Backrest of Height-Adjustable Chair

This application is a continuation of PCT application serial no. PCT/CN2025/088307, filed on Apr. 10, 2025, which claims the priority and benefit of Chinese patent application serial no. 202410802475.6, filed on Jun. 20, 2024. The entireties of PCT application serial no. PCT/CN2025/088307 and Chinese patent application serial no. 202410802475.6 are hereby incorporated by reference herein and made a part of this specification.

The present application relates to the field of chair structures, and, more particularly, to a backrest of a height-adjustable chair.

A height-adjustable chair is a new type of chair, which mainly includes a seat pan, a backrest, a bracket, a bracket rocker, a height positioning device and chair legs, which is characterized in that the bracket is hinged with the chair legs through the respective bracket rocker, the bracket rocker rotates up and down around a pivot shaft articulated to the chair legs. When the bracket rocker is swung, the bracket is driven to lift and lower, so as to lift and lower the seat pan.

In addition, a height positioning device is further provided between the bracket and the chair legs. The current height-adjustable chairs have a variety of classifications, and have been widely used in people's work and learning and production sites. It has certain ergonomics, which is beneficial to health.

With the rise of prolonged remote work and gaming sessions, rigid, formulaic office

spaces can no longer meet people's needs. Therefore, office furniture featuring vibrant colors, unique designs, and user-friendly functionality—prioritizing individual expression and human-centric design—is becoming increasingly prevalent. However, relying solely on aesthetics or isolated functionality falls short, these designs must harmonize professional-grade with personalized customization. During work, the first step is to adjust the desk or workstation to an optimal height based on task requirements. Different desk heights demand specific seating arrangements, sometimes even necessitating a different chair entirely. Current market offerings include diverse chair designs, where the backrest plays a pivotal role in user comfort and experience. Traditional backrests often employ fixed structures, which are not adjustable according to user's demands, while lacking in aesthetic versatility and ease of maintenance.

In order to make the backrest more flexible in use, the present application provides a backrest of a height-adjustable chair.

The backrest of a height-adjustable chair of the present application adopts the following technical solution.

A backrest of a height-adjustable chair includes:

Optionally, the backrest frame body is a frame body with a space in the middle, a cam is provided between the backrest frame body and the S-shaped frame body, and a connecting lug for mounting the cam is provided on the backrest frame body;

Optionally, the S-shaped frame body includes a first curved portion and a second curved portion, where the second curved portion is located close to the height-adjustable seat, the first curved portion is connected to the second curved portion and the first curved portion is located above the second curved portion, the first curved portion and the second curved portion are curved away from each other, and a lower half of the backrest plate aligns flush with the first curved portion.

Optionally, textures are uniformly provided on the backrest plate, the textures are configured to ensure comfort after the backrest plate is bent, an upper half of the backrest plate is defined as a first backrest plate while the lower half of the backrest plate is defined as a second backrest plate, and a thickness of the first backrest plate is smaller than a thickness of the second backrest plate.

Optionally, the first curved portion has a curvature, and the second curved portion is uniformly configured with a plurality of cushioning grooves on a surface facing the height-adjustable seat.

Optionally, the cushioning grooves are L-shaped.

Optionally, the backrest connection unit is L-shaped, where the first mounting portion extends horizontally while the second mounting portion extends vertically, the first mounting portion is connected to the seat cushion frame;

Optionally, a height positioning structure is provided between the backrest frame body and the backrest connection unit, and the height positioning structure is configured to lock a height position of the backrest.

Optionally, a lug plate is provided at the lower end of the S-shaped frame body, the lug plate is configured with a connecting hole, and the S-shaped frame body is rotatably connected to the first mounting portion via the connecting hole.

Optionally, the S-shaped frame body is rotatably connected to a rear end of the seat

cushion frame via the connecting hole.

In summary, the present application includes at least one of the following beneficial technical effects.

This application is described in further detail below with reference to.

Disclosed in the embodiments of the present application is a backrest of a height-adjustable chair. Referring to, the backrest of the height-adjustable chair includes a height-adjustable seatand a backrest body. The height-adjustable seat includes a seat cushion frame, a seat cushionon the seat cushion frame, and a backrest connection uniton the seat cushion frame. The backrest connection unitincludes a first mounting portion and a second mounting portion for mounting a backrest body. The backrest bodyincludes a backrest frame body, a backrest plateconnected to a part of the backrest frame body, and an S-shaped frame bodybetween the backrest frame bodyand the backrest plate. A clearance for adjustmentis present between the backrest frame bodyand the backrest plate, and an S-shaped portion of the S-shaped frame bodyis located in the clearance for adjustment.

The backrest connection unitis L-shaped, where the first mounting portion extends horizontally while the second mounting portion extends vertically, and the first mounting portion is connected to the seat cushion frame. A chamber around the second mounting portion is defined at a bottom of the backrest frame body, so that the backrest frame bodycan be vertically adjusted. The chamber provides a bending space for the S-shaped frame bodywhen adjusting the height of the backrest, which prolongs the life of the seat.

One end of the backrest frame bodyclose to the height-adjustable seatis mounted at the first mounting portion, and one end of the S-shaped frame bodyclose to the height-adjustable seat is mounted at the second mounting portion. When the backrest bodyis raised, the S-shaped frame bodyis extended, and when the backrest bodyis lowered, the S-shaped frame bodyis compressed. When the backrest is raised, the S-shaped frame body is elongated and deformed in a height direction. Since the S-shape may be elastically deformed starker, and the S-shape may be elastically deformed in the vertical direction, the backrest is short when the backrest bodyis lowered, and backrest is long when the backrest bodyis raised, that is, the shape of the backrest changes with the height. The backrest is more flexible in use by the S-shaped design thereof, while ensuring the visual integrity of the backrest.

The backrest frame bodyis a frame body with a space in the middle, a camis provided between the backrest frame bodyand the S-shaped frame body, and a connecting lug for mounting the camis provided on the backrest frame body. One end of the backrest plateclose to the height-adjustable seat is provided with a mounting lug, a cam hole is formed in the mounting lug. When the backrest plateis assembled with the backrest frame body, the camis located in the cam hole. There is a space in the middle of the backrest frame bodyfor a first purpose that the weight of the backrest frame bodycan be reduced while ensuring the strength, and for a second purpose that the material can be saved so as to reduce the cost while ensuring the overall strength. After the backrest plateis connected with the backrest frame body, the shape of the backrest platechanges along with the S-shaped frame body, after the user adjusts the height, which not only ensures the integrity but also realizes that the backrest platechanges along with the S-shaped frame bodyto form an arc-shaped protrusion, which functions as a back cushion when one leans against the backrest, so that the user does not need to use a back cushion, thereby avoiding the trouble of dropping the back cushion.

In an optional embodiment, the S-shaped frame bodyincludes a first curved portionand a second curved portion, where the second curved portionis close to the height-adjustable seat, the first curved portionis connected to the second curved portionand the first curved portionis located above the second curved portion, the first curved portionand the second curved portionare curved away from each other, and a lower half of the backrest platealigns flush with the first curved portion. A lower part of the backrest platealigns flush with the first curved portionand forms a protruding arc-shaped profile along with the first curved portion, which not only ensures an integrated visual effect but also improves comfort. During use, it supports the user's back. When adjusting the height of the backrest, the position and curvature of the first curved portionwill also vary, allowing it to accommodate users of different heights during the lifting process.

In an optional embodiment, the backrest plateis uniformly provided with textures, the texturesensure comfort after the backrest plateis bent. An upper part of the backrest plateis a first backrest plate, a lower part of the backrest plateis a second backrest plate, and the thickness of the first backrest plateis smaller than that of the second backrest plate. The textureon the backrest plateis of a special shape, the texturesreduce discomfort after the backrest plateis bent and improve the comfort of the waist and the back. The thickness of the first backrest plateis smaller than that of the second backrest plateso that the first backrest platefits and wraps the back more comfortably, and the second backrest platecan support the waist and conforms to ergonomics.

The first curved portionhas a curvature, and the second curved portionis uniformly configured with a plurality of cushioning grooveson a surface thereof facing the height-adjustable seat. The curvature of the first curved portionmainly configured for supporting, and the cushioning groovesare mainly provided to increase the clearance for adjustment, so that the second curved portioncan achieve a better bending degree while reducing stress. In an optional embodiment, the cushioning grooveis L-shaped. The specially shaped groove increases deformation of the second curved portion.

A lug plate is provided at a lower end of the S-shaped frame body, the lug plate is configured with a connecting hole, and the S-shaped frame bodyis rotatably connected to the first mounting portion via the connecting hole. Optionally, the S-shaped frame bodyis rotatably connected to a rear end of the seat cushion framevia the connecting hole. The lower end of the S-shaped frame bodyis rotatably connected to the rear end of the seat cushion frameor the backrest connection unit, so as to better conform to the elongation and deformation of the S-shaped frame body, making backrest adjustment more effortless. Additionally, while meeting the requirement for large deformation, the diameter of the second curved portionof the S-shaped frame bodycan be designed smaller, so as to occupy less space, thus enhancing aesthetic appeal.

In an optional embodiment, the S-shaped frame bodyis made of a super-tough nylon material. In an optional embodiment, the outer surface of the S-shaped frame bodyis entirely wrapped with the material. Apparently, the backrest provides a smooth visual transition during height adjustment, which eliminates visual disruption in conventional designs, is more aesthetically pleasing, and the back cushion, which is additionally placed by the user, is not easily be clamped between the backrest and the seat cushion.

Optionally, a height positioning structure is provided between the backrest frame bodyand the backrest connection unit, and the height positioning structure can lock the height position of the backrest, which can prevent the unlocked backrest from changing its height, which leads to is inconvenience. The height positioning structure includes a rack on the backrest connection unit, a first redirection structure at an upper end of the rack, and a second redirection structure at a lower end of the rack. Spring-loaded locking teeth are provided on the backrest frame body, which cooperate with the rack for locking.

When the user pulls the backrest frame bodyupwards, the spring-loaded locking teeth can move upwards along the rack, and when the upward pulling is stopped, the spring-loaded locking teeth can be meshed with the rack under the action of the spring to be locked in the current position. When the spring-loaded locking teeth are aligned with the upper end of the rack, the spring-loaded locking teeth may contact the first redirection structure, thereby maintaining the spring-loaded locking teeth in a retracted state, at which time the backrest frame bodycan be lowered smoothly. When the backrest frame body is lowered to the lower end of the rack, the spring-loaded locking teeth contact the second redirection structure, so that the spring-loaded locking teeth deploys from the retracted state, so as to be meshed and locked with the rack. Since the spring-loaded locking teeth are in the retracted state when the backrest bodyis released at the uppermost position, the backrest bodymay falling directly down, and the S-shaped frame bodymay buffer the movement of such a direct falling movement, thereby preventing the impact sound caused by the direct dropping of the backrest body, and even hitting a person.

The implementation principle of the embodiments of the present application is as follows. When the backrest is raised, the S-shape is elongated and deformed in the height direction. Since the S-shape may be starker elastically deformed, and the S-shape is elastically deformed in the vertical direction, the backrest is a short backrest shape when the backrest bodyis lowered, and is a long backrest shape when the backrest bodyis raised, and the shape changes with the height, so that the backrest is more flexible in use by the S-shape and the visual integrity of the backrest is ensured. There is a space in the middle of the backrest frame bodyfor a first purpose that the weight of the backrest frame bodycan be reduced while ensuring the strength, and for a second purpose that the material can be saved so as to reduce the cost while ensuring the overall strength. After the backrest plateis connected with the backrest frame, the shape of the backrest platechanges along with the S-shaped frame body, after the user adjusts the height, which not only ensures the integrity but also realizes that the backrest platechanges along with the S-shaped frame bodyto form an arc-shaped protrusion, which functions as a back cushion when one leans against the backrest, so that the user does not need to use a back cushion, thereby avoiding the trouble of dropping the back cushion.

The above-mentioned optional embodiments of the present application do not limit the scope of protection of the present application, and therefore: all changes which come within the meaning and range of equivalence of the claims are to be embraced within their scope.