What kind of chair is the most comfortable?
Let's first understand the sitting habits of people.
People's sitting posture can be roughly divided into three types: sitting forward, sitting straight, leaning back. The posture of sitting forward is mainly the posture of work, and the posture of leaning back is the posture of rest and relaxation. When the person sits forward, the human pelvis rotates into a tilted state, and the tibia also moves accordingly, and tends to level, flattening the tibia and lumbar vertebrae, causing the spine to become a kyphosis above the waist, which looks like a hunchback, sitting straight. At the time, the pelvis is erect, the position of the tibia is also relatively vertical, and the lordosis of the spine is formed at the lumbar vertebrae.
By analyzing the physiological characteristics of people in sitting position, we can use these features to derive the most comfortable design size of the chair. When the design of the chair maximizes ergonomics, the comfort of the chair is maximized.
So how do you design a chair based on ergonomic principles? We will interpret the chair size standards for mahogany furniture.
First, sit high
Sitting height refers to the vertical distance from the seat to the ground. Since the seat surface is often inclined backwards, the seat height of the chair is usually the height of the seat as the seat height of the chair. If the seat surface is inclined backward or concave, the seat height is the vertical distance from the center of the front seat to the ground.
Appropriate seating height: Keep the thighs level, the calves vertical, and the feet flat on the ground. If the seat height is too high, the two legs will vacate the thigh blood vessels. If it is too low, it will cause physical fatigue. Practice has proved that the appropriate seat height is the calf height to the sole height plus the heel thickness of 25mm-35mm, and then the activity margin of 10mm-20mm is subtracted.
Namely: sitting height = calf height + heel thickness - appropriate clearance.
National standard GB 3326-1997 specifies: sitting height is 400mm-440mm, size difference is 10mm
Second, sit deep
Sitting depth refers to the distance from the front to the back of the chair. The sitting depth has a great influence on the comfort of the sitting posture. If the chair is deeper than the horizontal length of the thigh, the backrest of the human body will have a large inclination, and the waist will be suspended without a support point, which will aggravate the muscle activity of the waist and cause fatigue. At the same time, the seat is too deep, so that the knee is at the knee Produces numbness and is also not conducive to standing up.
The average length of the thigh in China's sitting posture is 445mm for males and 425mm for females. Then, there is a certain distance (about 60mm) from the inside of the knees in front of the sitting, so that the sitting depth is generally between 380mm and 420mm.
Third, sitting width
The width of the seat surface of the chair is usually in the shape of a front width and a narrow shape according to the sitting posture and movement of the person. The width of the front edge of the seat surface is called the front width, and the width of the rear edge is called the back width.
The seat width is generally not less than 380mm. For a chair with armrests, it is necessary to consider the support of the human arm. The inner width of the armrest is used as the seat width, and an appropriate margin is added according to the average shoulder width of the human body. Not less than 460mm, but not too wide, should be based on the comfortable shoulder width of the natural vertical arm.
Fourth, the slope of the sitting surface
When the person is resting, the sitting posture is leaning backwards to support the lumbar vertebrae, so most of the general sitting faces are designed to be inclined backward. The inclination of the seat surface is generally 3 to 5 degrees, and the opposite seat back is also inclined backward.
Fifth, the height of the backrest
The size of the backrest is mainly related to the height from the bottom of the buttocks to the shoulders (determining the height of the backrest) and the width of the shoulders (determining the width of the backrest). The height and width of the backrest of the chair, the maximum height of the backrest can reach 480mm~ 630mm, and the maximum width can reach 350mm~480mm.
Sixth, armrest height
The height of the armrest should be similar to the vertical distance from the human ischial node to the lower end of the elbow when it is naturally drooping. Practice has proved that the vertical distance from the upper surface of the armrest to the seat surface is preferably 200mm-250mm. At the same time, the front end of the handrail should be slightly higher. With the change of the inclination angle of the seat surface and the angle of the backrest, the inclination of the handrail is generally 10 degrees-20 degrees, and the handrail is preferably within 10 degrees of the horizontal left and right angle side.
All in all, the size of the furniture is based on the human scale, and only the size of the furniture is more comfortable. The chair is generally used with the table. Therefore, the height of the table is closely related to the height of the chair and the scale of the human body. The height of the table and the height of the chair are matched. If the height of the table is high and the height of the chair is relatively low, then sit on it. It is more tired, the arm should be raised very high. On the contrary, the table is low and the chair is high. People sit on the chair and work at the desk. The waist will be very hard, so it is very important to have a reasonable match.