The armrest and backrest height design of fabric multi-person sofa is a specific embodiment of ergonomics in the field of furniture. By fitting the skeleton and muscle state of the human body in a natural sitting posture, it can achieve reasonable support for various parts of the body, reduce the fatigue caused by sitting for a long time, and build comfort on a scientific structure.
The design of the armrest height first takes into account the natural placement needs of the arms. When a person is in a relaxed sitting posture, the arms will naturally droop, and the elbows will be bent at a certain angle. If the armrest height is flush with the elbow, the arm can completely fit the armrest surface, and the shoulder muscles do not need to deliberately exert force to maintain the arm posture, thus being in a relaxed state. If the armrest is too high, the arm will be lifted up, and the shoulder is prone to tightness; if it is too low, the arm lacks support and the shoulder needs to sink to accommodate, which will cause shoulder pain in the long run. Reasonable armrest height allows the arm to be placed naturally, which not only shares the weight of the upper body, but also avoids excessive tension of local muscles, reflecting the ergonomic considerations for upper limb relaxation.
The backrest height is closely related to the natural curve of the human spine. The spine has a natural physiological curvature from the cervical spine to the lumbar spine, and the backrest height needs to cover these curved parts to provide continuous support. The upper part needs to fit the cervical spine curve, the middle part corresponds to the thoracic spine, and the lower part supports the lumbar spine, so that the entire spine can maintain a natural stretch state, rather than being forced to straighten or bend. When a person leans back, the backrest can bear the weight of the back, disperse the pressure on the spine, and avoid discomfort in the waist and neck caused by excessive bending or stretching of the spine. This compliance with the natural shape of the spine is the core ergonomic embodiment of the backrest height design.
The layered design of the backrest height further refines the support for different parts. The upper area is for the head and neck. When people need a short break, the head can naturally lean on the upper part of the backrest, the neck muscles can be relaxed, and the cervical pressure caused by the head hanging in the air can be avoided; the middle area corresponds to the middle part of the back. Through appropriate convexity or curvature, it fits the back curve, enhances the contact area with the back, and disperses the pressure to a wider range; the lower part provides strong support for the lumbar spine, preventing the waist from collapsing backward due to lack of support, and maintaining the natural lordosis of the lumbar spine. This layered support allows all parts of the back to be supported accordingly, which conforms to the principle of "zonal support" in ergonomics.
The height and width of the armrests can also assist the body's sitting and getting up. When people get up from the fabric multi-person sofa, their arms will naturally press the armrests as a support point. The appropriate armrest height makes it easier for the arms to exert force, and the upper limbs can be used to drive the body to stand up, reducing the burden on the waist. Especially for people with limited mobility, this auxiliary role is more important. If the height of the armrest can match the force angle when getting up, the pressure on the joints of the action of getting up can be reduced, which reflects the consideration of human kinematics in furniture design, so that the function is not only static support, but also extends to the assistance of dynamic movements.
The coordination of the backrest height and the armrest height affects the sitting balance of the whole body. When the backrest height is enough to support the shoulders, and the armrest height matches the elbow, the center of gravity of the body will naturally fall between the sitting bones and the backrest, forming a stable support triangle. People can maintain balance without deliberately adjusting their posture, avoiding frequent movement of the body due to unstable center of gravity. This state of balance reduces the continuous fine-tuning of muscles, allowing the body to remain stable during long-term sitting, reducing energy consumption overall, and meeting the physiological needs of the human body in a relaxed state.
The inclination angle and height of the backrest are coordinated to further optimize the support effect. Reasonable height with appropriate inclination can maximize the contact area between the back and the backrest, while allowing the buttocks to have more sufficient contact with the seat surface of the fabric multi-person sofa, dispersing the body weight. For example, the upper part of the backrest is slightly tilted backward to accommodate the natural backward tilt of the head; the middle part maintains the arc that fits the curve of the back, and the lower part protrudes slightly forward to support the lumbar spine. This angle design combined with height allows each section of the spine to be supported accordingly to avoid discomfort caused by excessive pressure on a certain part.
The difference in height design under different usage scenarios also reflects the flexibility of ergonomics. The fabric multi-person sofa for daily leisure usually has a backrest height that covers above the shoulders, and the armrests are slightly higher, which is suitable for leaning on the whole body to relax, and you can even lean your head on the backrest to take a nap, at this time the neck and back can be supported; the fabric multi-person sofa that focuses on the guest function may have a slightly lower backrest height, and the armrest height is also adjusted accordingly, so that people can maintain a relatively correct sitting posture, which is convenient for communication but not too relaxed. This targeted height design allows the ergonomic characteristics of the fabric multi-person sofa to match the needs of the usage scenario, achieving a precise balance between function and comfort.
