JP7770001B2 - Functional chairs and functional floor chairs - Google Patents

Description

The present invention relates to a chair that is ergonomically designed to prevent straight neck and maintain a healthy neck posture (hereinafter referred to as healthy neck posture) when using desktop or portable computer equipment or reading.

In today's digital society, opportunities to access information using desktop or portable computer devices have become increasingly common. Here, desktop or portable computer devices refer to personal computers, game consoles that use displays, and portable game consoles, as well as smartphones and tablet personal digital assistants (hereinafter, "smartphones or tablets" will be referred to as "smartphones, etc."). Furthermore, by downloading game apps (a general term for application software classified as games) developed for mobile devices, it is possible to play games on the display of the computer device. Traditionally, when working on a VDT (visual display terminal) while sitting in a chair and operating desktop computer equipment, protruding the head while working continuously has been a problem, as it places strain on the spine.

In recent years, the development of mobile information devices such as smartphones has made it possible for anyone to access any information or enjoy games at any time, anywhere.

At the same time, the health effects of prolonged use of smartphones and other devices are becoming a concern. When using smartphones and other devices, people often operate them while standing or while sitting on a stool or chair. In doing so, they hold the device in front of their body. To operate the device without tiring their arms, they typically operate the device by lowering their upper arms vertically and holding only their forearms horizontally, or by resting their elbows on their knees, leaning forward from their upper body to their neck, and looking diagonally downward (hereinafter referred to as the "head-down posture"). A head-down posture tends to cause the neck to be thrust forward, which can lead to the modern disease of straight neck. According to a preventive medical model study conducted by the Japan Institute of Occupational Health and Safety, an independent administrative institution under the jurisdiction of the Ministry of Health, Labor and Welfare, using smartphones and other devices tends to result in a head-down posture compared to using a personal computer. Research has shown that a healthy neck posture when using a computer involves an average forward tilt of the neck of 23±13 degrees, but when using a smartphone or other device while standing, the average forward tilt of the neck is 37±14 degrees, indicating a greater degree of head tilt. The forward tilt angle of the neck is the same angle formed between the line of sight when the forward tilt angle of the neck is 0 degrees and the line of sight when looking straight ahead while in a head tilted position. In this specification, this angle is referred to as the head depression angle. In this case, the load of the head's weight on the cervical vertebrae doubles if the head is pushed forward by just 2 cm, and five times if the head is pushed forward by 4 cm; it has been reported that if this condition continues for a long period of time, it can lead to a condition known as a straight neck.

Straight neck occurs when strain is placed on the normally gently curved cervical vertebrae by maintaining a hunched posture, causing the curve to be lost and the head to become chronically protruding forward. The gentle curve of the cervical vertebrae distributes the strain from the weight of the head across the neck and shoulders, but when you develop straight neck, the strain on the neck and shoulders increases, leading not only to stiff shoulders and neck, but also to headaches and dizziness. In today's digital society, where the use of VDT equipment is the norm, it is said that many smartphone and other device users, regardless of age or gender, suffer from straight neck.

Not only when using smartphones, but also when using a computer at a desk for long periods of time, eye fatigue can cause people to get too close to the display, which can make it difficult to see, or the display can be positioned so that the gaze is directed significantly downward rather than horizontal, causing the neck to be thrust forward, which can lead to stiff neck. Musculoskeletal symptoms, including stiff neck, caused by using information device displays, as well as symptoms such as eye fatigue, and other symptoms that affect the whole body and mind, are collectively referred to as VDT syndrome.

Straight neck can be prevented by keeping your back straight, holding your smartphone or other device at eye level, and looking at the display with a small angle of depression, which will allow you to maintain a healthy neck posture without thrusting your neck forward.

As a prior art technique for correcting posture, Patent Document 1 discloses a chair that has a back support portion on the backrest surface that supports the user 's thoracic-lumbar junction area, making it possible to stabilize posture by limiting the contact area between the backrest surface and the user's back to around the thoracic-lumbar junction area.

Patent Document 2 also discloses a chair in which the armrests are provided with support for the upper arms and elbows, allowing the elbows to be placed on the armrests and the forearms to be lifted when performing tasks such as typing on a computer keyboard or using a mouse. This allows for greater freedom of movement for the forearms than conventional methods of placing the forearms on the armrests, thereby improving workability.

Japanese Patent Application Laid-Open No. 2017-94015 Japanese Patent Application Laid-Open No. 2002-78562

Straight neck, which develops from using a smartphone or other device, is caused by fatigue in the hands and arms holding the smartphone, which lowers the height of the device, increasing the angle of depression and causing the neck to protrude forward, and cannot be prevented by simply correcting the spine. Considering the mechanism of the onset of straight neck, it is difficult to prevent the onset of straight neck with a chair that only has a function to correct the spine, as in Patent Document 1.

Patent Document 2 discloses that floating the forearms improves workability and allows the elbows to rest on the armrests, thereby relaxing the arms. While typing on a computer keyboard or using a mouse is certainly done on a desk, reducing arm fatigue, when using a smartphone or similar device, it is necessary to raise the elbows even higher and hold the smartphone or similar device with the hands raised until the angle of depression when looking at the display is within 23 degrees ±13 degrees. The armrest height of the chair disclosed in Patent Document 2 is not designed for use with smartphones or similar devices, so raising the hands to a height that allows the gaze to be horizontal toward the display results in the elbows floating in the air. This increases fatigue throughout the arms, causing the position of the hands to drop over time, which induces a downward posture and can lead to the development of a straight neck.

Even when using a personal computer, with a laptop computer the display and keyboard are integrated, so the display is low and the depression angle is large, making it impossible to prevent the onset of straight neck.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a functional chair that is ergonomically designed to correct the hunched posture when using desktop or portable computer equipment or reading, and to reduce fatigue in the hands and arms when holding computer equipment or books, thereby preventing the onset of straight neck. In particular, the aim is to provide a functional chair that is effective when using smartphones or other devices that do not require a desk, or when reading.

In order to solve the above problems, the functional chair of the present invention is a functional chair that is used when using desktop or portable computer equipment and has at least a seat, a backrest, and armrests, characterized in that the backrest is formed at a height that supports the user's buttocks to at least the neck, the angle between the seat and the backrest is obtuse, the area above the top of the shoulder blades is inclined toward the user and has a gentle curve that continues in the height direction, and the height of the upper surface of the armrests is 300 mm to 400 mm from the seat . A sagittal plane refers to a plane that cuts the user symmetrically and a plane parallel to that plane.

Furthermore, the functional chair of the present invention is a functional chair that has at least a seat, a backrest, and armrests for use when using desktop or portable computer equipment, characterized in that the backrest is formed at a height that supports at least the user's neck with an obtuse angle between the seat and the backrest, has a recess with a symmetrical shape in the center of the top surface of the backrest, and the height of the top surface of the armrests is 300 mm or more and 400 mm or less from the seat.

The functional chair of the present invention as set forth in claim 1 or claim 2 is characterized in that the backrest is integrally formed.

Furthermore, the functional chair of the present invention described in claim 1 or claim 2 is characterized in that the backrest extends integrally, forming a continuous, gentle recess in the central vertical axis direction from the rear lower end of the armrests on both sides to the neck area, and the narrowest point of the recess is narrower than the width of the seat surface.

Furthermore, the functional chair of the present invention described in claim 1 or claim 2 is characterized in that the distance between the armrests on both sides gradually and continuously expands from the upper end of the armrest toward the connection with the seat.

Furthermore, the functional chair of the present invention described in claim 1 or claim 2 is characterized in that the obtuse angle is set to 100 degrees to 110 degrees.

According to the functional chair of the present invention, when a user sits and rests their elbows on the armrests to look at a smartphone or book held in both hands, the armrests are set at a height such that, when viewed from the side of the body, the angle formed by the upper arm and a vertical line passing through the acromion point is greater than 0 degrees and less than 90 degrees. This inevitably allows the user to position the smartphone or book held in both hands at a depression angle of 10 degrees to 36 degrees, thereby preventing a hunched posture and preventing the onset of straight neck caused by maintaining a hunched posture for long periods of time. The acromion point is the outermost point of the acromion of the scapula.

Furthermore, with the functional chair of the present invention, by fixing the elbows at a high position, the upper body is supported by the upper arms with the shoulders (acromion point) as the fulcrum, and it is not possible to tilt the head any lower. This naturally opens the chest and closes the shoulder blades, allowing the buttocks, spine, and shoulder blades to come into contact with the backrest, resulting in the spine forming a natural S-curve and maintaining a healthy neck posture. In other words, as long as a person is seated in the functional chair of the present invention with their back in contact with the backrest and their elbows resting on the armrests, a healthy neck posture is maintained and prevented from collapsing when using a smartphone, etc.

When holding a smartphone or other device with both hands with its length horizontal, the wider the distance between the armrests, the more difficult it is to rest your elbows on the armrests unless you extend both elbows out to the side. In this case, the height of the smartphone or other device becomes lower, so in order to maintain a healthy neck posture, you have to move your elbows away from the armrests and raise your hands higher, which causes arm fatigue. With the functional chair of the present invention, by setting the distance between the buttocks wide and narrowing the distance between the tops of the armrests, users with narrow elbow spacing can rest their elbows on the armrests, achieving the effect of positioning a smartphone or other device within the depression angle that is considered a healthy neck posture. It also prevents users with narrow elbow spacing from lowering their elbows to the inside of the armrests instead of resting them on the armrests.

On the other hand, when a user is seated, the seated hip width is usually wider than the horizontal diameter of the torso. The seated hip width is the maximum horizontal diameter of the buttocks measured perpendicular to the sagittal plane. With the functional chair of the present invention, the armrests gradually expand from the tops of the arms toward the points where they connect to the seat, allowing the user to sit comfortably without feeling cramped in the buttocks.

1 is a perspective view of a functional chair 10 according to the present invention. 1 is a diagram showing a state in which the functional chair 10 according to the present invention is used. FIG. 10 is a diagram showing the optimal position for operating ME such as a smartphone while sitting in a chair. 1 is a side view of a functional chair 10 according to the present invention. 1 is a front view of a functional chair 10 according to the present invention. This figure shows the optimal height of the armrest when the acromion height in the sitting position, upper arm length, forearm length, and medial canthus height in the sitting position are at their maximum values in the physical data. This is a diagram showing the optimal height of the armrest 12 when the acromion height in a sitting position, upper arm length, forearm length, and medial canthus height in a sitting position are at their minimum values in the physical data. This figure shows the state when the height of the armrest 12 is 330 mm when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position of a young adult are average values. This figure shows the range of optimal heights for the armrest 12 when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position of a young adult are average values. This figure shows the state in which the height of the armrest 12 is 330 mm when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position of an elderly person are average values. This figure shows the range of optimal heights for the armrest 12 when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position of an elderly person are average values. This figure shows the optimal height of armrests 12 when using a desktop computer at a computer desk for young adults with average values for acromion height, upper arm length, forearm length, and medial canthus height in a sitting position. This figure shows the optimum height of the armrest 12 when using a laptop computer at a computer desk, for a young adult with average values for acromion height, upper arm length, forearm length, and medial canthus height in a sitting position. This figure shows the optimal height of the armrest 12 when using a desktop PC at a computer desk for elderly people whose acromion height, upper arm length, forearm length, and medial canthus height in a sitting position are average values. This figure shows the optimal height of the armrest 12 when using a laptop computer at a computer desk for elderly people whose acromion height, upper arm length, forearm length, and medial canthus height in a sitting position are average values. 1 is a perspective view of a chair 20 according to the present invention. FIG. 10 is a diagram showing a typical chair 81 without armrests in use. 1 is a diagram showing a typical armchair 80 in use. This is a diagram showing the positional relationship between various body parts and armrests 82 when a person with average physical data of a young adult is seated in a typical armchair 80. This is a diagram showing the positional relationship between various body parts and armrests 82 when a person with average physical data of an elderly person is seated in a typical armchair 80.

An embodiment of the functional chair 10 of the present invention will be described with reference to the drawings. Figure 1 is a perspective view of the functional chair 10 of the present invention. The functional chair 10 is intended for use when using desktop or portable computer equipment. In particular, when using ME such as smartphones, which are frequently used in modern society, it is possible to maintain a healthy posture of the neck 53 and effectively prevent straight neck. The functional chair 10 comprises at least a seat 16, a backrest 14, and armrests 12, but Figure 1 shows the functional chair 10 with legs 18.

Figure 2 shows the functional chair 10 of the present invention in use. The armrests 12 are shaped so that when a user 50 is seated with their buttocks 60 and back 58 in contact with the backrest 14 and their elbows 56 resting against the armrests 12, and they are facing a smartphone or other ME held in both hands and looking directly at it, the angle formed by the upper arm 55 and a vertical line passing through the acromion 54 in a lateral view is greater than 0 degrees and less than 90 degrees forward (see also Figure 3). That is, the height from the seat surface 16 to the top surface of the armrest 12 is set higher than that of a typical chair, and the distance from the acromion 54 to the top surface of the armrest 12 is shorter than the length of the upper arm, so that the position where the elbows 56 are placed on the armrests 12 is not further back than the side of the user's 50 body. Furthermore, by placing the elbow 56 as far forward as possible on the armrest 12, the smartphone or other ME can be placed at a height close to the eye 52 level, so instead of a hunched posture, the spine 59 forms a natural S-curve, allowing the neck 53 to be maintained in a healthy position.

First, we will examine healthy posture for the neck when using a smartphone or other ME while seated in a chair. Figures 15 and 16 show postures when using a smartphone or other ME while seated in a typical chair. Figure 15 shows the state of use in a typical chair 81 without armrests. Because there is no stable place to rest the elbows 56, the person inevitably assumes a hunched, bowed posture, causing the spine 59 to curve like an arch. When the hands holding the smartphone or other ME become tired, the position of the smartphone or other ME moves further downward, such as by resting the elbows 56 on the thighs, further increasing the bowed posture and the degree of curvature of the spine 59.

Figure 16 shows a typical armchair 80 in use. The standard desk height for a computer desk is approximately 700 mm. A computer desk is a desk used for operating tabletop computer equipment, and is used for office work, hobby work, entertainment using electronic devices, competitions, and general sports, including so-called e-sports. Desks for other purposes are often lower than computer desks. To use a chair with armrests 82 with these desks, the armrests 82 are typically set at a height that fits underneath the desk top DS so as not to interfere with it. Therefore, the height from the seat 86, which has a standard height of 400 mm, to the armrests 82 is generally 230 mm or less, subtracting the typical thickness of the desk top DS, which is 70 mm. In this case, for a person with average body dimensions, when the elbows 56 are lowered on a vertical line passing through the acromion point 54 with an upright back, i.e., when the elbows 56 are lowered directly from the shoulders, they will not reach the armrests 82.

Figure 17a is a diagram showing the positional relationship between various body parts and armrests 82 when a person with average physical data of a young adult is seated in a typical armchair 80. Figure 17b is a diagram showing the positional relationship between various body parts and armrests 82 when a person with average physical data of an elderly person is seated in a typical armchair 80.

The physical data used was the human body size database published by the National Institute of Advanced Industrial Science and Technology (National Institute of Advanced Industrial Science and Technology AIST Human Body Size Database 1991-92) published by the Artificial Intelligence Research Center. The dimensions required to derive healthy neck postures when using desktop or portable computer equipment are shown in Table 1.

The acromion height in the sitting position is the height from the seat surface to the acromion point. The medial canthus height in the sitting position is the height from the seat surface to the medial canthus point. The upper arm length is the linear distance from the acromion point to the radial point, i.e., the distance from the shoulder to the elbow along the upper arm. The radial point is the highest point on the superior edge of the radial head when the upper limb is naturally hanging down. The olecranon-to-grip axis distance is the horizontal distance from the posterior edge of the olecranon to the center of the clenched hand. The olecranon-to-grip axis distance is approximately the same length as the length of the forearm 57 (forearm length). The elbow span is the maximum horizontal diameter between the lateral surfaces of the left and right elbows measured perpendicular to the sagittal plane. The hip width is the horizontal diameter of the waist measured perpendicular to the sagittal plane at the widest point of the waist when viewed from the front. Explanations of body-related terms used in this specification are taken from the human body measurement database published by the Artificial Intelligence Research Center of the National Institute of Advanced Industrial Science and Technology.

When the angle between the seat surface 86 and the backrest 84 is 115 degrees, i.e., when the angle of the backrest 84 from the horizontal plane is a typical 75 degrees, in order to view a smartphone or other ME, the center line from the chest to the head 51 is usually raised so that it faces vertically. If the upper body is reclined at the same angle as the backrest 84, the smartphone or other ME must be raised higher than the height of the eyes 52, which causes fatigue to accumulate in the arms.

In Figures 17a and 17b, the upper arm length is shorter than the distance from the acromion point 54 to the armrest, and when the user 50 is seated with their back 58 from their buttocks 60 in contact with the backrest 84 and their spine straight, and looks roughly directly at an ME such as a smartphone held in both hands, their elbows 56 do not reach the armrest 82.

If you continue to use a smartphone or other ME in this state, as shown in Figure 16, you will bend your body forward, place your elbows 56 on the armrests 82, and look at the display DP with your head down, causing your spine 59 to curve like an arch. Therefore, if you use a smartphone or other ME while sitting in a regular chair without resting your arms on the desk, you are very likely to develop straight neck.

The healthy posture for the neck when using a smartphone or other electronic device while seated in a chair will be explained with reference to Figure 3. Figure 3 is a schematic diagram of the seated state in Figure 2, excluding the chair. As mentioned above, when leaning the back 58 against the chair back 14, in order to view a smartphone, the center line from the chest to the head 51 is typically raised so that it faces vertically. The healthy posture for the neck 53 when using a computer while seated in a chair is the aforementioned depression angle of 23±13 degrees. Applying this to Figure 3, the range of depression angles for a healthy posture for the neck 53 is a 36-degree rotation from a position rotated 10 degrees counterclockwise from the horizontal direction at eye height 52. This range will also be used as the range for a healthy posture for the neck 53 when using a smartphone or other electronic device.

The distance between the smartphone or other ME and the eyes 52 needs to be approximately 300 mm for the health of the eyes 52, so it is clear that the elbows 56 need to be positioned considerably higher than the seat surface. If the elbows 56 are on a vertical line drawn from the acromion point 54, it is clearly difficult to position the smartphone or other ME within a depression angle range of 23±13 degrees.

The eye 52 can move its line of sight up and down without changing the angle of the neck. The eyeball has a field of view of approximately 120 degrees, meaning it can see without moving. However, there are portions of approximately 30 degrees at the top and bottom that cannot be accurately seen. Taking all of this into consideration, the entire smartphone or other ME does not need to be within the hatched area in Figure 3; as long as the center of the smartphone or other ME is on the boundary line, it is possible to maintain a depression angle within the range of 23±13 degrees and see everything displayed on the display DP.

4 is a side view of the functional chair 10 according to the present invention. The backrest 14 is set at a height that supports the user's 50 hips 60 to at least the neck 53. The angle between the seat 16 and the backrest 14 is obtuse, and the backrest 14 is inclined toward the user 50 above the upper shoulder blades, forming a gently curved shape in the height direction. The angle of the backrest 14 from the hips 60 to the back 58 is set to 100 to 110 degrees, similar to the angle of the backrest 14 of a typical computer chair, i.e., the angle of the backrest 14 from the hips 60 to the back 58 is set to 70 to 80 degrees from the horizontal. Since the centerline of the backrest 14 above the upper shoulder blades is normally vertical, as mentioned above, the backrest 14 is inclined toward the user 50, approximately ±5 degrees from the vertical, to fit the upper body. The shape of the backrest 14 reduces fatigue when sitting for long periods of time and using a smartphone or other ME. On the other hand, when using a smartphone or other ME, the height from the seat surface 16 to the top of the armrest 12 is an especially important condition, which will be described in detail later.

FIG. 5 is a front view of a functional chair 10 according to the present invention. The spacing between the armrests 12 on both sides gradually widens from their tops toward the connection points with the seat surface 16. As an example, the spacing between the top ends of the armrests 12 is set to 380 mm, shorter than the average elbow-to-elbow width of a user 50, which is 400 mm (see Table 1). This is because if the spacing between the armrests is too wide, the user 50 will lower their elbows 56 without resting them on the armrests. The longitudinal dimension of current smartphones is approximately 100 mm to 150 mm. Therefore, when a smartphone is held with both hands with its longitudinal direction horizontal, resting the elbows 56 on both armrests will result in both elbows 56 protruding sideways. In this case, the wider the spacing between the armrests, the more the user must protrude both elbows 56 sideways to rest them on the armrests, forcing the hands holding the smartphone to move downward. In this case, the gaze is forced to be significantly lowered downward from the horizontal, increasing the angle of depression and resulting in a hunched posture that can lead to a straight neck. To maintain a healthy neck posture when using a smartphone, the user must move their elbows 56 away from the armrests, causing fatigue in the arms. According to the functional chair 10 of the present invention, by setting the armrests 12 at the waist farther apart and narrowing the distance between the tops of the armrests 12, users 50 with narrow elbow spacing can place their elbows 56 on the armrests 12 with less sideways movement, allowing them to position the smartphone within the angle of depression considered healthy for the neck when using a smartphone or other ME. Furthermore, this prevents users 50 with narrow elbow spacing from lowering their elbows 56 toward the inside of the armrests 12 rather than placing them on the armrests 12. Meanwhile, the average hip width in a seated position is approximately 340 mm (see Table 1), with a maximum value of 413 mm. To allow users 50 of all sizes to sit comfortably, the distance between the armrests 12 and the seat 16 is set to 430 mm, for example. The functional chair 10 according to the present invention is suitable for users 50 with extremely large body sizes and small children 50, as long as it has a function that allows the distance between the armrests 12 to be widened or narrowed according to the user's size. The above-described distance between the upper ends of the armrests 12 and the distance between the armrests 12 and the seat 16 are merely examples, and are not limited thereto. It is sufficient to narrow the distance between the upper ends of the armrests 12 so that the elbows 56 do not hang down from the armrests 12, and to widen the distance between the lower ends of the armrests 12 from the upper ends so that the buttocks 60 do not feel cramped.

When using a smartphone or other ME while seated in a chair, the height from the seat surface 16 to the top of the armrest 12 is an important condition for maintaining a head depression angle within the range of 23±13 degrees, which is considered to be a healthy posture for the neck. The following is a study to determine the height from the seat surface 16 to the top of the armrest 12 (hereinafter, "height from the seat surface to the top of the armrest" will be referred to as "armrest height").

First, using body data, the optimal armrest height was confirmed when the seated acromion height, upper arm length, forearm length, and seated medial canthus height were at their maximum and minimum values. Figure 6 shows the optimal armrest height when the seated acromion height, upper arm length, forearm length, and seated medial canthus height were at their maximum values. When the seated acromion height, upper arm length, forearm length, and seated medial canthus height data are at their maximum values, it can be seen that the height of the armrest 12 should be between 330 mm and 450 mm inclusive in order to tilt the gaze slightly downward and maintain a depression angle within a range of 23±13 degrees. The eyes 52 can be moved up and down without changing the angle of the neck 53. The subject also has a visual field of approximately 120 degrees. Therefore, the entire smartphone or other ME does not need to be positioned at an angle of 10 degrees or more and 36 degrees or less counterclockwise from the horizontal direction centered on the eye 52; as long as the center of the smartphone or other ME is on the boundary line, the depression angle can be maintained within the range of 23±13 degrees, making it possible to view the entire display DP.

7 is a diagram showing the optimal height of the armrest 12 when the acromion height, upper arm length, forearm length, and medial canthus height in the seated position are at their minimum values, using body data. When the data for acromion height, upper arm length, forearm length, and medial canthus height in the seated position are at their minimum values, the armrest 12 height should be within the range of 230 mm to 330 mm in order to tilt the gaze slightly downward and maintain the depression angle within the range of 23±13 degrees. As mentioned above, the entire ME, such as a smartphone, does not need to be positioned at an angle of 10 degrees to 36 degrees counterclockwise from the horizontal direction centered on the eye 52.

When the acromion height in the seated position, upper arm length, forearm length, and medial canthus height in the seated position are at their maximum and minimum values, the common armrest 12 height is 330 mm, which is found to be the optimal value.

Furthermore, we confirmed the height of the armrest 12 that can maintain a healthy neck posture when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position are average values. The average values of the human body dimension data published by the Artificial Intelligence Research Center of the National Institute of Advanced Industrial Science and Technology are shown for young adults and elderly people, so we examined them separately. Figure 8 shows the armrest 12 at a height of 330 mm when the acromion height, upper arm length, forearm length, and medial canthus height in a sitting position for a young adult are average values. It can be seen that a smartphone or other ME is positioned sufficiently within a depression angle range of 23±13 degrees.

Next, using the average values of the physical data of young adults, we confirmed the height of the armrest 12 that would allow a smartphone or other ME to be positioned within a depression angle range of 23±13 degrees. Figure 9 is a diagram showing the range of optimal armrest 12 heights when young adults' acromion height, upper arm length, forearm length, and medial canthus height in a seated position are average values. It can be seen that in order to position and maintain a smartphone or other ME within a depression angle range of 23±13 degrees, the height of the armrest 12 should be within the range of 307 mm to 440 mm.

Next, we confirmed the optimal height of the armrest 12 for the average physical data of elderly people. First, Figure 10 shows the state when the armrest 12 is set to a height of 330 mm when the acromion height, upper arm length, forearm length, and medial canthus height in a seated position of an elderly person are at their average values. It can be seen that ME devices such as smartphones are positioned within a depression angle range of 23±13 degrees.

Next, we confirmed the height of the armrest 12 that allows a smartphone or other ME to be positioned within a depression angle range of 23±13 degrees, based on the average physical data of elderly people. Figure 11 is a diagram showing the range of optimal armrest 12 heights for elderly people with average values for acromion height, upper arm length, forearm length, and medial canthus height in a sitting position. It can be seen that in order to position and maintain a smartphone or other ME within a depression angle range of 23±13 degrees, the height of the armrest 12 should be between 275 mm and 390 mm.

We consider both young adults and elderly people. The range of armrest 12 heights that can maintain a healthy neck posture for young adults is 307 mm to 440 mm. The range of armrest 12 heights that can maintain a healthy neck posture for elderly people is 275 mm to 390 mm. Of both ranges, the common range of 307 mm to 390 mm is found to be the preferred range for armrest 12 heights that can be applied to both young adults and elderly people. Furthermore, the eyes 52 can move their gaze up and down without changing the angle of the neck 53. Furthermore, since the field of view is approximately 120 degrees, the armrest 12 height that can maintain a depression angle of 23 ± 13 degrees, considered a healthy neck posture, can be expanded by approximately 10 mm to 300 mm to 400 mm.

Figure 12a shows the optimal height of the armrest 12 when using a desktop computer at a computer desk for a young adult with average values for acromion height, upper arm length, forearm length, and medial canthus height. Generally, the seat height from the floor when using desktop computer equipment is set to approximately 360 mm to 450 mm, with an average of 400 mm. The height of the top surface of the computer desk's top plate (DS), including those equipped with height adjusters on the bottom of the legs, is set to approximately 650 mm to 750 mm, with an average of 700 mm. The functional chair 10 of the present invention, with an armrest 12 set to a height of 330 mm, was applied to this computer desk for study. The height of the armrest 12 is approximately 30 mm higher than the computer desk top plate (DS). When the palm of the hand is placed on the computer desk top plate (DS), the thickness of the palm allows the fingers to approach the keyboard (KB) horizontally, reducing fatigue even during extended use.

If the display DP is positioned so that its center is tilted 23 degrees counterclockwise from horizontal with the eye 52 at its center, and the distance between the eye 52 and the display DP is at least 400 mm for a standard display DP, or at least 500 mm for a widescreen display, which is generally considered appropriate, the elbow 56 will be positioned forward of the body as shown in the figure. In this case, the head 51 will be difficult to move forward because the elbow 56 is placed on the armrest 12 and the upper body is supported by the upper arm 55, with the shoulder as the fulcrum. If the elbow 56 is moved forward, the shoulder will move forward and the head 51 will move forward, resulting in a hunched posture. However, at the same time, the fingers will also move forward, making it impossible to type. Therefore, the elbow 56 cannot be extended forward. It is also possible to shrug the shoulders and thrust the upper body forward to assume a hunched posture, but this becomes very uncomfortable and makes it difficult to maintain the same posture for long periods of time. Therefore, the depression angle can be maintained within a range of 23±13 degrees, preventing the patient from assuming a hunched posture and maintaining a healthy neck posture.

Figure 12b shows the optimal height of the armrest 12 when using a laptop computer at a computer desk for a young adult with average values for acromion height, upper arm length, forearm length, and medial canthus height. As in Figure 12a, the height of the armrest 12 was set to 330 mm. Because the display DP of a laptop computer is connected to the keyboard KB, the display DP must be lower than that of a desktop computer, causing the operator to tilt their head down more. However, Figure 12b shows that the display DP can be positioned within a depression angle of 23±13 degrees. The height of the armrest 12 in this embodiment is merely an example; the same effect can be achieved by setting the armrest 12 at a height that allows the elbows 56 to extend forward from the sides of the body.

Figure 13a shows the range of optimal armrest heights (12) when using a computer desk for an elderly person with average values for acromion height, upper arm length, forearm length, and medial canthus height (sitting position). The computer desk is as described above. The functional chair 10 of the present invention, with the armrest 12 set to a height of 330 mm, was applied to the computer desk. The height of the armrest 12 is approximately 30 mm higher than the computer desk top DS. When the palm of the hand is placed on the computer desk top DS, the thickness of the palm allows the fingers to approach the keyboard KB horizontally, just like a young adult. The difference is that the keyboard KB is moved slightly closer to the body due to differences in upper arm and forearm length.

If the display DP is positioned so that its center is tilted 23 degrees counterclockwise from horizontal with the eye 52 as the center point, and the distance between the eye 52 and the display DP is kept within the generally accepted range, the elbow 56 will be positioned forward from the side of the body, as shown in the figure. In this case, the person places their elbow 56 on the armrest 12, just like a young adult, and supports their upper body with their shoulder as a fulcrum using their upper arm 55, making it difficult for the head 51 to move forward. If the elbow 56 is moved forward, the shoulder moves forward and the head 51 moves forward, resulting in a bowed posture. However, at the same time, the fingers also move forward, preventing keyboard input, making it impossible to move the elbow 56 forward. It is also possible to thrust the upper body forward by shrugging the shoulders and bowing, but this is very uncomfortable and makes it difficult to maintain the same posture for long periods of time. Therefore, the bow angle can be maintained within a range of 23±13 degrees, preventing bowed posture and maintaining a healthy neck posture.

Figure 13b shows the optimal height of the armrest 12 when using a laptop computer at a computer desk for elderly people with average values for acromion height, upper arm length, forearm length, and medial canthus height in a seated position. As in Figure 13a, the height of the armrest 12 was set to 330 mm. Because the display DP of a laptop computer is connected to the keyboard KB, the display DP must be lower than that of a desktop computer, causing the operator to tilt their head down more. However, Figure 13b shows that the display DP can be positioned within a depression angle range of 23±13 degrees. The height of the armrest 12 in this embodiment is an example, and the same effect can be achieved if it is set at a height that causes the elbows 56 to extend forward from the sides of the body.

Figure 14 is a perspective view of the seat 20 of the present invention. It has no legs, allowing it to be used in a Japanese-style room. In a Japanese-style room, the user can stretch out their legs and move their buttocks 60 forward. However, the seat 20 of the present invention is preferably set to a height of 300 mm to 400 mm from the seat surface 26 to the top of the armrest 22. Because this height is set higher than that of a typical chair, the position of the acromion point 54 is lowered. If it is lower than the height of the armrest 22, the angle formed by the upper arm 55 and the vertical line passing through the acromion point 54 exceeds 90 degrees. This means that the smartphone or other ME is positioned higher than the eye 52 by the length of the forearm, causing the gaze to be directed diagonally upward from the horizontal, resulting in significant fatigue. Therefore, the user naturally sits with the buttocks 60 and back 58 in contact with the backrest 24, allowing the spine 59 to form a natural S-curve and maintaining a healthy neck posture. The chair 20 of the present invention can correct a hunched posture and prevent the onset of straight neck, even when sitting directly on the tatami mat in a Japanese-style room and using a smartphone or other electronic device.

The present invention is not limited to personal computers, game consoles that use displays, and portable game consoles,
It is possible to use a chair with the functionality to prevent smart neck and maintain a healthy posture for the neck when using or reading a mobile information device such as a smartphone or tablet based on ergonomics.

10 Functional chair 12 Armrest 14 Backrest 16 Seat 18 Legs 20 Chair 22 Armrest 24 Backrest 26 Seat 50 User 51 Head 52 Eyes 53 Neck 54 Acromion point 55 Upper arm 56 Elbow 57 Forearm 58 Back 59 Spine 60 Buttocks 80 General chair with armrests 81 General chair without armrests 82 Armrest 84 Backrest 86 Seat DS Top plate ME Smartphone or other DP Display KB Keyboard

Claims (6)

A functional chair having at least a seat, a backrest, and armrests for use when using desktop or portable computer equipment,
The backrest,
It is formed to a height that supports the user's buttocks to at least the neck,
The angle between the seat surface and the backrest is an obtuse angle, and the seat has a gentle curved shape that is inclined toward the user above the upper part of the shoulder blades and continues in the height direction,
The armrest upper surface height is
Between 300mm and 400mm from the seat surface,
A functional chair characterized by its functionality. A functional chair having at least a seat, a backrest, and armrests for use when using desktop or portable computer equipment,
The backrest,
The angle between the seat surface and the backrest is an obtuse angle, and the backrest is formed to a height that supports at least the neck of the user. The backrest has a recess in a symmetrical shape at the center of the top surface.
The armrest upper surface height is
Between 300mm and 400mm from the seat surface,
A functional chair characterized by its functionality. The backrest,
integrally formed,
3. The functional chair according to claim 1 or 2. The backrest,
Between the rear lower ends of the armrests on both sides and the neck area, a continuous gentle recess is formed in the central vertical axis direction and extends integrally,
The narrowest point of the recess is
Narrower than the width of the seat
3. The functional chair according to claim 1 or 2. The distance between the armrests on both sides is
The armrest extends gradually and continuously from the upper end thereof to the connecting portion with the seat surface.
3. The functional chair according to claim 1 or 2. The obtuse angle is
It is set at 100 to 110 degrees.
A functional chair according to claim 1 or claim 2.