Ergonomic seat

Abstract

An ergonomic chair (300) comprising a seat (310), a lower leg support (320), a chest support (330) and a hip support (360); the seat (310) is for supporting the back of the upper leg (11) and / or the half hip (12) of a seated user (10), the seat (310) is configured to push the hip of the seated user (10) in a forward direction; the lower leg support (320) is for supporting the front side of the lower leg (14) of the seated user (10); the chest support (330) is for supporting the chest (15) of the seated user (10) in a forward leaning position of the seated user (10); the hip support (360) is configured to support the front hip of the seated user (10) when the seat (310) pushes the hip of the seated user (10) forward towards the hip support (360).

Description

TECHNICAL FIELD

[0001] The present invention relates to an ergonomic chair. More particularly, the present invention relates to an ergonomic chair for use while performing work, gaming activities, creative activities, or any other situation where some type of fixed equipment or device is used. For example, the chair of the present invention can be used as a gaming chair, an office chair, or an artist's chair. The present invention is particularly useful for computer use, and particularly in combination with a screen display viewed by the user of the chair. BACKGROUND

[0002] In the following, the present invention and its advantages will be described in the context of such computer use. However, it should be noted that the present invention finds equal utility in corresponding fields of use, such as for general office work, writing, handicraft work, or in different types of simulators.

[0003] It is well known that sitting in a position that is not optimal from an ergonomic point of view for long periods of time can potentially lead to physical harm. In particular, the neck is exposed to such harm, for example due to the head of the person sitting bending forward and downward, in turn leading to muscle tension and related problems.

[0004] There have been many proposals for ergonomic chairs. For example, conventional office chairs come in a variety of configuration possibilities in terms of seat height and angle, back support, suspension, etc. There are ergonomic chairs with intentionally built-in imbalance, such as having only one leg or supported on an unstable base, thereby forcing the user to actively use core muscles to continuously balance the sitting position. There are ergonomic chairs without a backrest, thereby forcing the user to assume a correct upright position while sitting. There are even ergonomic chairs featuring a chest support instead of a back support, thereby allowing the user to lean forward instead of backward.

[0005] However, there are still problems with conventional ergonomic chairs. Many times, they are considered not comfortable enough for long periods of use, thereby leading to the user no longer continuing to use them. Moreover, they often do not provide the ergonomic benefits that they should provide, either because the actual sitting position is not optimal despite their good intentions, or because the user does not use them as intended.

[0006] Another problem with conventional ergonomic chairs is that they do not always encourage an "offensive" or "active" seating position. A relaxed, "passive" or "non-active" seating position or one in which the user is required to maintain some undesirable muscle tension will generally not provide the best user-perceived experience. When the correct, forward leaning and "active" seating position is assumed, the seated user will feel more active. Even so, such an "offensive" seating position will potentially result in improved reaction times and a more positive perceived engagement in the task being performed. This is particularly important for gaming when in many cases a small difference can determine the outcome. SUMMARY

[0007] The present invention solves the above-mentioned problems and provides an ergonomic chair having an ergonomically correct but offensive seating position. The chair of the present invention can also be manufactured in an efficient manner from standard materials and is aesthetically appealing.

[0008] The present invention thus relates to an ergonomic chair comprising a seat, a lower leg support, a chest support and a hip support;

[0009] The seat is for supporting the back of the thighs and / or the half of the buttocks of a seated user, the seat being configured to push the buttocks of a seated user in a forward direction;

[0010] The lower leg support is for supporting the front side of the lower leg of a seated user;

[0011] The chest support is for supporting the chest of a seated user in a forward leaning position of the seated user; and

[0012] The hip support is configured to support the front buttocks of a seated user when the seat pushes the buttocks of a seated user forward towards the hip support.

[0013] The present invention is characterized in that the seat has an area at the front end of the seat having a softer cushion than the rest of the seat in order to provide less pressure to the genitals of a male user of the seat, or

[0014] The seat has a recess at the front end in order to provide less pressure to the genitals of a male user of the seat.

[0015] Thus, the seat can be arranged to support the back of the thighs and / or the half of the buttocks of the seated user such that the femurs of the seated user are inclined in a forward direction at an angle of 40 to 75° relative to the horizontal, and the lower leg support is arranged to support the front side of the lower leg of the seated user, and the chest support is arranged to support the chest of the seated user in a forward leaning position of the seated user, and the hip support fixes the position of the user such that the third lumbar vertebra of the seated user is arranged in a support plane which is perpendicular to the sagittal plane of the user, and when the posture of the seated user is symmetrical about the sagittal plane of the seated user, the respective pivot points of the hip joints of the seated user and the respective pivot points of the shoulder joints of the seated user are also arranged in the support plane. BRIEF DESCRIPTION OF DRAWINGS

[0016] In the following, the present application will be described in detail with reference to exemplary embodiments of the application and the accompanying drawings, in which:

[0017] Figure 1a is a schematic side view of an ergonomic seat according to an exemplary embodiment;

[0018] Figure 1b shows an ergonomic seat with a person seated thereon; Figure 1a

[0019] Figure 1c shows an ergonomic seat according to the present application Figure 1b and also with certain angles, shown in

[0020] Figure 2a is a perspective view of an ergonomic seat according to an exemplary embodiment;

[0021] Figure 2b is a side view of an ergonomic seat Figure 2a

[0022] Figure 2c is a front view of an ergonomic seat Figure 2a

[0023] Figure 2d is a rear view of an ergonomic seat Figure 2a

[0024] Figure 2e is a top view of an ergonomic seat Figure 2a

[0025] Figure 3 shows an exemplary chest support corresponding to the chest support shown in Figures 1a to 1c , Figures 2a to 2e DETAILED DESCRIPTION ​​​​​​

[0026] In all the figures, the last two digits in each reference number are used to indicate identical or corresponding details. The figures are not necessarily drawn to scale.

[0027] Figure 1a and Figures 2a to 2e An exemplifying embodiment of an ergonomic chair 100, 300 according to the present application is shown in the respective views. The ergonomic chair 100, 300 comprises a seat 110, 310, a lower leg support 120, 320, a chest support 130, 330 and a hip support 160, 360.

[0028] In the following, the function will be described with reference to Figure 1a and Figure 1b which figures show a seated person on the chair 300. Figures 2a to 2e Corresponding parts of the chair 100, 300 are also added to the discussion regarding Figure 1b and Figure 1c . Figure 1b An ergonomic chair 100, 300 with a seated user 10 is shown. In the figure, the user 10 is shown in a seated position in which the user is seated in an ergonomically advantageous position made possible by the specific geometry of the ergonomic chair 100, 300 in question, as will be explained in the following.

[0029] In particular, the seat 110, 310 is arranged to support the back of the thighs 11 and / or the half buttocks 12 of the seated user 10 and is configured to urge the buttocks of the seated user 10 in a forward direction towards the hip support 160, 360, which is configured to support the front buttocks of the seated user 10, such that the femur 13 of the seated user 10 is inclined in a forward direction at an angle Al of at least 40°, more preferably at least 50°, and at most 75°, more preferably at most 65°, relative to the horizontal. This is best shown in Figure 1c , where the various angles described herein are shown. This femur position and inclination can be achieved, for example, by the inclined seat 110, 310 described below and the relative geometrical arrangement between the seat 110, 310, the lower leg support 120, 320, the chest support 130, 330 and / or the hip support 160, 360.

[0030] In addition, the lower leg support 120, 320 is arranged to support the front side of the lower leg 14 of the seated user 10, while the chest support 130, 330 is arranged to support the back of the chest 15 of the seated user 10, in a position in which the seated user 10 is in an upright position, as shown in Figure 1b , Figure 1cThe forward leaning position of the user 10 shown in Fig. 1 supports the chest 15 of the seated user 10. This forward leaning position is created due to the combined geometry of the seat 110, 310, the lower leg support 120, 320, the chest support 130, 330 and the hip support 160, 360 in relation to each other due to the user 10 sitting down into the ergonomic chair 100, 300. Thus, the ergonomic chair 100, 300 is arranged to force or even compel the user to adopt said forward leaning posture by the relative geometry of its constituent parts when the user 10 is seated in the ergonomic chair 100, 300.

[0031] The seat 110, 310, the lower leg support 120, 320 and the chest support 130, 330 can optionally be fixedly arranged in relation to each other, such as by metal rods or in any other suitable way. In other words, the support points can be fixedly arranged in space in relation to each other. However, the hip support 160, 360 is preferably movable upwards and downwards so that it can be set to be at a level on top of the front side of the seated user's 10 thighs. The hip support 160, 360 can preferably be fixed in different vertical positions.

[0032] It is desirable that the seated user 10 when in said forward leaning position is oriented so that the third lumbar vertebra body 16 of the seated user 10 is arranged in Figure 1c In the support plane 350 shown in Fig. 1, which is perpendicular to the sagittal plane of the seated user 10. Thus, in Figure 1c In Fig. 1, the support plane 350 is perpendicular to the paper.

[0033] Further, when the posture of the seated user 10 is symmetrical about the sagittal plane of the seated user 10 in the forward leaning position, the respective pivot points 17 of the hip joints of the seated user 10 and the respective pivot points 18 of the shoulder joints of the seated user 10 are also arranged in said support plane 350. This property of the forward leaning position is achieved by combining the position and angle of the femur 13 of the seated user 10 and the position of the chest support 130, 330 point.

[0034] It can be understood that in Figure 1c In Fig. 1, the sagittal plane of the seated user 10 is parallel to the paper, resulting in Figure 1c However, according to the present invention, when the seated user 10 is positioned in said forward leaning position supported by the ergonomic chair 100, 300, both the hip joint pivot points 17, both the shoulder joint pivot points 18 and the third lumbar vertebra body are arranged in said support plane 350.

[0035] The inventors have found that a seat with a support plane 350 in which the aforementioned position with the anatomical details 16, 17, 18 of the seated user 10 is adopted, as a result of the relative geometrical positioning of the different support structures 110, 120, 130, 160, 310, 320, 330, 360, offers an ergonomically very advantageous sitting experience. The seated user 10 can fully relax while at the same time maintaining a very low level of disruptive tension and at the same time maintaining an active posture, which in turn leads to an increased attention to the task at hand.

[0036] In particular, for ergonomic reasons, it is preferred that the forward leaning position is such that the femur 13 of the seated user 10 is tilted in a downward direction with respect to the horizontal at an angle Al of at least 40°, more preferably at least 50°, at most 75°, more preferably at most 65°, in a forward direction.

[0037] In an ergonomically preferred embodiment, the support plane 350 is tilted with respect to the horizontal at an angle A2 of at least 65°, preferably at least 70°, at most 90°. The angle A2 can be in the range of 75 to 90°, but can also be in the range of 80 to 90°. The angle A2 can also be at most 85°.

[0038] In addition, the inventors have found that the aforementioned positive ergonomic effects can be more effectively achieved in the preferred case in which the ergonomic seat 10 does not comprise a head support. This is shown in Figure 1c which the ergonomic seat 100, 300 does not comprise a head support. Such a head support can for example be a neck, chin, temple or forehead support. Preferably, the head of the seated user 10 is not supported at all, such that the seated user 10 needs to rely entirely on him or herself to balance his or her head. Given the orientation of the seated user 10 in the aforementioned support plane 350, assuming the forward leaning position described herein, the balancing of the head will typically result in the user orienting his or her head such that the line of sight of the seated user 10 is oriented horizontally, in turn resulting in an ergonomically advantageous sitting position of the user 10.

[0039] The seat 110, 310 preferably has a seating surface 111, 311 that is tilted forwardly downwardly to push the buttocks of the seated user 10 in a forward direction.

[0040] The angle A3 determines the angle of the seating surface 111, 311 that ultimately supports the half buttock 12 or the back of the thigh 11 of the seated user 10, and thus also influences the position of the seated user 10, such as the femur 13 in the aforementioned forward leaning position.

[0041] In particular, it is preferred that the seating surface 111, 311 is inclined forward and downward (with respect to the seated user 10) by an angle A3 comprised between 1° and 20° (preferably between 1° and 15°, more preferably between 3° and 12°) with respect to the horizontal, depending on the specific case.

[0042] In one example, the seating surface 111, 311 is not inclined with respect to the horizontal.

[0043] Generally, in the forward leaning position, it is preferred that the majority of the weight of the seated user 10 is supported by the seat 110, 310, as opposed to the lower leg support 120, 320 or the chest support 130, 330. This is achieved by the relative geometrical arrangement between these parts, as described herein and exemplified in the drawings.

[0044] Preferably, the ergonomic chair 100, 300 does not comprise any other seated user 10 load support part, in addition to the seat 110, 310, the lower leg support 120, 320, the chest support 130, 330 and the hip support 160, 360 for supporting the seated user 10 in said forward leaning position.

[0045] With respect to the lower leg support 120, 320, it is preferred that this part is arranged in such a way that the lower leg 14 of the seated user 10 is substantially horizontally oriented, further preferably so that the shin 20 of the seated user 10 is inclined upwardly from the knee of the user 10 with a non-zero angle A4 with respect to the horizontal, which angle A4 can preferably be comprised between 0° and 10° upwardly from the knee of the user 10.

[0046] In addition, the ergonomic chair 100, 300 can further comprise armrests 340, which are arranged to support the elbows or lower arms of the seated user 10 in the height and position of the seated user 10 with relaxed shoulders when in said forward leaning position. Preferably, the upper arms of the seated user 10 can be vertical or slightly forwardly downwardly inclined. Then, the lower arms of the seated user 10 are preferably arranged substantially horizontally. In this position, the handling of a keyboard, computer mouse, etc. is possible in an ergonomically good way.

[0047] As an alternative to armrests, a table top can be integrated to the frame 170; 300 of the chair 100, said table top being in front of and above the hip support 160, 360.

[0048] With respect to the hip support 160, 360. As Figures 2a to 2eThe hip support 160 has a support area 161a, 162a on each side of the seat 100, as shown by way of example. These are intended to support the front hip of a seated user, in particular its anterior superior iliac spine. Thereby, the front hip of a seated user can be supported by the support areas 161a, 162a when the seat 110 pushes the hip of the seated user forward. The support areas 161a, 162a are located on a respective hip support arm 161, 162 which each extends laterally on a respective side of the seat 100 and in an upright position above the seat 110. As already mentioned, the hip support 160, 360 is preferably movable upwardly and downwardly, so that it can be set to be at a level on top of the front side of the thigh of a seated user. Thereby, the position relative to the seat 110 is fixed. Figure 3 b and Figure 3 c depict the desired position.

[0049] Further, with regard to the hip support 160, 360, as Figure 2a indicated by the double-headed arrow in the middle, in some embodiments, the hip support arms 161, 162 are vertically displaceable, such as foldable or upwardly / downwardly movable. For example, the hip support arms 161, 162 can be coupled to the frame 170 using a pivot joint or a vertically movable joint, such as using a block in a vertical rail. Thus, in order to enter the seat, the user can lift / pivot the hip support arms 161, 162 upwardly, sit on the seating surface 111, 311 and lower the hip support arms 161, 162 again onto the user’s legs in order to assume the seating position. It is to be understood that the support areas 161a, 162a then also move upwardly / downwardly with the hip support arms 161, 162. Preferably, the hip support arms 161, 162 are not locked in the lowered position, so that they are freely movable / pivotable upwardly / downwardly when the user is seated in the seating position. That is, it has proven that such movable hip support arms 161, 162 provide a more ergonomic seating experience when sitting during long periods of time, as they allow the user to fine-tune the seating position and move around on the seat to some extent.

[0050] With regard to the leg support 120, 320. As Figures 2a to 2e shown by way of example, the leg support 120 can comprise laterally extending arm sections 121, 122 on each side of the seat. Optionally, the laterally extending arms 121, 122 of the leg support can be folded such that the arm sections 121, 122 extend along a central longitudinal line of the seating furniture to enable a seated user to use the seat without using the leg support. Optionally, the leg support 120 can be movable forwardly and backwardly along the central longitudinal line to adjust its position. ​

[0051] Further, with respect to the leg support 120, 320, and also as Figure 2a In some embodiments, the arm segments 121, 122 can be pivotable or rotatable in a horizontal plane between said lateral orientation and said longitudinal orientation, as indicated by the double-headed arrow. Preferably, this pivoting or rotation is not limited, so that a seated user can swing his or her legs resting on the segments 121, 122 back and forth by rotating the leg support 120, 320 in the horizontal plane. This has proven to be very advantageous from an ergonomic point of view, as it allows the user to move without losing the ergonomically correct position automatically defined by the different parts of the seat described herein.

[0052] In a particularly preferred embodiment, both the hip support arms 161, 162 and the leg support portions 121, 122 are freely movable, as described above. This provides a relatively free movement for a seated user, without losing the ergonomically advantageous sitting position provided by the inventive seat.

[0053] With respect to the seat 110, 310. As Figures 2a to 2e The seat 110 is wider at the rear end of the seat 110 than at the front end of the seat 110, as illustrated by the example. Further, the width of the seat 110 narrows gradually from the rear end of the seat 110 towards the front end of the seat 110. The seat 110 has an arcuate longitudinal cross-section with an increasingly smaller arch in the forward direction, thereby providing a saddle shape of the seat 110, 310. The shape of the seat 110 helps to push the hips of a seated user in the forward direction.

[0054] The seat 110 has an area 112 at the front end of the seat 110 with a softer cushioning than the rest of the seat 110, in order to provide less pressure to the genitals of a male user of the seat 110. The softer cushioning can be provided, for example, by a certain volume of less firm material at the front end of the seat 110, or by an internal void at the front end of the seat 110, for example. As an alternative, the seat 110 can have a recess at the front end of the seat 110, in order to provide less pressure to the genitals of a male user of the seat 110. Such softer cushioning or void can be arranged only at the front end of the seat, or can also extend backwards along the centre line of the seat 110, such as at least 10 cm backwards, or at least 20 cm backwards, or even along the entire longitudinal length of the seat 110. For example, the seat 110 can form a cross-sectional shape similar to the letter "M" in a series of vertical cross-sections taken at different positions along the seat 110, starting at the front end of the seat 110 and going backwards.

[0055] The seat can be provided with a cushioning layer such that it has at least two cushioning layers stacked, an outermost layer closest to the back of the thighs and / or the half of the buttocks of the seated user and an innermost layer for attachment to the frame of the seat 100, each layer having a different firmness as measured by the indentation load deflection.

[0056] The layers are preferably arranged with a higher firmness in the innermost layer of the seat and a decreasing firmness of each layer towards the outermost layer. Preferably, at least one of the layers comprises a solid foam, preferably a polymer foam. All layers can be solid foams, in particular polymer foams, of different firmness. In one embodiment, the number of foam layers is three.

[0057] Figure 3 A more detailed illustration of the chest support 430 corresponding to the chest support 130, 330 shown in Figures 1a to 1c 、 Figures 2a to 2e The chest support 430 is associated with a concave shape 431 (comprising a surface having a concave shape) according to the invention, which is arranged complementary to the corresponding convex shape of the chest 15 of the seated user 10 and in particular to the convex shape of the chest 15 of the seated user 10 when the seated user 10 in question is oriented in the forward leaning position along the support plane 450 described above. This concave shape 431 thus, in combination with the orientation of the above described support parts 110, 120, 130, 310, 320, 330 of the ergonomic seat 100, 300, prompts or even forces the seated user 10 to assume the above described forward leaning position along the support plane 450. The concave shape 431 can be a developable or non-developable surface.

[0058] In particular, the concave shape 431 comprises a concave curvature in a vertical cross-sectional plane, which is preferably the sagittal plane of the seated user, having a radius of curvature 432 between 2 and 3 meters.

[0059] As shown in Figure 2a The seat 100 preferably has three contact points or feet 171a, 171b, 171c. The seat 100 can also have four such contact points, even though preferably three contact points are present. In addition, two of these contact points 171a, 171b are advantageously arranged to contact the floor on which the seat 100 stands at two different contact points arranged in front of the center of mass of the seat 100 and preferably also in front of the center of mass of the seated user. If three contact points are present, the third contact point 171c can be arranged behind the first two contact points 171a, 171b, behind the center of mass.

[0060] Furthermore, the seat can comprise a base structure, which is arranged in the center of mass of the seat 100 and which is arranged to be in contact with the floor on which the seat 100 stands. Figure 2aIn the middle, three arms 172 are shown extending from the common point to each of the foot portions 171a, 171b, 171c. Alternatively, the base structure can comprise a horizontal plate. The rest of the frame 170 can then be connected to the common point, in Figure 2a In the middle, a substantially vertical pole 173 is shown extending upwardly from the common point on the base structure.

[0061] The base structure comprising the arms 172 is preferably made of metal or wooden material, providing a certain elasticity. The two front floor contact points 171a, 171b are preferably arranged at least 40 cm apart. In case of two rear floor contact points, they are preferably arranged at most 20 cm apart from each other. This configuration has proven to provide the user with the possibility to move his or her center of gravity to some extent from side to side, making it possible to sit comfortably for a longer period of time without leaving the ergonomically correct sitting position created by the seat 100. This is particularly the case for a seat as described above with three contact points 171a, 171b, 171c. More particularly, when combining such a base structure with the movable hip support arms 161, 162 and / or leg supports 120, 320 discussed above, the seat 100 will allow the user to make small movements while sitting in the seat 100, which movements allow the user to sit comfortably for longer without leaving the ergonomically advantageous sitting position described herein.

[0062] Above, a preferred embodiment has been described. However, it will be clear to the skilled person that many modifications can be made to the disclosed embodiment without departing from the basic idea of the present invention.

[0063] In general, all of the above-described embodiments can be combined in any applicable way.

[0064] In addition to the design features described above and shown in the drawings, the ergonomic seat 100, 300 can comprise many other design features, as long as the principles described herein regarding the forward leaning position of the seated user 10 are followed.

[0065] In particular, the ergonomic seat 100, 300 can be adjusted in various ways in order to accommodate users 10 of different length, weight and other physical characteristics.

[0066] The ergonomic seat 100, 300 can also comprise cushions and other features that improve the comfort of sitting.

[0067] The present invention is therefore not limited to the described embodiments, but can vary within the scope of the appended claims.

Claims

1. An ergonomic seat (100; 300) comprising a seat (110; 310), a lower leg support (120; 320), a chest support (130; 330) and a hip support (160; 360); the seat (110; 310) is for supporting the back of the thighs (11) and / or the half buttocks (12) of a seated user (10), the seat (110, 310) being configured to push the buttocks of the seated user (10) in a forward direction; the lower leg support (120; 320) is for supporting the front side of the lower leg (14) of the seated user (10); and the chest support (130; 330; 430) is for supporting the chest (15) of the seated user (10) in a forward leaning position of the seated user (10); the hip support (160; 360) comprises two hip support arms (161; 162) on opposite lateral sides of the seat (100), the hip support arms (161; 162) each having a respective support area (161a; 162a), the support areas (161a; 162a) each being configured to support a respective anterior superior iliac spine of the front buttocks of the seated user (10) when the seat (110; 310) pushes the buttocks of the seated user (10) forward to the hip support (160; 360); the seat (110; 310) has an arcuate longitudinal cross-section providing a saddle shape of the seat (110; 310), and the seat has an area (112) at a front end of the seat (110; 310) having a softer cushion than the rest of the seat (110; 310) in order to provide less pressure to the genitals of a male user (10) of the seat (110; 310), or the seat has a recess at the front end (110a) in order to provide less pressure to the genitals of a male user (10) of the seat (110; 310).

2. The seat (100; 300) according to claim 1, wherein The hip support arms (161; 162) are vertically displaceable or pivotable.

3. The seat (100; 300) according to claim 2, wherein The support areas (161a, 162a) are located on the respective hip support arms (161, 162) laterally extending on the respective side of the seat (100, 300) and in a vertical position above the seat (110; 310).

4. The seat (100; 300) according to any one of claims 1 to 3, wherein, The seat (110; 310) has a forwardly downwardly inclined seating surface (111; 311) to push the buttocks of the seated user (10) in a forward direction.

5. The seat (100; 300) according to claim 4, wherein The forwardly downwardly inclined seating surface (111; 311) is inclined with respect to horizontal at an angle (A3) in the range of 1° to 20°.

6. The seat (100; 300) according to claim 4, wherein The forwardly downwardly inclined seating surface (111; 311) is inclined with respect to horizontal at an angle (A3) in the range of 1° to 15°.

7. The seat (100; 300) according to claim 4, wherein The forwardly downwardly inclined seating surface (111; 311) is inclined relative to horizontal at an angle (A3) in the range of 3° to 12°.

8. The seat (100; 300) according to any one of claims 1 to 3, wherein, The seat is wider at a rear end (110b) of the seat than at a front end (110a) of the seat.

9. The seat (100; 300) according to any one of claims 1 to 3, wherein, The width of the seat tapers from a rear end of the seat towards a front end of the seat.

10. The seat (100; 300) according to any one of claims 1 to 3, wherein, The arcuate longitudinal cross-section has an increasingly smaller arch in the forward direction.

11. The seat (100; 300) according to any one of claims 1 to 3, wherein, The softer cushion is provided by a volume of less firm material at the front end of the seat (110; 310).

12. The seat (100; 300) according to any one of claims 1 to 3, wherein, The softer cushion is provided by an internal void at the front end of the seat (110; 310).

13. The seat (100; 300) according to any one of claims 1 to 3, wherein, The seat is layered such that it has at least two cushion layers superposed on each other, an outermost layer closest to the seated user's (10) posterior thighs (11) and / or half buttocks (12) and an innermost layer for attachment to a frame (170) of the seat (100; 300), each layer having a different firmness.

14. The seat (100; 300) according to claim 13, wherein The layers are arranged with a higher firmness in the innermost layer of the seat and a decreasing firmness of each layer towards the outermost layer.

15. The seat (100; 300) according to any one of claims 1 to 3, wherein, The calf support (120; 320) comprises laterally extending arm sections (121, 122) extending laterally on each side of the seat.

16. The seat (100; 300) according to any one of claims 1 to 3, wherein, The hip support (160; 360) is configured to support the seated user's (10) front hip such that the seated user's (10) femur (13) is inclined relative to horizontal at an angle between 40° and 75° downward in the forward direction of the seated user (10).

17. The seat (100; 300) according to any one of claims 1 to 3, wherein, A forward leaning position is achieved by the combination of the position and angle of the seated user's (10) femur (13) and the position of the chest support (130; 330), the forward leaning position being oriented such that the seated user's (10) third lumbar vertebra (16) lies in a support plane (350) and the respective pivot point (17) of the seated user's (10) hip joint and the respective pivot point (18) of the seated user's (10) shoulder joint also lie in the support plane (350) when the seated user's (10) posture is symmetrical about a sagittal plane of the seated user (10) in the forward leaning position, the support plane (350) being perpendicular to the seated user's (10) sagittal plane, the support plane (350) being inclined relative to horizontal by 75° to 90°.

18. The seat (100; 300) according to any one of claims 1 to 3, wherein, The chest support (430) comprises a concave shape (431) arranged to complement a corresponding convex shape of the seated user's chest (15).

19. The seat (100; 300) according to claim 18, wherein The concave shape (431) comprises a concave curvature in a vertical cross-section.

20. The seat (100; 300) according to claim 19, wherein The concave curvature in the vertical cross-section has a radius of curvature (432) between 2 meters and 3 meters.

21. The seat (100; 300) according to any one of claims 1 to 3, wherein, The calf support (120; 320) is arranged such that the seated user's (10) calf (14) is oriented substantially horizontally.

22. The seat (100; 300) according to any one of claims 1 to 3, wherein, The lower leg support (120; 320) is arranged such that the tibia (20) of the seated user (10) is inclined between 0° and 10° upwards from the knee of the seated user (10) with respect to horizontal. The lower leg support (120; 320) is arranged such that the tibia (20) of the seated user (10) is inclined between 0° and 10° upwards from the knee of the seated user (10) with respect to horizontal.

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