Chair

Abstract

The present disclosure relates to a chair for reducing the burden on the upper body of an occupant. A chair includes a chair body including a backrest, the backrest including a backrest surface, the backrest surface including an inclined surface inclined obliquely rearward toward an upper end portion of the backrest, and a protrusion protruding from the inclined surface and having a lower hardness than the chair body. The protrusion applies a reaction force to a part of the upper body of the occupant. Thus, the specific part of the upper body is prevented from being located rearward. As a result, the burden on the upper body is reduced.

Description

Technical Field

[0001] This disclosure relates to a chair. Background Technology

[0002] In the prior art, various technologies concerning chairs with backrests are known. For example, the first type of chair has a convex sponge layer to relieve lower back pain. The sponge layer is disposed in the backrest of the backrest, corresponding to the concave portion of the human waist (Japanese Patent Application Publication No. 2003-79477). The second type of chair has a convex auxiliary part, thereby "reducing the load on the back muscles" in an S-shaped posture. The auxiliary part is disposed in the backrest of the backrest, corresponding to the flat portion of the human waist (Japanese Patent Application Publication No. 2016-112117). Summary of the Invention

[0003] The technical problem that the invention aims to solve

[0004] Additionally, some chairs with backrests have a sloping backrest. This sloping surface tilts upwards and backwards towards the upper part of the backrest. In chairs with such a sloping surface, the upper body of the seated user may lean excessively backwards. In other words, when the user sits on the seat and leans against the backrest, their upper body leans backwards along the sloping surface. With this movement, certain parts of the upper body located higher than the backrest (such as the neck) move further backwards. As a result, for example, the user's upper body may bear a strain.

[0005] This disclosure provides a technique that can solve the above-mentioned problems.

[0006] Technical means to solve technical problems

[0007] The chair described in this embodiment can be implemented, for example, in the following manner.

[0008] (1) The chair involved in the embodiments of this disclosure includes a chair body and a protrusion. The chair body includes a backrest, the backrest includes a backrest surface, the backrest surface includes an inclined surface, the inclined surface is inclined to the upper end of the backrest to the upper rear side, and the protrusion protrudes from the inclined surface and has a lower hardness than the chair body.

[0009] One embodiment of this disclosure relates to a chair backrest having an inclined surface that slopes upwards and backwards. Normally, when a user sits on the seat and leans against the backrest, the user's upper body leans backwards along the inclined surface. Consequently, certain parts of the upper body located higher than the backrest (e.g., the neck) are positioned further back. This can, for example, put strain on the upper body. In contrast, in the chair of this embodiment, a protrusion is arranged to project from the inclined surface. The stiffness of the protrusion is lower than that of the chair body. Therefore, the protrusion exerts a reaction force on a portion of the upper body. In this way, it is possible to prevent specific parts of the upper body from being positioned further back. As a result, the strain on the upper body is reduced.

[0010] (2) In the structure of the chair according to other embodiments of this disclosure, the protrusion may include a first protrusion and a second protrusion. The first protrusion may be disposed on the inclined surface and has a first rebound force. The second protrusion may be disposed on the first protrusion and has a second rebound force, which may be less than the first rebound force. According to the chair according to this embodiment, the second protrusion with a relatively low rebound force can softly accommodate the upper body, while the first protrusion with a relatively high rebound force can support the upper body.

[0011] (3) In the structure of the chair according to other embodiments of this disclosure, the upper end of the second protrusion may be located at a position lower than the upper end of the first protrusion, and the lower end of the second protrusion may be located at a position higher than the lower end of the first protrusion. According to the chair according to this embodiment, for example, it is possible to suppress the impact of the protrusion on the overall appearance of the chair.

[0012] (4) In the structure of the chair according to other embodiments of this disclosure, the chair may further include a cover that can cover the protrusion and the entire backrest. According to this embodiment, the cover can suppress the impact of the protrusion on the overall appearance of the chair.

[0013] It should be noted that this embodiment can be implemented in various ways. For example, this embodiment can be implemented as "a chair, a chair body, and a backrest". Attached Figure Description

[0014] Figure 1 This is an explanatory diagram schematically showing the structure of the chair 10 according to the first embodiment.

[0015] Figure 2 It means Figure 1 An explanatory diagram of the XZ cross-sectional structure of chair 10 at position II-II.

[0016] Figure 3This is an explanatory diagram schematically showing the structure of the chair body 100.

[0017] Figure 4 It means Figure 3 An explanatory diagram of the XZ cross-sectional structure of the chair body 100 at position IV-IV.

[0018] Figure 5 This is an explanatory diagram showing the posture of a human body seated on the chair 10X in the reference example.

[0019] Figure 6 This is an explanatory diagram showing the posture of a human body seated on the chair 10 of this embodiment.

[0020] Figure 7 This is an explanatory diagram schematically showing the structure of the chair 10A according to the second embodiment. Detailed Implementation

[0021] A. First implementation method:

[0022] A-1. External structure of chair 10:

[0023] Reference Figures 1 to 6 The chair according to the first embodiment will be described. It should be noted that in each figure, mutually orthogonal XYZ axes are shown for determining orientation. The positive Z-axis direction is the upward direction. The negative Z-axis direction is the downward direction. The positive X-axis direction is the forward direction. The negative X-axis direction is the backward direction. Additionally, the positive Y-axis direction is the rightward direction. The negative Y-axis direction is the leftward direction.

[0024] Chair 10 is a sofa-type chair that can seat 2 to 3 people simultaneously. Chair 10 is used, for example, in residences, offices, shops, hotels, or public facilities. The height of chair 10 is, for example, 680mm or more and 880mm or less (more specifically, approximately 780mm). The width of chair 10 in the left-right direction is, for example, 1600mm or more and 2000mm or less (more specifically, approximately 1815mm). The depth of chair 10 in the front-back direction is, for example, 700mm or more and 900mm or less (more specifically, approximately 800mm).

[0025] like Figure 1 As shown, the chair 10 includes an outer seat portion 20, an outer backrest 40, and a pair of outer armrests 60. The outer surface N of the chair 10 includes an outer seat surface N20, an outer backrest surface N40, and a pair of outer armrest surfaces N60. The outer seat surface N20 is the upper surface of the outer seat portion 20. The outer backrest surface N40 is the front surface of the outer backrest 40. The outer armrest surfaces N60 are the upper surfaces of the outer armrests 60.

[0026] (Outer seat 20)

[0027] The outer seat portion 20 is primarily used to support the occupant's buttocks. The outer seat portion 20 has a transversely elongated structure extending in the left-right direction. The outer seat surface N20 slopes gradually downwards from the front to the rear (see reference). Figure 2 This prevents the occupant's pelvis from sliding forward. Simultaneously, it facilitates the occupant's (V) ability to lean against the outer backrest 40. The height from the ground to the front end of the outer seat surface N20 is set, for example, to be between 395mm and 495mm (more specifically, approximately 440mm), so that the occupant's feet can easily reach the floor surface. Furthermore, the height from the floor surface to the rear end of the outer seat surface N20 is lower than the front end. This height is set, for example, to be between 285mm and 375mm (more specifically, approximately 330mm). The length of the outer seat surface N20 in the lateral direction is set, for example, to be between 1255mm and 1655mm (more specifically, approximately 1455mm). The length of the outer seat surface N20 in the longitudinal direction is set, for example, to be between 460mm and 490mm (more specifically, approximately 475mm). Therefore, 2 to 3 people can sit on the outer seat surface N20.

[0028] (Outer backrest 40)

[0029] The outer backrest 40 is primarily used to support the back of the occupant V. The outer backrest 40 extends upwards from near the rear end of the outer seat portion 20. The outer backrest 40 has a transversely elongated structure extending in the left-right direction. The outer backrest 40 has a forward-projecting shape near its left and right ends (see reference). Figure 1 Therefore, the passenger V can place their hands on the outer backrest 40 to facilitate standing up. The outer backrest 40 is generally curved (streamlined), thus giving it a high level of aesthetic appeal.

[0030] (Outer handrail 60)

[0031] A pair of outer armrests 60 primarily support the elbows of the occupant V. The left outer armrest 60 extends upward from near the left end of the outer seat 20. The right outer armrest 60 extends upward from near the right end of the outer seat 20. Each outer armrest 60 protrudes upward from the outer seat surface N20 as it faces forward (see reference). Figure 2 The outer handrails 60 are generally composed of curved surfaces (streamlined shape), thus the outer handrails 60 have a high aesthetic appeal.

[0032] A-2. Internal structure of chair 10:

[0033] like Figure 2As shown, the chair 10 includes a chair body 100, a cushioning member 90, and a cover member 95. The cushioning member 90 is disposed on the upper surface of the chair body 100. The cover member 95 is disposed on the upper surface of the cushioning member 90.

[0034] (Chair body 100)

[0035] like Figure 3 As shown, the chair body 100 is a functional component (core material) that defines the general shape of the chair 10. The chair body 100 has an inner seat 120, an inner backrest 140, and a pair of inner armrests 160. The inner seat 120 is positioned corresponding to the outer seat 20 of the chair 10. The shape of the inner seat 120 is similar to... Figure 1 The outer seat portion 20 shown has a generally similar shape. The shape of the inner seat portion 120 defines the shape of the outer seat portion 20. A recess is provided on the upper surface of the inner seat portion 120. A step is provided on the front surface of the inner seat portion 120. The inner backrest 140 is positioned corresponding to the outer backrest 40 of the chair 10. The shape of the inner backrest 140 is similar to... Figure 1 The outer backrest 40 shown has a generally similar shape. The shape of the inner backrest 140 defines the shape of the outer backrest 40. The inner armrest 160 is positioned corresponding to the outer armrest 60 of the chair 10. The shape of the inner armrest 160 is similar to... Figure 1 The outer armrests shown are generally similar in shape. The inner armrest 160 defines the shape of the outer armrest 60. The inner seat 120 is an example of a seat. The inner backrest 140 is an example of a backrest.

[0036] It should be noted that, in this embodiment, as Figure 3 As shown, the chair body 100 includes a pair of first body parts 200 and a second body part 300. Figure 3 The first dashed line R1 and the second dashed line R2 in the diagram represent the boundary lines between the first body component 200 and the second body component 300 on the chair 10. The second body component 300 is disposed at the center of the chair body 100. Each of the first body components 200 is disposed adjacent to the second body component 300 in the left-right direction. Specifically, one first body component 200 is located to the right of the second body component 300 and is adjacent to the right end of the second body component 300. The other first body component 200 is located to the left of the second body component 300 and is adjacent to the left end of the second body component 300. The first body component 200 and the second body component 300 are joined together via a connecting member (not shown).

[0037] The first body component 200 is formed, for example, of a foam. A foam is a porous body formed by finely dispersing gas in a resin. Examples of foams used to form the first body component 200 include expanded polystyrene, expanded polyurethane, and expanded olefins. Examples of expanded polystyrene, depending on its manufacturing method, include bead-formed expanded polystyrene (EPS), expanded polystyrene sheet (PSP), and extruded expanded polystyrene (XPS). The second body component 300 is formed, for example, of a non-foamed material. Examples of non-foamed materials include wood, metal materials (including iron and stainless steel), and unfoamed resin materials. In this embodiment, the second body component 300 is made of wood. In this embodiment, the second body component 300 is formed of a material (wood) that has higher strength than a foam. Therefore, the chair body 100 (and thus the chair 10) possesses the required structural strength.

[0038] (Buffer component 90)

[0039] like Figure 2 As shown, the cushioning member 90 is configured to cover the upper surface of the inner seat 120, the front surface of the inner backrest 140, the inner surfaces, upper surfaces, and front surfaces of the pair of inner armrests 160 of the chair body 100. The cushioning member 90 is a component used to soften the outer seat surface N20, the outer backrest surface N40, and the outer armrest surface N60 of the chair 10. In this embodiment, the cushioning member 90 includes a first cushioning member 91, a second cushioning member 92, a third cushioning member 93, and a fourth cushioning member 94.

[0040] The first cushioning member 91 and the second cushioning member 92 have approximately the same dimensions and are generally rectangular plates (not shown). The length of the first cushioning member 91 and the second cushioning member 92 in the X-axis direction is approximately 0.8 times the length of the seat surface of the inner seat portion 120 in the X-axis direction. The length of the first cushioning member 91 and the second cushioning member 92 in the Y-axis direction is approximately the same as the length of the partial surface of the seat of the inner seat portion 120 in the Y-axis direction. The first cushioning member 91 is disposed in a recess provided on the upper surface of the inner seat portion 120 of the chair body 100. The second cushioning member 92 is disposed on the upper surface of the first cushioning member 91 and is received in the recess of the inner seat portion 120.

[0041] The third buffer member 93 has a generally rectangular plate shape (not shown). The length of the third buffer member 93 in the Y-axis direction is the same as the length of the second buffer member 92 in the Y-axis direction. The length of the third buffer member 93 in the X-axis direction is approximately 1.2 times the length of the second buffer member 92 in the X-axis direction. The third buffer member 93 is arranged to cover the upper surface of the second buffer member 92, and on the front surface side of the chair body 100, it covers the ends of the first buffer member 91 and the second buffer member 92. Furthermore, the third buffer member 93 is housed in a recess provided on the upper surface of the inner seat portion 120. The front end face of the third buffer member 93 is in contact with the surface of the recess provided on the upper surface of the inner seat portion 120.

[0042] The fourth cushioning member 94 is arranged to cover the upper surface of the inner backrest 140, the upper surfaces of the pair of inner armrests 160, and the upper surface of the third cushioning member 93. The front end face of the fourth cushioning member 94 contacts the upper surface of the step provided on the front surface side of the inner seat portion 120. Thus, the upper surface of the fourth cushioning member 94 and the front surface of the inner seat portion 120 form a continuous surface. The cushioning member 90 is fixed to the chair body 100, for example, by an adhesive (synthetic rubber solvent). In addition, the first cushioning member 91, the second cushioning member 92, the third cushioning member 93, and the fourth cushioning member 94 are fixed, for example, by an adhesive (synthetic rubber solvent).

[0043] The cushioning member 90 can be made of any material that softens the area around the outer seat surface N20, the outer backrest N40, and the outer armrest surface N60. Examples of materials for the cushioning member 90 include polyurethane, sheet polyurethane, high-resilience polyurethane, low-resilience polyurethane, and rubber. In this embodiment, the first cushioning member 91 is made of sheet polyurethane. The second cushioning member 92 and the third cushioning member 93 are made of high-resilience polyurethane. The fourth cushioning member 94 is made of low-resilience polyurethane.

[0044] (Cover component 95)

[0045] The cover component 95 is a component that covers the surface of the structure of the chair 10, which includes the chair body 100 and the cushioning component 90. The material of the cover component 95 is, for example, resin cotton. By providing the cover component 95, it is possible to suppress soiling of the chair body 100 and the cushioning component 90. Furthermore, it can impart a cooling or warming function to the outer seat surface N20, the outer backrest N40, and the outer armrest surface N60. The cover component 95 may cover the entire surface of the structure. Alternatively, the cover component 95 may cover only a portion of the structure's surface (e.g., exposing a portion of the lower surface). The cover component 95 is fixed to the chair body 100, for example, using a nail gun. Additionally, the cover component 95 is fixed to the chair body 100, for example, using a zipper and a tension cord provided on the cover component 95.

[0046] A-3. Regarding the convex part:

[0047] The chair 10 in this embodiment also includes a protrusion 70. For example... Figure 3 and Figure 4 As shown, the protrusion 70 is disposed on the inner backrest M40 of the chair body 100. The inner backrest M40 is the surface of the outer surface of the chair body 100 that corresponds to the outer backrest N40 described above. The inner backrest M40 is an example of a backrest. Specifically, the protrusion 70 is disposed in such a way that it protrudes from the inclined surface M42 in the inner backrest M40. The inclined surface M42 is a surface in the inner backrest M40 that slopes upward and backward toward the upper end portion 22 of the inner backrest 140. In this embodiment, the inclined surface M42 extends continuously to the upper end portion 22 of the inner backrest 140. Furthermore, the inclined surface M42 slopes continuously in such a way that it is located further backward the closer it is to the upper end portion 22 of the inner backrest 140. The inclined surface M42 may also be a plane that slopes in a straight line. Alternatively, the inclined surface M42 may also be a curved surface that is bent into a convex or concave shape.

[0048] Furthermore, in this embodiment, the tilt angle θ1 of the inclined surface M42 relative to the horizontal plane (XY plane) (refer to...) Figure 2 The definition is as follows: Figure 2 As shown, the inclination direction of the inclined surface M42 refers to the direction parallel to a dashed line R, which connects the intersection point T1 between the upper end of the protrusion 70 and the inclined surface M42, and the intersection point T2 between the lower end of the protrusion 70 and the inclined surface M42. The inclination angle θ1 is the inclination angle of the dashed line R relative to the horizontal plane (XY plane, horizontal line H). The inclination angle θ1 is, for example, 110 degrees (supplementary angle 70 degrees). The inclination angle θ1 of the inclined surface M42 can be 95 degrees or more (supplementary angle less than 85 degrees) and less than 150 degrees (supplementary angle more than 30 degrees), or 100 degrees or more (supplementary angle less than 80 degrees) and less than 135 degrees (supplementary angle more than 45 degrees), or 105 degrees or more (supplementary angle less than 75 degrees) and less than 120 degrees (supplementary angle more than 60 degrees).

[0049] The hardness of the protrusion 70 is lower than that of the chair body 100. The protrusion 70 is formed of a material with resilience. Examples of materials forming the protrusion 70 include cushioning materials such as polyurethane, sheet polyurethane, high-resilience polyurethane, low-resilience polyurethane, and rubber.

[0050] The protrusion 70 is positioned at a height corresponding to the lower part of the scapula V1 (the fifth to eighth thoracic vertebrae) in the human body of a passenger V (e.g., an adult of average height). In this embodiment, the height of the protrusion 70 (its center in the vertical direction) from the outer seat surface N20 of the outer seat portion 20 (hereinafter referred to as the height position L of the protrusion 70, as described later) is... Figure 6 The height is set to be equivalent to the position of the lower part of the scapula V1 (fifth to eighth thoracic vertebrae) of the human body when seated on the outer seat surface N20. Here, with almost no depression in the outer seat surface N20, the height position L of the protrusion 70 can, for example, be within a range including at least one of the following height ranges A to D.

[0051] • Height range A: 471.1mm or higher and less than 493.7mm (corresponding to the fifth thoracic vertebra)

[0052] • Height range B: Above 448.5mm and less than 471.1mm (corresponding to the sixth thoracic vertebra)

[0053] • Height range C: 425.9mm or higher and less than 448.5mm (corresponding to the seventh thoracic vertebra)

[0054] • Height range D: 403.3mm or more and less than 425.9mm (corresponding to the eighth thoracic vertebra)

[0055] Specifically, the height position L of the protrusion 70 can be within the height range C, or it can be within the range encompassing all height ranges A to D (above 350mm and below 540mm). It should be noted that, assuming the outer seat surface N20 is not recessed, the height of the protrusion 70 from the seat surface (inner seat surface) of the inner seat portion 120 of the chair body 100 is calculated using the following formula:

[0056] "The height of the protrusion 70 from the inner seat surface of the chair body 100" = "The height position L of the protrusion 70 (the above height range)" + "The thickness of the cushioning member 90 and the cover member 95" (if there is no cushioning member, the thickness is "0").

[0057] In this embodiment, the outer seat surface N20 will sink due to the weight of the occupant V. The amount of sinking of the outer seat surface N20 depends on the weight of the occupant V. The sinking amount is, for example, approximately 20 mm. Alternatively, the sinking amount may be more than 10 mm and less than 60 mm, or more than 15 mm and less than 29 mm. Therefore, in the state before sitting (sinking), the height of the protrusion 70 (center in the vertical direction) from the outer seat surface N20 of the outer seat portion 20 (hereinafter referred to as the height position of the protrusion 70 before sitting) is calculated by the following formula:

[0058] "Height position of the 70° protrusion after seating" = "Height position of the 70° protrusion L - Amount of depression"

[0059] In this embodiment, the height of the protrusion 70 before seating is approximately 340 mm. It should be noted that when the outer seat surface N20 is recessed, the height of the protrusion 70 from the seat surface (inner seat surface) of the inner seat portion 120 of the chair body 100 is calculated using the following formula:

[0060] "Height of protrusion 70 from the seat surface of chair body 100" = "Height position L of protrusion 70" + ("Thickness of cushioning component 90 and cover component 95 before sinking" - "Sinking amount") = "Height position L of protrusion 70" + "Thickness of cushioning component 90 and cover component 95 after sinking"

[0061] "The height of the seat surface 70 from the protrusion 100 of the chair body" can be, for example, 300mm or more and 700mm or less, 400mm or more and 600mm or less, or 300mm or more and 500mm or less.

[0062] It should be noted that, in this embodiment, the method for measuring the hardness of each component is as follows.

[0063] (1) Place the sample of the component to be measured in a constant temperature chamber with a set temperature of 25°C and a set humidity of 50% for more than 16 hours.

[0064] (2) The samples taken from the constant temperature chamber were measured five times using a hardness tester under the following conditions. The five measurements were performed almost continuously without interruption. Test environment: temperature 28.2℃, humidity 76%.

[0065] (3) Of the five measurements, the first two are not used. The average of the third and subsequent measurements is defined as the hardness of the component being measured. The first two measurements are usually too high. The measurements from the third measurement onward tend to be stable. Therefore, the first two are considered preliminary measurements.

[0066] The protrusion 70 has a first protrusion 72 and a second protrusion 74. The first protrusion 72 is disposed on the inclined surface M42. The first protrusion 72 is fixed to the inclined surface M42, for example, by an adhesive (synthetic rubber solvent). The second protrusion 74 is disposed on the first protrusion 72. The second protrusion 74 is fixed to the first protrusion 72, for example, by an adhesive (synthetic rubber solvent). The first protrusion 72 has a first resilience. The second protrusion 74 has a second resilience lower than the first resilience. Specifically, the first protrusion 72 is formed of high-resilience polyurethane. The second protrusion 74 is formed of low-resilience polyurethane.

[0067] It should be noted that, as Figure 2As shown, the fourth cushioning member 94 covers the entire inner side of the protrusion 70 near the back surface M40. The fourth cushioning member 94 is an example of a cover. The rebound force of the first protrusion 72 may also be higher than the rebound force of the fourth cushioning member 94. The rebound force of the second protrusion 74 may be higher than, the same as, or lower than the rebound force of the fourth cushioning member 94.

[0068] It should be noted that the method for measuring the resilience of each component in this instruction manual is as follows:

[0069] (1) Place the sample of the component to be tested in a constant temperature chamber with a set temperature of 25°C and a set humidity of 50% for more than 16 hours.

[0070] (2) Place the sample taken from the constant temperature chamber flat on the test bench of the tensile tester. It should be noted that the diameter of the pressure rod head of the tensile tester is 50 mm. Perform five measurements on the sample using the tensile tester under the following conditions: five measurements are performed continuously and almost continuously; the sample is compressed to 66 mm at a pressure rate of 100 mm / min; test environment: temperature 28.2℃, humidity 76%.

[0071] (3) Of the five measurements, the first two are not used. The average of the measurements from the third measurement onwards is defined as the rebound force of the measured part. The first two measurements tend to be stiff, while the values ​​from the third measurement onwards tend to be stable. Therefore, the first two measurements are considered as pre-compression.

[0072] In this embodiment, the hardness relationship among the fourth buffer member 94, the first protrusion 72, and the second protrusion 74 is as follows:

[0073] "The hardness of the first protrusion (72) > the hardness of the fourth buffer component (94) > the hardness of the second protrusion (74)"

[0074] The hardness of the first protrusion 72 is, for example, 65 degrees. The hardness of the first protrusion 72 can also be 60 degrees or higher and 70 degrees or lower, or 63 degrees or higher and 67 degrees or lower. The hardness of the fourth buffer member 94 is, for example, 30 degrees. The hardness of the fourth buffer member 94 can also be 25 degrees or higher and 35 degrees or lower, or 28 degrees or higher and 33 degrees or lower. The hardness of the second protrusion 74 is, for example, 20 degrees. The hardness of the second protrusion 74 can also be 15 degrees or higher and 25 degrees or lower, or 18 degrees or higher and 22 degrees or lower. The hardness of the first protrusion 72 can be more than twice, or more than three times, the hardness of the second protrusion 74. The hardness of the first protrusion 72 can also be more than twice the hardness of the fourth buffer member 94.

[0075] In this embodiment, the relationship between the magnitudes of the rebound forces of the fourth buffer member 94, the first protrusion 72, and the second protrusion 74 is as follows:

[0076] The rebound force of the second protrusion 74 > the rebound force of the fourth buffer component 94 > the rebound force of the first protrusion 72

[0077] The rebound force of the first protrusion 72 is, for example, 6N. The rebound force of the first protrusion 72 can be 3N or more and 9N or less, or 5N or more and 7N or less. The rebound force of the fourth buffer member 94 is, for example, 21N. The rebound force of the fourth buffer member 94 can be 16N or more and 26N or less, or 19N or more and 23N or less. The rebound force of the second protrusion 74 is, for example, 22.5N. The rebound force of the second protrusion 74 can be 17.5N or more and 27.5N or less, or 20N or more and 25N or less. The rebound force of the second protrusion 74 can be more than twice the rebound force of the first protrusion 72, or more than three times. The rebound force of the first protrusion 72 can also be less than one-third of the rebound force of the fourth buffer member 94.

[0078] In this embodiment, the thickness relationship between the fourth buffer member 94, the first protrusion 72, and the second protrusion 74 is as follows:

[0079] "The thickness of the fourth buffer component 94 > the thickness of the first protrusion 72 = the thickness of the second protrusion 74"

[0080] The thickness of the fourth buffer member 94 is, for example, 60 mm. The thickness of the fourth buffer member 94 can be 55 mm or more and 65 mm or less, or 58 mm or more and 62 mm or less. The thickness of the first protrusion 72 and the thickness of the second protrusion 74 are both, for example, 20 mm. The thickness of the first protrusion 72 and the thickness of the second protrusion 74 can be 15 mm or more and 25 mm or less, or 18 mm or more and 22 mm or less. It should be noted that the thickness of the cover member 95 is, for example, 20 mm. The thickness of the cover member 95 can be 15 mm or more and 25 mm or less, or 17 mm or more and 23 mm or less. The thickness of the third buffer member 93 is, for example, 40 mm. The thickness of the third buffer member 93 can be 35 mm or more and 45 mm or less, or 37 mm or more and 43 mm or less. The thickness of the second buffer member 92 is, for example, 20 mm. The thickness of the second buffer member 92 can be 15 mm or more and 25 mm or less, or 17 mm or more and 23 mm or less. The thickness of the first buffer member 91 is, for example, 50 mm. The thickness of the first buffer member 91 can be 45 mm or more and 55 mm or less, or it can be 47 mm or more and 53 mm or less.

[0081] The protrusion 70 is a convex component that extends linearly along the left-right direction. In this embodiment, the protrusion 70 is continuously provided along the entire length of the inner backrest 140 (outer backrest 40) in the left-right direction. The length of the protrusion 70 in the left-right direction (length along the longer side) is, for example, 545 mm. However, the protrusion 70 is not limited to this, and its length can be set differently depending on the length of the chair 10 in the left-right direction. The length of the protrusion 70 in the vertical direction (length along the shorter side) is 120 mm. The length of the protrusion 70 in the vertical direction can be 60 mm or more and 160 mm or less, or it can be 70 mm or more and 130 mm or less.

[0082] Specifically, such as Figure 3 As shown, both the first protrusion 72 and the second protrusion 74 are flat plate-shaped components extending linearly in the left-right direction. The length of the first protrusion 72 in the left-right direction (length in the long side direction) is approximately the same as the length of the second protrusion 74 in the left-right direction, for example, 545 mm. The length of the second protrusion 74 in the vertical direction (length in the short side direction) is less than the length of the first protrusion 72 in the vertical direction. The length of the first protrusion 72 in the vertical direction is, for example, 120 mm. The length of the first protrusion 72 in the vertical direction can be 80 mm or more and 160 mm or less, or it can be 100 mm or more and 130 mm or less.

[0083] The vertical length of the second protrusion 74 is set to correspond to the position of the lower part of the scapula (V1, 5th to 8th thoracic vertebrae). Specifically, assuming the average height of a single thoracic vertebra is 17.7 mm or more and 22.6 mm or less, the vertical length of the second protrusion 74 can also be set to be greater than or equal to the minimum vertical length corresponding to a single thoracic vertebra (i.e., 17.7 mm) and less than or equal to the maximum vertical length corresponding to four thoracic vertebrae (i.e., 90.4 mm). Alternatively, the vertical length of the second protrusion 74 can also be 70.8 mm or more and 90.4 mm or less corresponding to four thoracic vertebrae, 53.1 mm or more and 67.8 mm or less corresponding to three thoracic vertebrae, 35.4 mm or more and 45.2 mm or less corresponding to two thoracic vertebrae, or 17.7 mm or more and 22.6 mm or less corresponding to a single thoracic vertebra. Furthermore, considering the durability and versatility of the second protrusion 74, it is preferable that the length of the second protrusion 74 in the vertical direction is in the range of 53.1 mm or more and 90.4 mm or less.

[0084] The upper end of the second protrusion 74 is located lower than the upper end of the first protrusion 72, and the lower end of the second protrusion 74 is located higher than the lower end of the first protrusion 72. The first protrusion length of the first protrusion 72 protruding upward from the second protrusion 74 and the second protrusion length of the first protrusion 72 protruding downward from the second protrusion 74 are the same (e.g., 50 mm). The first protrusion length and the second protrusion length can be the same (e.g., more than 40 mm or more, or more than 50 mm) or different.

[0085] A-4. Effects of this implementation method:

[0086] Figure 5 This is an explanatory diagram showing the posture of a person sitting in the reference chair 10X. (Example:) Figure 5 As shown, chair 10X differs from chair 10 in that it lacks the protrusion 70. Its other structure is the same as chair 10. Because chair 10X lacks the protrusion 70, the upper body of the occupant V leans backward along the outer backrest N40 (inner backrest M40). Consequently, certain parts of the upper body (e.g., the neck) located higher than the backrest are positioned further back. As a result, the occupant V's neck is excessively tilted back, causing neck strain. Therefore, the occupant V may not be able to sit in the chair for extended periods.

[0087] In chair 10X, the seat surface of the inner seat portion 120 (the outer seat surface N20 of the outer seat portion 20) is an inclined surface that is higher in the front and lower in the back. This inclined surface slopes downward and backward towards the inner backrest M40. Similarly, the inner backrest M40 (the backrest of the outer backrest 40) is an inclined surface that is lower in the front and higher in the back. This inclined surface slopes downward and forward towards the inner seat portion 120. Therefore, in a chair with a seat surface and backrest that are both higher in the front and lower in the back, it is particularly easy to put strain on the upper body of the occupant V. In other words, due to the inclination of the seat surface, the occupant V's hips will sink downward relative to the knees. Furthermore, due to the inclination of the backrest, the body's center of gravity tends to shift backward. In order to achieve balance in the front-back direction (adjusting the body's center of gravity forward), the occupant V will attempt to lift their upper body forward and move their neck forward. Therefore, this may put strain on the upper body.

[0088] Figure 6 This is an explanatory diagram showing the posture of a human body seated on the chair 10 according to this embodiment. Figure 6 As shown, similar to the chair 10X in the reference example, the chair 10 of this embodiment also has a seat surface that is higher in the front and lower in the back, and a backrest that is lower in the front and higher in the back. The inclination angle θ2 of the seat surface of the inner seat portion 120 (refer to...) Figure 2For example, 25 degrees relative to the horizontal direction. The seat surface tilt angle θ3 can be greater than 20 degrees and less than 30 degrees. The tilt angle θ3 of the inner side against the back M40 (the tilt angle of the surface of the approximate central part in the vertical direction of the inner side against the back M40, or the tilt angle of the flattest surface, refer to...) Figure 2 For example, it is 110 degrees relative to the horizontal direction. The tilt angle θ3 of the inner backrest M40 can also be more than 100 degrees and less than 120 degrees. In addition, the tilt angle θ4 of the lower backrest of the inner backrest M40 (the backrest of the inner backrest 140) below the specified height of the seat surface (for example, it can also be more than 210 mm, or more than 117 mm and less than 226 mm) (see reference) Figure 2 The inclination angle of the upper backrest (θ3 of the inner backrest M40) can be steeper than the specified height of the seat surface. The inclination angle θ4 of the lower backrest is, for example, 85 degrees relative to the horizontal direction. The inclination angle θ4 of the lower backrest can also be more than 80 degrees and less than 90 degrees. As a result, the occupant V can easily maintain the posture in the original mid-position of the pelvis. It should be noted that the inclination angle θ4 of the seat surface of the inner seat 120 can be, for example, the inclination angle of the central portion of the seat surface in the front-rear direction. Alternatively, it can be the inclination angle of the approximately flat and largest area portion of the seat surface portion extending toward the front of the seat surface from the rear end of the seat surface to the front end of the seat surface at a position of more than 15 cm and less than 20 cm.

[0089] The chair 10 has a protrusion 70. The protrusion 70 is disposed on the inclined surface M42. The protrusion 70 has a lower stiffness (Young's modulus) than the chair body 100. In the fourth cushioning member 94 and the cover member 95, the portion covering the protrusion 70 protrudes in a convex shape. In this embodiment, the protrusion 70 is disposed at a height corresponding to the position of the lower scapula V1 of the occupant V sitting on the outer seat 20 of the chair 10. On the chair 10, the upper body of the occupant V is also in a posture of leaning backward along the outer backrest N40 (inner backrest M40). However, the protrusion 70 exerts a reaction force on the area near the lower scapula V1 of the upper body. Thus, the protrusion 70 can inhibit excessive tilting of the neck, thereby reducing the burden on the upper body. Normally, of the twelve thoracic vertebrae in the human body, the seventh thoracic vertebra is located at the rear. Moreover, the protrusion 70 is disposed in the inner backrest M40 corresponding to the area of ​​the fifth to eighth thoracic vertebrae, which include the seventh thoracic vertebra. This allows the head, cervical spine, and thoracic spine to remain stable in an ideal position that does not cause stress.

[0090] In the chair 10 of this embodiment, the protrusion 70 has a structure in which a relatively low-resilience second protrusion 74 is disposed on a relatively high-resilience first protrusion 72. Therefore, the second protrusion 74, with its relatively low resilience, can softly accommodate the upper body. Meanwhile, the first protrusion 72, with its relatively high resilience, can support the upper body. Furthermore, the protrusion 70 is covered by a fourth cushioning member 94 and a cover member 95. This makes it easy for the shape of the chair 10 to become gentler. Therefore, compared to structures where both the first protrusion 72 and the second protrusion 74 have high resilience, the structure of the chair 10 according to this embodiment, for example, can suppress the influence of the presence of the protrusion 70 on the shape (aesthetic design) of the chair 10.

[0091] The upper end of the second protrusion 74 is located lower than the upper end of the first protrusion 72. Simultaneously, the lower end of the second protrusion 74 is located higher than the lower end of the first protrusion 72. Therefore, according to this embodiment, the protrusion 70 is configured in a stepped shape. This gives the protrusion 70 a shape with a two-stage change in height. As a result, the height changes gradually from the chair body 100 to the protrusion 70. Therefore, the impact of the presence of the protrusion 70 on the shape (aesthetic design) of the chair 10 can be more effectively suppressed.

[0092] The performance evaluation of the chair 10 according to this embodiment will be described. The chair 10 according to this embodiment can maintain a correct posture that is not prone to fatigue even after prolonged use. Here, correct posture refers to a state where the neck and waist are upright in the vertical direction. The following evaluation tests were conducted on the chair 10 of this embodiment and the chair 10X of the reference example.

[0093] • Participants: 19 healthy adult men and women (13 men and 6 women), aged 23.4 ± 4.9 years, with a height of 168.9 ± 9.3 cm and a weight of 64.1 ± 11.5 kg.

[0094] • Experimental method: Cross-test

[0095] Subjects were divided into Group A and Group B. Group A sat in chair 10 for the test time (30 minutes) on the first day, and then sat in chair 10X for the test time on the second day. Group B sat in chair 10X for the test time on the first day, and then sat in chair 10 for the test time on the second day. The subjects' sitting postures were then captured using a motion capture camera (e.g., Miqus, manufactured by Qualisy). The captured motion images were analyzed using 3D motion analysis software (e.g., a skeletal model / 3D motion analysis software manufactured by C-motion) to measure the angular displacement of the pelvis relative to the seat surface and the angular displacement of the torso relative to the ground during the test. It should be noted that the torso angle was considered as the angle of the thorax (neck).

[0096] The evaluation results showed that during the test period, a change in the pelvic angle of the occupant sitting in the reference chair 10X was observed, with a change of approximately 2 degrees. In contrast, during the test period, almost no change in the pelvic angle of the occupant sitting in the chair 10 of this embodiment was observed, with a change of less than 0.60 degrees. Furthermore, when seated, the pelvis of the occupant sitting in the chair 10 of this embodiment did not tilt further backward compared to the occupant sitting in the reference chair 10X.

[0097] Regarding the occupant's torso, during the test period, a change in the torso angle of the occupant sitting in the reference example chair 10X was observed, with a change of approximately 3 degrees. In contrast, during the test period, almost no change in the torso angle of the occupant sitting in the chair 10 involved in this embodiment was observed, with a change of less than 1 degree. Furthermore, when seated, compared to the occupant sitting in the reference example chair 10X, the occupant sitting in the chair 10 of this embodiment did not lean further back.

[0098] According to the evaluation results, the chair 10 of this embodiment, compared with the chair 10X of the reference example, can maintain a correct posture that is not easy to get tired even after long-term use.

[0099] B. Second implementation method:

[0100] Figure 7 This is an explanatory diagram that schematically illustrates the structure of the chair 10A according to the second embodiment. The chair 10A is a single-seat chair. Figure 7 As shown, the chair 10A includes a seat 20A, a backrest 40A, and a pair of armrests 60A. The backrest 40A has an inclined surface 42A. The inclined surface 42A is a surface that slopes upward and backward toward the upper end 22A of the backrest 40A in the backrest.

[0101] A protrusion 70A is provided on the inclined surface 42A. The protrusion 70A is located at the center position in the left-right direction near the back. The protrusion 70A is positioned at a height corresponding to the position of the lower part V1 of the scapula of the occupant V sitting on the outer seat 20 of the chair 10. The protrusion 70A is generally square in shape.

[0102] The protrusion 70A includes a first protrusion 72A and a second protrusion 74A. The first protrusion 72A is disposed on the inclined surface 42A. The first protrusion 72A is fixed to the inclined surface 42A, for example, by an adhesive (synthetic rubber solvent). The second protrusion 74A is disposed on the first protrusion 72A. The second protrusion 74A is fixed to the first protrusion 72A, for example, by an adhesive (synthetic rubber solvent). The first protrusion 72A has a first resilience. The second protrusion 74A has a second resilience lower than the first resilience. Specifically, the first protrusion 72A is made of high-resilience polyurethane. The second protrusion 74A is made of low-resilience polyurethane.

[0103] The upper end of the second protrusion 74A is located lower than the upper end of the first protrusion 72A. Simultaneously, the lower end of the second protrusion 74A is located higher than the lower end of the first protrusion 72A. The right end of the second protrusion 74A is located to the left of the right end of the first protrusion 72A. Simultaneously, the left end of the second protrusion 74A is located to the right of the left end of the first protrusion 72A. Thus, the protrusion 70A has a stepped structure. This gives the protrusion 70A a shape with a two-stage height change. As a result, the height change from the chair body 100 to the protrusion 70A is gradual. Therefore, the presence of the protrusion 70A can be prevented from affecting the shape (aesthetic design) of the chair 10.

[0104] In the chair 10A of this embodiment, the upper body of the occupant V leans backward along the backrest. However, the protrusion 70A exerts a reaction force on the area near the lower part of the scapula V1 of the upper body. In this way, the protrusion 70A can inhibit excessive backward tilting of the neck and reduce the burden on the upper body.

[0105] C. Variation example:

[0106] The embodiments disclosed herein are not limited to those described above. Various modifications can be made to the above embodiments without departing from their spirit. For example, the following modifications are also possible. The structure of the chair 10 in the above embodiments is merely an example and can be modified in various ways.

[0107] The chair 10 according to the first embodiment is a so-called sofa-type chair, suitable for seating 2 to 3 people. However, the chair according to this embodiment can also be a single-seat sofa-type chair. Furthermore, chairs 10 and 10A may also have leg components. Chairs 10 and 10A may also lack armrests.

[0108] The shape, size, and manufacturing method of the chair 10 described in the above embodiments are merely examples. Various modifications can be made to the above embodiments. The shape, size, forming material, and manufacturing method of each part of the chair 10 described above are also merely examples. Each part can be modified in various ways.

[0109] The chair 10 according to the first embodiment includes a cushioning member 90 and a cover member 95. However, at least one of them may be omitted. In addition, in the first embodiment, the cushioning member 90 has a four-layer structure. However, the number of layers, the material of each cushioning material, or the size of each cushioning material can be appropriately changed.

[0110] In the structure of the chair 10 according to the first embodiment, the chair body 100 has a pair of first body parts 200 and second body parts 300. However, in the structure of the chair 10, the chair body 100 may also be integrally formed from the same material.

[0111] In the structure of the chair 10 according to the first embodiment, a protrusion 70 is provided on the inner backrest 140 of the chair body 100. However, the protrusion 70 may also be provided on the outer backrest N40 of the outer backrest 40 of the chair 10. Furthermore, the chair 10 according to the first embodiment may not include at least one of the fourth cushioning member 94 and the cover member 95. The thickness of the fourth cushioning member 94 may also be set to be thinner than the thickness of the protrusion. The fourth cushioning member 94 may also have a double-layer structure or a structure with three or more layers. Additionally, in the structure of the chair 10 according to the first embodiment, one protrusion 70 is provided on the inclined surface M42 of the chair 10. Furthermore, in the structure of the chair 10A according to the second embodiment, one protrusion 70A is provided on the inclined surface 42A of the chair 10A. However, in the structure of the chair according to this embodiment, multiple (a pair, or more than three) protrusions may also be provided on the inclined surface. For example, multiple protrusions may also be arranged separately from each other along at least one of the horizontal and vertical directions. Specifically, a pair of protrusions arranged in the horizontal direction can also be configured on the inclined surface at a height position corresponding to the vicinity of the occupant's shoulder blades.

[0112] In the structure of the chair 10 according to the first embodiment, the protrusion 70 is arranged to protrude from the outer surface of the chair 10 (outer seat surface N20, etc.). Similarly, in the structure of the chair 10A according to the second embodiment, the protrusion 70A is arranged to protrude from the outer surface of the chair 10A (outer seat surface N20, etc.). However, the protrusion may also have a flat structure. In this structure, the protrusion is arranged on the outer surface of the chair at approximately the same height as the peripheral portion (buffer member, etc.) surrounding the protrusion. In other words, the protrusion can protrude from the inclined surface of the chair body. In the above-described flat structure, the protrusion preferably has a higher rigidity than the peripheral portion. Therefore, when the occupant leans against the backrest, the relatively less rigid peripheral portion sinks. Thus, the relatively more rigid protrusion protrudes, thereby supporting specific parts of the upper body.

[0113] In the first embodiment, the protrusion 70 has a double-layer structure including a first protrusion 72 and a second protrusion 74. In the second embodiment, it has a double-layer structure including a first protrusion 72A and a second protrusion 74A. However, it is not limited to this; the structure of the protrusion can be a single-layer structure or a structure with three or more layers. Examples of a single-layer protrusion include a protrusion with a flat or stepped structure integrally formed from the same raw material. Examples of a multi-layer protrusion include a protrusion having a structure with steps between layers. However, it is not limited to this; in such structures, the height of the protrusion can also vary gradually so that it does not have steps. Furthermore, the shape of the protrusions (70 and 70A) is not limited to rectangles or squares. For example, the shape can also be circular or elliptical.

[0114] Furthermore, the rebound force of the first protrusion 72 can be the same as or lower than the rebound force of the second protrusion 74. Similarly, the rebound force of the first protrusion 72A can be the same as or lower than the rebound force of the second protrusion 74A.

[0115] The resilience and hardness of the first protrusion 72 can be the same as those of the second protrusion 74. However, the thickness of the first protrusion 72 can be different from that of the second protrusion 74. Similarly, the resilience and hardness of the first protrusion 72A can be the same as those of the second protrusion 74A. Furthermore, the thickness of the first protrusion 72A can be different from that of the second protrusion 74A.

[0116] The chair disclosed herein is a chair having the following basic structure. In addition to the basic structure, the chair disclosed herein also includes a chair having at least one of the following structures (a) to (d).

[0117] (Basic Structure)

[0118] "A chair includes a chair body and a protrusion, the chair body including a backrest, the backrest including a backrest surface, the backrest including an inclined surface, the inclined surface being inclined upward and backward toward the upper end of the backrest, the protrusion protruding from the inclined surface and having a lower stiffness than the chair body."

[0119] • Structure (a): The seat surface of the chair body has an inclined surface that is higher in the front and lower in the back. This inclined surface slopes downwards and backwards towards the backrest. This helps to prevent the occupant's body from sliding forward. Furthermore, the inclined surface of the seat provides upright support for the occupant's pelvis. This makes it easier for the occupant to maintain a posture where their pelvis is in a natural, neutral position.

[0120] • Structure (b): The backrest of the chair body has an inclined surface that is lower in the front and higher in the back. This inclined surface slopes forward and downward towards the seat surface. This allows the occupant to relax.

[0121] • Structure (c): The backrest has a lower backrest. This lower backrest is positioned between the front-lower-rear-higher inclined surface (upper backrest) and the seat surface, and is steeper than the front-lower-rear-higher inclined surface. The lower backrest provides upright support for the occupant's pelvis. Therefore, the occupant can easily maintain a posture where the occupant's pelvis is in its natural neutral position.

[0122] It should be noted that in the chair body with structures (a) and (c), the angle θ5 formed by the seat surface and the lower backrest of the chair body (refer to...) Figure 2 It can also be below 100 degrees, below 90 degrees, or below 80 degrees.

[0123] • Structure (d): In structure (c), the convex portion is positioned on the inclined surface (upper side against the back). The lower side against the back provides upright support for the occupant's pelvis. The convex portion provides upright support for the thoracic spine. As a result, the occupant's S-shaped posture is maintained.

[0124] Explanation of reference numerals in the attached figures

[0126] 10, 10A: Chair

[0127] 20: Outer seat

[0128] 20A: Seat

[0129] 22, 22A: Upper end

[0130] 40: Outer backrest

[0131] 40A: Backrest

[0132] 42A, M42: Inclined surface

[0133] 60: Outer handrail

[0134] 60A: Handrail

[0135] 70, 70A: convex part

[0136] 72, 72A: first convex part

[0137] 74, 74A: Second convex part

[0138] 90: Buffer component

[0139] 91: First buffer component

[0140] 92: Second buffer component

[0141] 93: Third buffer component

[0142] 94: Fourth buffer component

[0143] 95: Cover component

[0144] 100: Chair body

[0145] 120: Inner seat

[0146] 140: Inner backrest

[0147] 160: Inner armrest

[0148] 200: First body component

[0149] 300: Second body component

[0150] L: Height position

[0151] N20: Outer seat surface

[0152] N60: Outer armrest surface

[0153] V1: Lower part of the scapula

[0154] V: Passenger

Claims

1. A chair, characterized in that including a chair body and a convex portion, wherein the chair body includes a backrest, the backrest includes a backrest surface, the backrest surface includes an inclined surface, the inclined surface is inclined rearwardly upward as toward an upper end of the backrest, the convex portion protrudes from the inclined surface and has a lower hardness than the chair body.

2. The chair according to claim 1, wherein the convex portion includes a first convex portion and a second convex portion, the first convex portion is disposed on the inclined surface and has a first resilience, the second convex portion is disposed on the first convex portion and has a second resilience, the second resilience is smaller than the first resilience.

3. The chair according to claim 2, wherein an upper end of the second convex portion is located on a lower side of an upper end of the first convex portion, a lower end of the second convex portion is located on an upper side of a lower end of the first convex portion.

4. The chair of any one of claims 1 to 3, wherein, a cover covering the convex portion and the entire backrest surface is further included.

Images