A sitting device

The present invention relates to a sitting device with a seat, the inclination of which may be changed relative to the support surface (e.g. the floor) for the sitting device, and having supporting means arranged for the knee- or calf-portion of the user below and substantially in front of said seat.

In the industrialized areas of the world one assumes a sitting posture too extensively, in other words, i.e. during a large portion of the day one has a posture providing an angle of approximately 90° between the legs and the torso. The hip joint has difficulty in accepting an angle in excess of approximately 50°, and the remaining 40° of angle is obtained by bending of the lowermost and soft portion of the spine. Upon forward bending for writing or other work, the stress on the spine becomes accordingly even greater. Such stresses are currently causing a lot of suffering in the back. In order to overcome these problems there has now been brought onto the market office chairs with a tiltable seat which may tilt forwardly and thereby increase the obtuse angle between the legs and the upper part of the body. According to the research done by the Swedish Furniture Institute, the disadvantage of these chairs are, inter alia,that the user easily may slide off the seat and therefore is unable to allow the said obtuse angle to increase by as much as would be desirable.

A prior art chair, known from US-patent 3.669.493, is adapted to support a person so that his weight is distributed between his posterior and his knee. The chair includes a knee support and a seat support sloping generally downward towards the knee support. The sloping seat and the knee support cooperate to shift a portion of a person's weight onto the knee support so that the weight borne by the person's posterior is reduced, thus permitting use of the chair over an extended period of time without the person developing a pain in his posterior. An arcuate lateral foot rest permits the person to place his feet in a number of positions.

The inclination of the seat may be changed and so may the inclination of the knee support. However, the chair is stationary on the floor and is difficult to enter, in particular with the embodiments having adjustable support for the seat and knees.

The present invention has therefore as an object to overcome the disadvantages related to chairs of the known types.

The sitting device according to the present invention is characterized in that the said supporting means are arranged at the front portion of the frame of the device in the form of two portions spaced apart in such a manner that there is free space between the portions, accessible from the front and in a direction towards the seat, the changing inclination of the seat being effected in conjunction with shifting of the legs of the user from a position in which the knees rest on the supporting means, to a position in which the calves of the user rest on the supporting means.

In one form of the invention the said supporting means are arranged at the front portion of the frame of the device in the form of two portions spaced apart in such a manner that there is free space between the portions, accessible from the front and in a direction towards the seat and the seat is hingedly connected to the said frame and forwardly tiltable.

In another form of the invention, the said supporting means are arranged at the front portion of the frame of the device in the form of two portions spaced apart from each other in such a manner that there is free space between the two portions, accessible from the front and in a direction towards the seat; the seat is fixedly connected to the said frame, the frame is provided with generally curved runners to rest against said support; and said supporting means are arranged at the front ends of said runners.

According to further features of the sitting device in accordance with the invention, the said generally curved runners may have, at a middle section, a bend about which the sitting device may be rocked to assume one of several possible stable positions in use. The supporting means have such position and inclination that the user upon resting either his knee or calf against these may place his feet against the support surfaces or said runners.

The sitting device is suitably provided with a back rest.

With the present construction the sitting device may be used as a conventional chair or stool, or as a chair with a tiltable seat, e.g. a rocking chair. When the desired angle between the legs and the torso is so wide that the user slides down from the seat, the knees or the calves are placed against the said knee- or calf-supporting means. The weight of the body will then be distributed between the seat and the knee- or calf-support so that it is possible to avoid sitting with muscles in the legs tensioned in order to prevent sliding off the seat. The angle between the torso and the legs in this posture, becomes approximately 135°; in other words even with relaxed muscles the lumbar region will not shoot backwards. The rocking construction has also the effect that, independently of whether or not his or her torso is balanced, the user may rock from the lumbar region and downwards and thereby obtain an active sitting method which makes the muscles of the hip joint active and in trim.

In order that the present invention may more readily be understood the following description is given, by way of example,of several specific embodiments of a seat in accordance with the present invention. Reference will be made to the accompanying drawings, in which:-

• Figures 1 to 6 illustrate a first embodiment of the sitting device according to the invention;
• Figures 7 to 12 illustrate a second embodiment of the sitting device according to the invention;
• Figures 13 to 18 illustrate a minor modification of the sitting device shown in Figures 1 to 6;
• Figure 19 shows a minor modification of the sitting device of Figures 7 to 12; and
• Figures 20 to 24 illustrate a third embodiment of the sitting device according to the invention.

Figures 1 to 6 show a sitting device 1 having a frame 2, curved runners 3 which are unitary with the frame seat 2, a seat 4 and knee or calf supporting means 5. In Figure 1 the sitting device is shown in a position where the torso and legs of the user form an angle of approximately 90°.

In Figure 2, the sitting device has been tilted so that the seat 4 is forwardly inclined and the calf portion of the user is then resting against the supporting means 5. In Figure 3, as well as in Figures 5 and 6, the user is shown using the supporting means 5 as a knee support.

As will appear from Figure 3, the runners 3 have a curved transition at 26 between substantially straight back and front portions 24 and 25 of the runners. The same feature is also indicated in Figure l5.

In Figures 7 to 12, the sitting device is illustrated as a rocking chair 6 where the frame 7 has continuously curved runners 8 which are unitarily connected with the frame 7. The seat 9 forms, with the back rest of the chair 10, an obtuse angle which is markedly greater than 90°.

On the front portions of the runners there is arranged a calf supporting means 11 comprising two spaced panels, in this case upholstered pads or cushions. As will appear from Figure 12, these calf supporting means 11 may also be used as a foot support when the sitting device is to be used as a conventional rocking chair.

Figure 8 illustrates how the position of the chair is altered when the seat is forwardly inclined relative to the support surface 12.

In Figure 9 the user sits at a table 13 and the supporting device serves as shown for supporting the calf portion of the user. The user has here, in the chosen example, placed the feet on the outside of the runners. However, the user may, as shown in Figure 10 arrange the feet on the inside of the runners.

In Figure 11 the sitting device is used as a conventional rocking chair. The same is the case in Figure 12, where, as pointed out above the supporting means 11 serve to support the feet of the user.

Figures 13 to 18 illustrate an embodiment of the sitting device according to the invention, which technically speaking, is identical to the embodiment of Figures 1 to 6. Instead of the somewhat solid frame 2 of Figures 1 to 6, there is here chosen a tubular frame, made for example from steel tubes 14. The form of the seat 15 and the supporting means 16 may of course be varied within the scope of the invention claimed. As pointed out in connection with Figure.3, there is a bend 26 between the substantially straight back and front portions 24 and 25 of the runners, thus causing a distinct curved transition at 26 between said sections. If desired the same may of course be the case for the embodiment shown in Figures 7 to 12 as well as for that shown in Figure 19 to be described below.

Figure 19 illustrates a modification of the second embodiment, i.e. the one shown in Figure 7 where the anchor - shaped frame is replaced by a t-shaped frame 17, in this case made from e.g. steel tubes. As in Figures 7 to 12, this embodiment is a rocking chair having continuously curved runners 18. The technical operation of the sitting device of Figure 19 is thus substantially identical to that described for the sitting device of Figures 7 to 12. From Figure 19 it appears, however, that the knee/calf supporting means 19 are arranged somewhat higher than in the embodiment of Figures 7 to 12. However, it will of course be readily understood that the supporting means may be arranged at any suitable distance from-the seat 20.

All of the above described embodiments of the sitting device in accordance with the present invention use generally curved runners. The preferred embodiments illustrated have generally curved runners falling into two distinct classes, namely on the one hand continuously curved runners conforming to an arc of a circle or of any other appropriate curve, and on the other hand dog leg runners having front and back substantially straight portions joined by a curved or a sharply defined transition.

Figures 20 to 24 represent a modification, in accordance with the present invention, of the prior art office chair discussed earlier. The operating principle of the office chair can be appreciated from Figures 20 and 21. The seat 21 is tiltable relative to a frame 23 of the chair about a hinge 22. In Figures 22 and 23 the user has placed his calf against the supporting means 24. In such a sitting posture the user is prevented from sliding off the seat. Although the sitting device of Figures 20 to 24 is shown as having straight floor-engaging base members instead of the generally curved runners of Figures 1 to 19, it will be within the scope of the present invention to use runners of the type illustrated in Figures 1 to 6 and in Figures 13 to 18, if desired.

There are, inter alia, two advantages by being able to alternate between the two illustrated sitting postures. These are, firstly that one avoids permanent stress on the same joints since it is disadvantageous to sit too long in the same posture, and secondly that the different postures are suited to different functions, for example normal posture for reading a book in one position and forwardly inclined work on a table in the other.

With the sitting device according to the present invention, as shown in Figures 7 to 12 and in Figure 19, there is provided a resting chair which is compatible with the requirements of a working chair. If it is desired to do something at a table, e.g. to eat, when sitting in a conventional deep arm chair, this will prove impossible. However, this problem is solved by using the comfortable rocking chair of the present invention and shifting the centre of gravity of the human body into an ergonomically correct working chair.

The adoption of a partly kneeling posture provides relieving of stresses and will, over a length of time, prevent certain back suffering. However, the sitting device of the present invention will also be well suitable for users who have so severe back complaints that they only can stand or lie, but not sit in a traditional manner.

All of the embodiments of sitting device illustrated in the accompanying drawings share the characteristic of having the knee- or calf-supports formed as two spaced panels, allowing access of the feet of the user between the two support parts in a direction towards the seat, i.e. rearwardly of the device. This facilitates positioning of the feet of the user in a comfortable position beneath the seat (either on the floor, or on the runners in the case of Figures 1 to 19 or the frame base member in the embodiment of Figures 20 to 24) with the knees or the calves resting on the two parts of the support.