrest main body 120. Force can be transmitted between the sliding member 131 and the backrest main body 120 through the provided first support member 132. For example, when the sliding member 131 slides on the backrest frame 110, the first support member 132 causes the backrest main body 120 to slide relative to the backrest frame 110.

[0058] Here, the first support member 132 and the sliding member 131 are rotatably connected to each other, forming a mutually rotatable connection relationship. The first support member 132 is also connected to the backrest main body 120. The connection may be direct connection or connection via an intermediate member, and may be a rotational connection, sliding connection, or other connection method, but is not limited to this embodiment. When a user leans against the backrest main body 120, the backrest main body 120 receives a force applied by the user. As the user's sitting posture changes, the force received by the backrest main body 120 (e.g., the magnitude, direction, position, etc. of the force) changes correspondingly and is transmitted to the first support member 132. As a result, the first support member 132 rotates the backrest main body 120 relative to the sliding member 131, and the backrest main body 120 adaptively adjusts its angle and / or position to provide support by adhering to the human body part. It has excellent adhesion and support, which is advantageous in improving the comfort of the user when using the chair.

[0059] The connection structure between the first support member 132 and the sliding member 131 can be set in the following two types. First, a backrest connecting portion is formed on the sliding member 131, and a connecting shaft is inserted into the backrest connecting portion. The first support member 132 is connected to the connecting shaft and forms a hinged connection (i.e., a rotational connection) with the backrest connecting portion. This allows the first support member 132 to rotate relative to the sliding member 131 via the connecting shaft. In the second configuration, a backrest connection portion is formed on the sliding member 131, and a sliding hole is formed in the backrest connection portion. A sliding shaft is inserted into the sliding hole, and the first support member 132 is connected to the sliding shaft or is integrally formed with the sliding shaft, thereby forming a rotational connection and sliding connection relationship with the backrest connection portion. As a result, the first support member 132 can rotate relative to the sliding member 131 through the sliding shaft and slide relative to the sliding member 131. In this way, when the backrest main body 120 moves relative to the sliding member 131, the position and / or angle of the backrest main body 120 can be changed diversified, allowing the backrest main body 120 to fit more closely to the human body parts and provide sufficient support. The above two structural configurations are merely examples and are not limiting.

[0060] Alternatively, the first support member 132 may have two support portions disposed opposite each other, located on opposite sides of the first support member 132, and connected to the backrest main body 120. The two support portions extend perpendicularly to the first support member 132 on opposite sides of the first support member 132, and the first support member 132 may be coupled with the two support portions thereon to form an "H"-shaped member. Alternatively, the support portions may not be elongated, and may have a structural shape such as a square, circle, or triangle. Here, the support portions may be directly connected to the backrest main body 120 or may be connected to the backrest main body 120 via another intermediate member.

[0061] Optionally, the support part and the backrest main body 120 are movably connected. Here, the form of the movably connected part includes a rotational connection, a sliding connection, an elastic connection, etc., and is not limited in this embodiment. Since the support part and the backrest main body 120 are movably connected, the backrest main body 120 is allowed to move relative to the first support member 132 and can adjust according to different user's body shapes and / or postures, adapt to the human body shape and posture, and provide support and cushioning.

[0062] 4 to 8, in some embodiments, the first transmission unit 130 further includes at least two sets of second support members 133, each provided on opposite sides of the first support member 132. Here, each set of second support members 133 includes at least one second support member 133, and each second support member 133 is movably connected to the first support member 132, and the first support member 132 is movably connected to the backrest main body 120 via the at least two sets of second support members 133.

[0063] Specifically, the first transmission unit 130 includes, in addition to the sliding member 131 and the first support member 132, at least two sets of second support members 133, each provided on opposite sides of the first support member 132. The second support members 133 are located between the first support member 132 and the backrest main body 120, and are movably connected to the first support member 132 and the backrest main body 120. Here, the form of the movably connected structure may refer to, but is not limited to, one of the two forms of the connecting structure between the first support member 132 and the sliding member 131 in the above-described embodiment.

[0064] 8 and 9, the connection structure between the second support member 133 and the first support member 132 may be configured as follows: A first slide rail 1321 is formed on the first support member 132, and a first slide pin 1331 is inserted into the first slide rail 1321. The second support member 133 is connected to the first slide pin 1331 or is integrally formed with the first slide pin 1331, thereby forming a rotational and sliding connection relationship with the first support member 132. As a result, the second support member 133 can rotate relative to the first support member 132 by the first slide pin 1331 and can slide relative to the first support member 132. As such, when the backrest main body 120 moves relative to the first support member 132, the position and / or angle of the backrest main body 120 can be varied, allowing the backrest main body 120 to fit more closely to the human body parts and provide sufficient support.

[0065] One or more second support members 133, each of which is movably connected to the backrest main body 120, may be provided at opposite sides of the first support member 132. By providing a movably connection between the first support member 132 and the backrest main body 120 via the second support member 133, the relative movement between the backrest main body 120 and the first support member 132 can be made more flexible, allowing the backrest main body 120 to better fit the curves of the human body and provide more comfortable support.

[0066] 5 to 9, in some embodiments, a first accommodating cavity Q1 is provided in one of the backrest main body 120 and the second support member 133, and a first engaging member J1 is provided in the other. The first engaging member J1 is accommodated in the first accommodating cavity Q1, thereby movably connecting the second support member 133 and the backrest main body 120.

[0067] Specifically, a first accommodating cavity Q1 can be provided on the backrest main body 120, and a first engaging member J1 can be provided on the second support member 133. The second support member 133 is accommodated in the first accommodating cavity Q1 on the backrest main body 120 by the first engaging member J1, thereby forming a movably connected relationship with the backrest main body 120. Alternatively, the first accommodating cavity Q1 can be provided on the second support member 133, and the first engaging member J1 can be provided on the backrest main body 120. The backrest main body 120 is accommodated in the first accommodating cavity Q1 on the second support member 133 by the first engaging member J1, thereby forming a movably connected relationship with the second support member 133.

[0068] Here, the first engaging member J1 can be a ball joint, an elastic member (e.g., a spring), soft silicone, etc., but is not limited to these in this embodiment. If the first engaging member J1 is a ball joint, the ball connecting end of the ball joint is accommodated in the first receiving cavity Q1 and can move and / or rotate within the first receiving cavity.

[0069] The movable connection between the provided first engagement member J1 and the backrest main body 120 allows the backrest main body 120 to rotate and / or move in multiple directions relative to the second support member 133, overcoming the limitations of conventional fixed connections and allowing the backrest main body 20 to be adaptively adjusted according to the user's sitting posture.

[0070] For example, if the first engagement member J1 employs a ball joint, when the user leans back on the backrest main body 120, the first engagement member J1 can move within the first accommodation cavity Q1. When the user changes their posture to lean back / lie down, the first engagement member J1 moves and / or rotates within the first accommodation cavity Q1, thereby causing the backrest main body 120 to correspondingly adjust its angle and / or position relative to the second support member 133. This allows the backrest main body 120 to adapt to the curves of the human body when the user leans back / lie down, improving the comfort of support.

[0071] 1 and 2, in some embodiments, the second transmission unit 140 includes a rotating member 141, one end of which is rotatably connected to the backrest frame 110 and the other end of which is transmission-connected to the backrest main body 120. The rotating member 141 is attached to the backrest frame 110 and can rotate on the backrest frame 110. Specifically, the rotating member 141 can adopt a structural form such as a rotating rod, a rotating frame, a link, etc., and is rotatably connected to the backrest frame 110 to realize rotatable installation on the backrest frame 110. In the backrest frame 110, the rotating member 141 can be provided at the lower part of the backrest frame 110, corresponding to the lower half of the backrest main body 120 (which can also be regarded as the part of the backrest that supports the lumbar region of the human body). The backrest main body 120 and the rotating member 141 are in a transmission connection relationship, and the rotating member 141 allows the backrest main body 120 to rotate relative to the backrest frame 110, and the rotating member 141 supports the rotation of the backrest main body 120 on the backrest frame 110.

[0072] The power source for the rotation of the rotating member 141 can be as follows: When a user leans against the backrest main body 120 and the user leans back, the acting force applied to the backrest main body 120 increases, and the acting force received by the backrest main body 120 acts on the rotating member 141 and the backrest frame 110 simultaneously, so that the backrest frame 110 rotates backward correspondingly, and at the same time, the rotating member 141 rotates on the backrest frame 110, thereby supporting the rotation of the backrest main body 120 relative to the backrest frame 110.

[0073] That is, when the backrest frame 110 rotates relative to the base, the backrest main body 120 rotates on the backrest frame 110 by the rotating member 141 .

[0074] In this embodiment, when a user sits in the chair and leans back against the backrest main body 120, the backrest main body 120 and the backrest frame 110 rotate relative to the base 200, and at the same time, the rotating member 141 rotates on the backrest frame 110 (for example, one end of the rotating member 141 connected to the backrest main body 120 rotates downward), causing the backrest main body 120 to move (for example, move toward the base). This adjusts the position and / or angle of the backrest main body 120, allowing the backrest main body 120 to follow and support the user's body parts (for example, the back), self-adapting to changes in the user's sitting posture and improving the comfort of the user when using the chair.

[0075] 4 to 7, in some embodiments, the second transmission unit 140 further includes a third support member 142 that is rotatably connected to the rotating member 141. The rotating member 141 is transmission-connected to the backrest main body 120 by the third support member 142.

[0076] The third support member 142 is provided between the rotating member 141 and the backrest main body 120. In addition to supporting the backrest main body 120, the third support member 142 also establishes a power transmission connection between the rotating member 141 and the backrest main body 120. The rotating member 141 and the backrest main body 120 can transmit force through the third support member 142. For example, when the rotating member 141 rotates on the backrest frame 110, the third support member 142 correspondingly rotates the backrest main body 120 relative to the backrest frame 110.

[0077] Here, the third support member 142 and the rotating member 141 are rotatably connected to each other, forming a mutually rotatable connection relationship. The third support member 142 is also connected to the backrest main body 120. The connection may be a direct connection or a connection via an intermediate member, and may be a rotational connection, sliding connection, or other connection method, but is not limited to this embodiment. When a user leans against the backrest main body 120, the backrest main body 120 receives a force applied by the user. As the user's sitting posture changes, the force received by the backrest main body 120 (e.g., the magnitude, direction, position, etc. of the force) correspondingly changes and is transmitted to the third support member 142. As a result, the third support member 142 rotates the backrest main body 120 relative to the rotating member 141, and the backrest main body 120 adaptively adjusts its angle and / or position to provide support by closely fitting to the human body part. This structure provides excellent adhesion and support, and is advantageous in improving the comfort of the user when using the chair.

[0078] The connection structure between the third support member 142 and the rotating member 141 can be set in the following two types. First, a backrest connecting portion is formed on the rotating member 141, and a connecting shaft is inserted into the backrest connecting portion. The third support member 142 is connected to the connecting shaft so as to form a hinged (i.e., pivotal) relationship with the backrest connecting portion, whereby the third support member 142 can rotate relative to the rotating member 141 via the connecting shaft. In the second configuration, a backrest connection portion is formed on the pivoting member 141, and a sliding hole is formed in the backrest connection portion. A sliding shaft is inserted into the sliding hole, and the third support member 142 is connected to the sliding shaft, thereby simultaneously forming a hinge connection (i.e., a pivot connection) and a sliding connection relationship with the backrest connection portion. As a result, the third support member 142 can rotate relative to the pivoting member 141 through the sliding shaft, and can also slide relative to the pivoting member 141. In this way, when the backrest main body 120 moves relative to the third support member 142, the position and / or angle of the backrest main body 120 can be changed in a variety of ways, allowing the backrest main body 120 to fit more closely to the human body parts and provide sufficient support. The above two types of structural configurations are merely examples and are not limiting.

[0079] Here, when the first support member 132 is taken as the reference object, a corresponding support portion can also be provided for the third support member 142, and the specific structural settings can be referred to the above embodiments and will not be described in detail here.

[0080] 4 , in some embodiments, the second transmission unit 140 further includes at least two sets of fourth support members 143, each set being provided on opposite sides of the third support member 142. Here, each set of fourth support members 143 includes at least one fourth support member 143, and each fourth support member 143 is movably connected to the third support member 142. The third support member 142 is movably connected to the backrest body 120 by at least two sets of fourth support members 143.

[0081] Specifically, the second transmission unit 140 includes, in addition to the rotating member 141 and the third support member 142, at least two sets of fourth support members 143, each provided on opposite sides of the third support member 142. The fourth support members 143 are located between the third support member 142 and the backrest main body 120, and are movably connected to the third support member 142 and the backrest main body 120. Here, the form of the movably connected structure may refer to, but is not limited to, one of the two forms of the connecting structure between the third support member 142 and the rotating member 141 in the above-described embodiment.

[0082] Here, the connection structure between the fourth support member 143 and the third support member 142 may be configured as follows: A second slide rail is formed on the third support member 142, and a second slide pin is inserted into the second slide rail. The fourth support member 143 is connected to the second slide pin or is integrally formed with the second slide pin, thereby simultaneously forming a rotational and sliding connection relationship with the third support member 142. As a result, the fourth support member 143 can rotate relative to the third support member 142 through the second slide pin and can also slide relative to the third support member 142. In this way, when the backrest main body 120 moves relative to the third support member 142, the position and / or angle of the backrest main body 120 can be changed diversified, allowing the backrest main body 120 to fit more closely to the human body parts and provide sufficient support.

[0083] One or more fourth support members 143 that are movably connected to the backrest main body 120 can be provided at opposite sides of the third support member 142. By setting the fourth support member 143 to be movably connected between the third support member 142 and the backrest main body 120, the relative movement between the backrest main body 120 and the third support member 142 can be made more flexible, allowing the backrest main body 120 to better fit the curves of the human body and provide more comfortable support.

[0084] 6, 7 and 10, in some embodiments, a second receiving cavity Q2 is provided in one of the backrest main body 120 and the fourth support member 143, and a second engaging member J2 is provided in the other. The second engaging member J2 is received in the second receiving cavity Q2 to movably connect the fourth support member 143 and the backrest main body 120.

[0085] Specifically, a second accommodating cavity Q2 may be provided on the backrest main body 120, and a second engaging member J2 may be provided on the fourth support member 143. The fourth support member 143 is accommodated in the second accommodating cavity Q2 on the backrest main body 120 by the second engaging member J2, thereby forming a movably connected relationship with the backrest main body 120. Alternatively, the second accommodating cavity Q2 may be provided on the fourth support member 143, and a second engaging member J2 may be provided on the backrest main body 120. The backrest main body 120 is accommodated in the second accommodating cavity Q2 on the fourth support member 143 by the second engaging member J2, thereby forming a movably connected relationship with the fourth support member 143.

[0086] Here, the second engaging member J2 can be a ball joint, an elastic member (e.g., a spring), soft silicone, etc., but is not limited to these in this embodiment. If the second engaging member J2 is a ball joint, the ball connecting end of the ball joint is accommodated in the second receiving cavity Q2 and can move and / or rotate within the second receiving cavity Q2.

[0087] The movable connection between the provided second engagement member J2 and the backrest main body 120 allows the backrest main body 120 to rotate and / or move in multiple directions relative to the fourth support member 143, overcoming the limitations of conventional fixed connections and allowing the backrest main body 120 to be adaptively adjusted according to the user's sitting posture.

[0088] For example, if the second engagement member J2 employs a ball joint, when the user leans on the backrest main body 120, the second engagement member J2 can move within the second accommodation cavity Q2. As the user leans back / lies down, the second engagement member J2 moves and / or rotates within the second accommodation cavity Q2, thereby correspondingly adjusting the angle and / or position of the backrest main body 120 relative to the fourth support member 143. This allows the backrest main body 120 to adapt to the curves of the human body when the user leans back / lies down, improving the comfort of support.

[0089] 2 , in some embodiments, the backrest assembly 100 further includes a first interlocking member 151, one end of which is hingedly connected to the first transmission unit 130 and the other end of which is hingedly connected to the second transmission unit 140. In this embodiment, the first interlocking member 151 forms a stable linkage between the first transmission unit 130 and the second transmission unit 140. That is, a cooperative operating mechanism exists between the second transmission unit 140, the first interlocking member 151, and the first transmission unit 130. For example, when the second transmission unit 140 operates as a result of the backrest frame 110 rotating relative to the base or the backrest main body 120 operating relative to the backrest frame 110, the second transmission unit 140 operates the first transmission unit 130 via the first interlocking member 151.

[0090] Combining the above embodiments, depending on the configurations adopted by the first transmission unit 130 and the second transmission unit 140, one end of the first interlocking member 151 may be hingedly connected to the sliding member 131, and the other end of the first interlocking member 151 may be hingedly connected to the rotating member 141. Here, the first interlocking member 151 may be the first interlocking link 151. For example, when a user leans back against the backrest main body 120, the backrest frame 110 rotates toward the rear of the chair, and the rotating member 141 rotates correspondingly, transmitting and operating the first interlocking link 151. The first interlocking link 151 pulls the sliding member 131, causing it to move downward from its initial position. When the user switches from a leaning back position to a straight-sitting position, the back frame 110 rotates toward the front of the chair, and the rotating member 141 rotates accordingly, transmitting power to the first interlocking link 151 to operate. The first interlocking link 151 moves the sliding member 131 upward and returns it to its initial position.

[0091] 1 and 2, in some embodiments, the backrest assembly 100 further includes a second linkage member 152, one end of which is hingedly connected to the second transmission unit 140 and the other end of which is hingedly connected to the chair base 200. In this embodiment, since the connection relationship between the second transmission unit 140 and the backrest main body 120 and the backrest frame 110 is movable, the backrest main body 120, the second transmission unit 140 and the backrest frame 110 constitute a free mechanism. By further providing the second interlocking member 152 as a supporting base for the second transmission unit 140 or the backrest main body 120, when the backrest main body 120 and / or the backrest frame 110 are not subjected to external force, the second transmission unit 140 or the backrest main body 120 can be kept stable relative to the base 200, so that the backrest main body 120, the second transmission unit 140, the backrest frame 110 and the second interlocking member 152 form a stable link mechanism. At the same time, the second interlocking member 152 also forms a link relationship with the second transmission unit 140, and there is a mutually cooperative operating mechanism between the second interlocking member 152 and the second transmission unit 140. When the second transmission unit 140 operates as a result of the backrest frame 110 rotating relative to the base 200 or the backrest main body 120 moving relative to the backrest frame 110, the second transmission unit 140 can move relative to the base 200 through the second interlocking member 152. In this process, the second interlocking member 152 moves correspondingly and plays a role in supporting the second transmission unit 140 and thereby supporting the backrest main body 120.

[0092] Combining the above embodiments, depending on the configuration adopted by the second transmission unit 140, one end of the second interlocking member 152 may be hingedly connected to the rotating member 141, and the other end of the second interlocking member 152 may be hingedly connected to the base 200. Here, the second interlocking member 152 may be a second interlocking link 152.

[0093] In some embodiments, referring to FIGS. 6 and 7 , the backrest main body 120 is provided with a plurality of openings K located on the lateral edges of the backrest main body 120. Each opening K extends from the edge of one lateral edge toward the other lateral edge. Specifically, the openings K are located on the lateral edges of the backrest main body 120 along the lateral direction of the backrest main body 120 (which can also be considered the left-right direction of the backrest main body 120) and extend toward the opposite lateral edge. Optionally, the openings K are strip-shaped openings. A plurality of openings K may be provided, i.e., two or more openings K may be provided, and the specific number of openings K can be determined according to actual needs. The extension lengths of the openings K may be the same or different, but this is not limited in this embodiment. For example, the left side of the backrest body 120 has at least one first opening extending toward the right side, and / or the right side of the backrest body 120 has at least one second opening extending toward the left side.

[0094] Here, the plurality of openings K are divided into two sets of openings K provided opposite to each other along the lateral direction of the backrest main body 120, and each set of openings K includes at least one opening K.

[0095] For ease of understanding, the two sets of openings K can be divided into a first set of openings and a second set of openings. Along the lateral direction of the backrest main body 120, the first set of openings is located on the left side of the backrest main body 120, and the second set of openings is located on the right side of the backrest main body 120, with the first openings and the second openings being arranged opposite each other.

[0096] The set of first openings may include one first opening or may include a plurality (two or more) of first openings. When a plurality of first openings are provided, the plurality of first openings are arranged at intervals in sequence along the vertical direction of the backrest main body 120. For example, seven first openings are located on the left side of the backrest main body 120 and are arranged at intervals in sequence along the vertical direction of the backrest main body 120.

[0097] The set of second openings may include one second opening or multiple (two or more) second openings. When multiple second openings are provided, the multiple second openings are arranged at intervals along the longitudinal direction of the backrest main body 120. For example, seven second openings are located on the right side of the backrest main body 120 and arranged at intervals along the longitudinal direction of the backrest main body 120.

[0098] Optionally, the first openings and the second openings are the same in number and in positions corresponding to each other.

[0099] Due to the presence of the opening K, when a user leans against the backrest main body 120, the backrest main body 120 can adaptively deform to fit the curves of the user's body, thereby providing sufficient support by fitting closely to the user's body parts and adapting to changes in the body shape and posture of different users.

[0100] 6 and 7, in some embodiments, the backrest main body 120 includes a plurality of support ribs 121 spaced apart along the longitudinal direction of the backrest main body 120. A gap between any two adjacent support ribs 121 is formed as the opening K.

[0101] The support rib 121 is generally elongated or plate-shaped and may be a separate component or integrated with another structure. A plurality of support ribs 121 (two or more) are provided. The plurality of support ribs 121 are arranged in sequence at intervals along the longitudinal direction of the backrest main body 120. The number of support ribs 121 is not limited to that in this embodiment and may be set as needed, for example, eight. The support ribs 121 may also be provided on one side along the transverse direction of the backrest main body 120. For example, a plurality of support ribs 121 may be provided on the left or right side of the backrest main body 120. Alternatively, the support ribs 121 may be provided on both sides. For example, a plurality of support ribs 121 may be provided on the left and right sides of the backrest main body 120. The different shapes and dimensions (e.g., length, width, etc.) of the support ribs 121 allow for better fit to the user's body parts and provide personalized support to users with different body types.

[0102] Since the support ribs 121 are disposed at intervals, a gap formed between any two adjacent support ribs 121 can be formed as an opening K. Here, by setting the interval between the support ribs 121, the size of the opening K can be determined accordingly. The support ribs 121 may be connected to each other, i.e., may have a structural connection relationship, or may not be connected to each other. If the support ribs 121 are not connected to each other, a structural connection can be established between the support ribs 121 by connecting them to the transmission units (first transmission unit 130 and / or second transmission unit 140), but this is not limited to this embodiment.

[0103] For example, any two adjacent support ribs 121 are connected by a connecting portion 122. Specifically, the connecting portion 122 is formed between the two adjacent support ribs 121. The connecting portion 122 can be integrally molded with the support ribs 121, thereby connecting the two adjacent support ribs 121. The connected support ribs 121 form a frame for the entire backrest main body 120, improving the structural strength and support of the backrest main body 120. Furthermore, the connection between the support ribs 121 by the connecting portion 122 can more uniformly distribute pressure throughout the entire backrest main body 120. One or more (two or more) connecting portions 122 may be provided between the two adjacent support ribs 121. The multiple connecting portions 122 are arranged at intervals along the lateral direction of the backrest main body 120, but this is not limited to this embodiment.

[0104] Here, when a user leans on the backrest body 120, as the leaning posture changes, the backrest body 120 adopts a spaced rib structure design, so the backrest body 120 can deform adaptively, with good deformation effect, providing the user with a good flexible support effect.

[0105] The embodiments of the present application further provide a chair including a base 200 and the chair back assembly 100 described in the above embodiments, in which a back frame 110 is connected to the base 200. The connection manner between the back frame 110 and the base 200 includes a fixed connection or a rotatable connection. For the specific configuration of the chair back assembly 100, please refer to the above embodiments. This chair adopts all the technical solutions of all the above embodiments, and therefore has at least all the technical effects brought about by the technical solutions of the above embodiments, which will not be described one by one here.

[0106] The above description is merely a part or preferred embodiment of the present application, and the protection scope of the present application cannot be limited by the text or drawings. Based on the overall concept of the present application, equivalent structural modifications made using the contents of the specification and drawings of the present application, or directly / indirectly operating in other related technical fields, are all included in the protection scope of the present application.

Claims

1. a back frame connected to the base of the chair; a backrest body provided on one side of the backrest frame; a first transmission unit provided between the backrest frame and the backrest body and transmission-connected to the backrest body; a second transmission unit provided between the backrest frame and the backrest body, and arranged at an interval from the first transmission unit along the longitudinal direction of the backrest frame, and transmission-connected to the backrest body; A chair backrest assembly, characterized in that the first transmission unit is slidably connected to the backrest frame, and the second transmission unit is rotatably connected to the backrest frame so that the backrest main body can move relative to the backrest frame when an external force is applied to the backrest assembly.

2. 2. The chair back assembly according to claim 1, wherein the first transmission unit includes a sliding member slidably mounted on the back frame and transmission-connected with the back body.

3. The backrest frame is provided with a sliding cavity extending in a longitudinal direction, 3. The chair back assembly of claim 2, wherein said slide member is inserted into said slide cavity and is in sliding engagement with said slide cavity.

4. a sliding structure is provided on at least one of the backrest frame and the sliding member; 4. The chair back assembly of claim 3, wherein the sliding structure is for supporting the sliding member sliding along the sliding cavity.

5. 5. The chair back assembly according to claim 4, wherein the sliding structure includes at least one support member rotatably mounted on one of the back frame and the sliding member and in rolling contact with the other of the back frame and the sliding member.

6. The first transmission unit further includes a first support member rotatably connected to the sliding member, 6. The chair back assembly according to claim 2, wherein the sliding member is power-transmittingly connected to the back body via the first support member.

7. the first transmission unit further includes at least two pairs of second support members respectively provided on opposite sides of the first support member; each set of second support members includes at least one second support member movably connected to the first support member; 7. The chair back assembly according to claim 6, wherein the first support member is movably connected to the back body via at least two pairs of the second support members.

8. a first receiving cavity is provided in one of the backrest body and the second support member, and a first engaging member is provided in the other; 8. The chair back assembly according to claim 7, wherein the first engagement member is received in the first receiving cavity so as to movably connect the second support member and the back body.

9. 2. The chair back assembly according to claim 1, wherein the second transmission unit includes a rotating member having one end rotatably connected to the back frame and the other end power-transmittingly connected to the back body.

10. the second transmission unit further includes a third support member rotatably connected to the rotating member, 10. The chair back assembly according to claim 9, wherein the rotating member is power-transmittingly connected to the back body via the third support member.

11. the second transmission unit further includes at least two pairs of fourth support members respectively provided on opposite sides of the third support member; each set of the fourth support members includes at least one fourth support member movably connected to the third support member; 11. The chair back assembly according to claim 10, wherein the third support member is movably connected to the back body via at least two sets of the fourth support members.

12. a second receiving cavity is provided in one of the backrest body and the fourth support member, and a second engaging member is provided in the other; 12. The chair back assembly according to claim 11, wherein the second engagement member is received in the second receiving cavity so as to movably connect the fourth support member and the back body.

13. 2. The chair back assembly of claim 1, further comprising a first linkage member having one end hingedly connected to the first transmission unit and the other end hingedly connected to the second transmission unit.

14. 2. The chair back assembly of claim 1, further comprising a second linkage member having one end hinged to the second transmission unit and another end hinged to the chair base.

15. A plurality of openings are provided in the backrest body, The plurality of openings are located on the side edges along the lateral direction of the backrest body, 2. The chair back assembly of claim 1, wherein each of said openings extends from an edge of one side thereof toward the other side.

16. The backrest body includes a plurality of support ribs spaced apart along a longitudinal direction of the backrest body; 16. The chair back assembly according to claim 15, wherein the opening is defined as a gap between any two adjacent support ribs.

17. With the base, a chair back assembly according to any one of claims 1 to 16; The chair is characterized in that the back frame is connected to the base.

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