Office Chair Structure

The structure of an office chair mainly includes several parts: the basic structure, the core component for seat height adjustment, the chassis mechanism, and the pivot structure.

Basic Structure: This is the most fundamental and universal part of an office chair, encompassing the seat, backrest, armrests, legs, and small connecting components. The seat directly bears the weight of the human body, and its material and shape design affect riding comfort. The backrest provides support for the human back, helping to maintain correct sitting posture and reduce back pressure. The armrests offer support for the arms during rest or operation, reducing arm fatigue. The legs support the entire chair, ensuring its stability. Although the small connecting components are small, they play a crucial role in ensuring that all parts are firmly combined to form a complete office chair structure.

Core Component for Seat Height Adjustment: The gas spring is a common and important component. It utilizes the compressibility of gas to change the volume of gas inside the rod through manual or electric means, thereby achieving seat elevation and lowering to meet the height requirements of users of different heights. However, the claim that the five-claw base serves as the core component for height adjustment has some issues. It overlaps in function with the gas spring and is not a complete description. Typically, the five-claw base is mainly a common shape design for chair legs and is not specifically a core component for height adjustment.

Chassis Mechanism: Taking the Haworth ergonomic chair Fern as an example, the linear feel of its backrest recline is achieved through two large springs. This design makes the chair more stable and smooth when reclining. The gear lock is controlled by a cable, allowing users to easily lock the appropriate recline angle as needed. There are also small ratchets that further enhance the stability and precision of the gear lock.

Pivot Structure: Most ergonomic chairs on the market use a bottom-pivot structure, where the pivot is hidden beneath the seat cushion. However, this structure is misaligned with the pivot point of the human hip joint, causing the lumbar support to detach from the lumbar spine when changing positions, resulting in increased fatigue for the user over time. Some ergonomic chairs, on the other hand, use a hip-pivot structure, such as the Flow Hip-Pivot Dynamic Lumbar Support System of the Yongyi Flow550. The armrests on both sides are connected by a single axis, and the position where the axis passes is aligned with the hip joint position when seated. The human hip joint and the chair's rotation axis form the same center, so when leaning back, the backrest and waist move together, and the relative displacement between the lumbar support and the back clothing is almost zero, greatly improving riding comfort.