When considering the posture motivation, the seats are basically divided into three categories: 1. 2. Working chairs in the workshop. 3. The multi-purpose chair
1.An easy chair for rest.
The design focuses on the human body to get the maximum comfort, to eliminate the body tension and fatigue. Reasonable design should minimize the pressure of the human body.
2. Working chairs in the workshop.
Stability is the main factor, the waist should have the proper support, the weight should be evenly distributed on the seat cushion (or seat surface), also should consider the human body's activity, the operation flexibility and the convenience.
3. Multi-purpose chair
This kind of chair is designed with a variety of functions. It may work with the table, it may be work, rest, or it can be folded up as a spare chair.
The study also showed that:
Using forward appropriate seat surface design work chair will be more suitable for work, especially the office work, such as for writing and drawing with the design of the chair, when demand is high, high for tilting drawing table with chairs, more than 15 degree Angle should reach before, if back Angle for 90. An Angle, with the back of a chair is equivalent to seat surface l05 degrees, this is the minimum comfortable sitting posture Angle, back of a chair for spinal department also can moderate support role, muscle tension is small, the back pressure distribution is uniform in vertebrae.
The height and width of the back.
Because the back of the body is in the natural form of the most comfortable, at this time the lumbar part is convex, the seat design should be from the Angle between the seat and the back of the back and proper lumbar support to try to ensure. The center of the lumbar spine of adults is about 23 to 26cm above the seat, and the lumbar spine should be slightly higher than that to support the back weight. The backrest is made up of two parts, shoulder and waist, most of the work place, the waist is the most important. The maximum height of the backrest can reach 48-63cm and the maximum width can reach 35-48cm. The size of the backrest mainly depends on the height of the bottom of the hip to the shoulder (the height of the back is high) and the shoulder width (determine the back width), and the height must also be included in the effective thickness of the seat.
In order to make the lower back of the sacrum and buttocks properly posterior convex space, there should be a concave or open portion between the upper part of the seat and the lower part of the back, and the height is at least 12.5 to 20cm. Angle of backrest: 10112-degree armrest height: the effective thickness of the seat cushion is 21 to 22cm. In case of some pending operation, the general seat should consider setting the handrail. The main function of the handrail is to make the arm to rely on, reduce the function of the arm droop gravity to the shoulder, make the human body is in a more stable state. It can also serve as a starting point for standing up or changing your posture. The armrest should not be too high, otherwise it will force the elbow to lift and stretch the shoulders and neck muscles. However, if too low, the arm can not be supported, or the trunk must be deflected to seek support on one side.
Human body in sitting position state, close contact with the seat surface of two ischial tuberosity is actually the hips, it is only a small amount of muscle, and about 75% of the weight by about 25 cm2 sciatic around the site to support, so sedentary fatigue, enough to produce pressure lead to hip pain numbness. According to the test results, the hip pressure value of the seat cushion is greatly reduced, and the contact support area is also increased from 900cm2 to 1050cm2, so that the pressure is dispersed. Its structural material should be durable, flame retardant, non-toxic. Cushions, waists and armrests should be made of soft, skidproof, breathable and sweat-absorbent non-conductive materials.