The subject of the invention is an ergonomic seat that facilitates correct spinal position of the person sitting thereon, and that simultaneously provides comfort and ergonomic position while seating.

The invention relates to the sphere of preventive treatment of spinal diseases.

The natural posture of a human being is the upright posture. Sitting position is unnatural for us and can produce traumatizing situations for our organism. Therefore, the modern man, spending long hours daily in the sitting position, runs a risk of having problems with the movement system, especially with the spine. It is believed that it is the sitting position which is responsible for pandemic dimension of spinal diseases. Since incorrect, pathologenic posture while sitting is generally retained, spinal problems are more and more common diseases.

Statistical researches show that most lumbar disc herniations occur at the L5-S1 and the L4-L5 levels, namely, just above the incorrectly positioned pelvis. Meanwhile, the majority of solutions emphasise supporting of the lumbar region, leaving the pelvis vulnerable to the incorrect backward rotation.

There are known solutions of seats that take into consideration ergonomic functionality and that comprise hollow portions on their seating surface and supports for the lower region of the back.

The Polish patent application P-354570 discloses a seat destined for the use in sports buildings, movie theatres, public premises, and open space complexes. This solution provides a seat comprising a back support and a seating portion, which ends in the front with a downward, convex, curved flap.

Another solution known from the prior art is the seat presented in the utility model description U-110909, which comprises a seating body constituting a uniform board construction and having a hollowed seating portion and a rearwardly bent back portion, which are connected with an arch that sinks into the surface of the back portion.

Prior art also knows ergonomic solutions which take into account the bone construction of the user.

A solution comprising hollow portions to accommodate the ischial tuberosities was disclosed in the French patent document FR 2739008. It describes a seat adapted for receiving the ischial tuberosities of the user and having two transversely positioned grooves on its seating surface.

Moreover, the American patent application US 2004/005591 discloses an ergonomic seat comprising a specially shaped seating surface leaning at an angle from the back edge towards the front edge. Nonetheless, such seat does not solve the problem of a correct and simultaneously stable positioning of the spine in the sitting position which would moreover be comfortable.

DE 101 21 472 A1 is a known solution of the prior art which discloses a seat with self-adjusting properties and a method of manufacturing of the same. The self-adjusting seat, wherein "self-adjusting" particularly means that the seat adjusts in a manner dependent on the ambient boundary conditions of the load put on the seat, and on different user ergonomics in the scope of weight and its distribution. The disadvantage of this solution lies in the self-adjustment of the seat while forming the seating surface with use of the materials having ability to flow that adjust in an automatic way to the user's ergonomics, and as a result no constant spine thigh angle can be provided.

WO97/06713 document discloses a supporting seat, wherein the seat supports the pelvis of a user in a correct physiological position substantially corresponding to the pelvic standing position. The seat has a dished gluteal position which extends to the rear of the seat and a seat back with a substantially convex upper portion and a concave lower portion with the distance between the junction of the two and the lowest point of the dished gluteal portion substantially corresponding to the average dimension between the posterior superior spine of the ilia P and the ischial tuberosities (site bones) of an adult person.

According to this solution a seat comprises a seat bottom and a seat back which can extend substantially upright relative to the seat bottom, and the seat bottom has a raised front portion for tending to retain the user in the dished gluteal portion. The disadvantage lies in the raising front portion of the seat which promotes a position which may lead to discopathy.

Since the sitting position narrows the angle between the long axis of the spine and the long axis of the lower limbs, when we sit, we rest almost our entire body weight on the pelvis, which is directly connected with the spine via relatively immobile sacroiliac joints. Our ischial tuberosities are then especially encumbered. Simultaneously, the bending of the lower limbs leads to higher tension of the soft tissues around the hip joints and the pelvis, which fosters incorrect pelvis rotation toward counternutation - rearwards.

The aim of the invention is to develop a new construction solution of the seat so that harmful effects of the sitting position are minimised, or even eliminated, through stabilising the spinal lumbar region in an advantageous position and relieving the tender ischial tuberosities.

The ergonomic seat according to the invention comprising a specially shaped back support and a specially shaped seating portion is characterised in that the back support has a convexly shaped support for the lumbar region, which at the bottom is adjoining to the seating portion thus creating the adjoining line, whereas the upper surface of the seating portion is sloping towards the front of the seat at the angle α, and it comprises a rear oval hollow portion situated below the inclination line of the angle α. The angle α is preferably in the range of 2 to 15 degrees. The rear oval hollow portion constitutes from 1/3 to 2/3 of the length of the seating portion and preferably comprises a longitudinal depression, positioned centrally and corresponding to the oval axis, which relieves the ischial tuberosities.

According to one of the variants, the seat comprises a back support which only provides support for the lumbar region.

The upper surface of the seating portion and/or the lower portion of the specially shaped back support is/are lined with a resilient material, preferably silicone.

The invention also incorporates the use of the ergonomic seat as described hereinabove in every sitting structures.

And thus the invention incorporates the use of the seat in a school desk.

The use according to the invention incorporates also a sitting structure such as a sports seat, stadium seat, or a canoe seat.

Sitting structures for which the seat is found useful also comprise a chair, preferably an office chair, an armchair, preferably an office armchair, a car seat, an airplane seat, a conference armchair, a cinema/theatre armchair or seat, and a dental chair.

The seat can moreover be used as an overlay for a sitting structure.

The ergonomic seat, owing to the sloping position of its surface, retains an obtuse angle between the long axis of the spine and the long axis of the lower limbs. This seat, due to specially designed hollows and the resiliency of the material, absorbs pressure forces applied to the pelvis, relieving in particular the ischial tuberosities. A distinguishing sign of innovation of the solution is the profile of the junction between the support for the pelvis and the sacrum and the hollow portion of the seating portion, which prevents the counternutation movement and retains proper position of the pelvis and, consequently, of the spine. Such manner of joining the seat with the support for the pelvis and the lumbar region determines that the sitting position is ergonomic.

The ergonomic seat helps therefore retain proper position of the pelvis and the sacrum, and, consequently, proper spinal curvature, simultaneously providing comfort for the user, owing to the specially designed depression area relieving in particular the ischial tuberosities. Being longitudinal in shape, this depression allows for the possibility of a comfortable use of the seat by persons with varying spacing of the ischial tuberosities, which depends on the pelvis' size.

The subject-matter of the invention in its preferable example embodiment is shown in the drawing, where Fig. 1 presents a lateral cross-section of the ergonomic seat as seen from the side, and Fig. 2 - a top view of the seating portion of the ergonomic seat.

The ergonomic seat comprises a specially shaped back support adjoining to a specially shaped seating portion. The back support 1 has a convexly shaped support 2 for the lumbar region, which at the bottom is adjoining to the seating portion at the adjoining line 3. The upper surface 4 of the seating portion is sloping from the rear edge towards the front of the seat at the angle α, the seating portion comprising a rear oval hollow portion situated below the inclination line of the angle α. The angle α is approximately 7°. The rear oval hollow portion 5 constitutes approximately 2/5 of the length of the seating portion and it comprises a centrally positioned longitudinal depression to relieve the ischial tuberosities.

In one of the preferable example embodiments the back support is reduced to the convexly shaped support 2 for the lumbar region, which has the indicated profile.

The ergonomic seat can be useful in every type of the sitting structures, for example in a school desk, in chairs, armchairs and seats, such as an office chair, a sports chair, a stadium seat, a canoe seat, an office armchair, a car seat, an airplane seat, a conference armchair, a cinema/theatre armchair or seat, or a dental chair.

The seat can also be used as an overlay for a sitting structure.