Chairs and seats – Movable bottom – Tiltable
Reexamination Certificate
1999-04-21
2001-04-10
Cranmer, Laurie K. (Department: 3636)
Chairs and seats
Movable bottom
Tiltable
C297S195100, C297S215150
Reexamination Certificate
active
06213553
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a seat element, and more particularly to a bicycle seat, the bicycle seat being especially suitable for mountain and road bikes.
2. Description of Prior Art
As a result of the increasing number of activities which are practiced when seated, such as for example desk work or protracted periods of traveling in a motor vehicle, the complaints resulting from back pain have increased considerably in the last years. The main cause for the occurrence of these complaints are incorrect seating elements which bring about an incorrect sitting position.
However, the occurrence of back pains can also not be fully prevented even by orthopedically correctly shaped seats and a correct sitting position. A correct sitting position can also lead to back problems if this correct sitting position is rigidly maintained for too long a period, i.e. without movement of the spine. Since the intervertebral discs only alternately suck up nutritious liquid and discharge liquid depleted of nutrition with a movement of the spine, an adequate supply of the discs is also not present with a rigid seating position. Accordingly, a correct sitting position can lead to an undersupply of the discs if it is maintained rigidly over a long period of time, and can thus lead to premature wear with the corresponding complaints.
Non-traumatic pain syndromes experienced by bicyclists are the most common type of pain syndromes experienced by bicyclists. For example, at the 1976 Bikecentennial Tour, a sample of 89 cyclists were interviewed and all experienced saddle soreness, and more particularly, 9% had severe symptoms including marked saddle soreness while 7% had crotch numbness. Recently, 86% of 132 cyclists participating in a 500 mile long tour reported symptoms experienced from the ride and 64% experienced buttock pain. The rate of buttock pain exceeded the rate of nearly all of the other related symptoms and 52% of those with buttock pain required a change in riding style or a temporary cessation of cycling.
Typically, up to 72% of cyclists experience pain, redness and tenderness of the skin overlying the ischial tuberosity, which then increases with riding time and can progress to skin ulceration. It is believed that the mechanism of injury is probably a combination of sheering forces and pressure that causes necrosis. Additional prophylactic padding on the saddle and the use of well-padded bicycle pants over the ischial tuberosity as well as the use of a seat that is a few inches wider than the distance between the ischial tuberosities has been suggested.
During cycling, the pelvis moves from one side to the other. High friction and insufficient padding over a certain amount of time result in the aforementioned buttock pain and skin ulceration.
SUMMARY OF THE INVENTION
The present invention provides a seat element comprising a base unit and a seat surface which has a front edge and a rear edge, with at least a part of the seat surface being tiltable relative to the base unit about at least one main axis, wherein the main axis extends from the front to the rear edge of the seat surface, wherein the main axis is arranged spaced by a maximum of 10 cm from the seat surface, wherein the tilting angle of the tiltable part of the seat surface is restricted to a maximum tilt angle and wherein the maximum tilt angle amounts to at most ±15° relative to the central position of the tiltable part of the seat surface.
Through the seat element formed in accordance with the invention a situation is achieved in which the lumbar segments of movement of the spine are in motion when sitting, so that the intervertebral discs can pick up adequate nutrients. As a result of the tilt axis extending from the front edge to the rear edge of the seat surface a lateral tilting movement of the pelvis is achieved, which, on the one hand, is perceived as unobtrusive and particularly pleasant, and on the other hand, enables an ideal movement of the lumbar vertebrae and thus an ideal supply of the intervertebral discs.
It is important that, on the one hand, the tilt axis is arranged as closely as possible to the ischial tuberosities of a person sitting on the seat element, and, on the other hand, that the maximum tilt angle is restricted to a relatively low value.
Through the said arrangement of the tilt axis it is ensured that at the same time as the pelvis is tilted only a very small or indeed no lateral displacement of the pelvis occurs. A lateral displacement of this kind would in particular cause an increased pelvic tilting with a spine fixed in an eventually present backrest and would thus increasingly move the lower lumbar segments of motion. In this way extents of movement would be achieved which approach the passive maximum extent of movement and would thus lead to increased ligamentary disc stresses, which can be perceived as unpleasant and thus reduce or negate the desired effect.
The restriction of the maximum tilt angle is important for the invention because an overextension of the spine and also overextensions of the capsules of discs must be avoided. The tilting movement may not therefore take place between the maximum possible tilt angles for a particular person but must rather lie in a physiologically reasonable range. An overextension of the spine and of the corresponding discs would lead to low back pains and thus run contrary to the sense of the invention. Extreme positions which are indeed possible, but which are, however, perceived to be unpleasant, or are even dangerous in the long term, are effectively avoided by restricting the tilt angle.
A further advantage of the invention lies in the fact that through the tilting of the pelvis in only a small angular range the movements of the lower lumbar vertebral column can be compensated for by corresponding countermovements of the upper lumbar vertebral column. In this way no or only slight movements of the thoracic spine occur so that the stability when seated is retained. This is in particular of importance when using a seat element formed in accordance with the invention in a motor vehicle.
In accordance with an advantageous embodiment of the invention the maximum tilt angle is adjustable. This ensures that the extent of the movements of the spine associated with the tilting can be ideally matched to the particular person. For elderly people in particular the mobility of the spine is restricted so that for such people the maximum tilt angle must be reduced relative to the maximum tilt angle for younger people. If this was not done, overextensions of the capsules or discs would occur as a result of the bending of the spine being too large and would lead to back pains. Accordingly, an ideal adaptation of the seat element formed in accordance with the invention to the physiological characteristics of different persons is possible through the adjustability of the maximum tilt angle.
In accordance with a further preferred embodiment of the invention, restriction elements are provided which restrict the maximum tilt movement of the tiltable part of the seat surface. In this manner a particularly simple and cost-favorable design of the restriction of the maximum tilting movement is possible. In particular the restriction elements can be adjustable in order to thereby achieve the adjustability of the maximum tilt angle. The restriction elements can in this respect also be so differentially adjustable that the maximum tilt angle in one tilt direction has a different magnitude in comparison to the maximum tilt angle in the opposite tilt direction. The maximum tilt angle can, however, also be of the same size in both directions of tilting.
The restriction elements are preferably made resilient for the damped restriction of the maximum tilting movement, so that an abrupt restriction of the tilting movement, which would stress the spine, is avoided. For this purpose the restriction elements can, for example, be formed of resilient material, such as rubber or plastic, or springs, or can be supported in
Cranmer Laurie K.
Hale and Dorr LLP
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