The present invention relates to an adjustable seat support structure or device that is used to support the weight of a person, in particular a seated person and especially to an adjustable support structure or device, that is adjustable so as to alter the seating or reclining position of a subject resting on the structure. The background to the invention will therefore be described in the next section of this specification with specific reference to an office chair.

Background to the Invention

There are many situations where there is a need to provide an adjustable seating support structure. One of the best-known but not exclusive examples of this need is in office chairs, where the posture of a seated person needs to be altered, in order to administer various tasks executed in a seated position. It also needs to be altered in terms of height, build and proportions of the seated person. Yet again, the person’s seating or reclining position may need to be altered, to provide a higher seating position in tandem with a height adjustable table or desk. Examples shown in Pat. US20120299350, Pat. US20090140567, Pat. EP 94/02642.

Support structures for use in offices and other situations, which allow altering the seat height, seat inclination and reclining position of a subject are known, (Pat. US 93/05731, Pat. US7806478, Pat. US 2008/052208, Pat. US 2005/024213, Pat. US8944507). However, many of the known forms of support structures suffer from some disadvantages, either by not acknowledging the current status of biomechanical science or focus only on some limited parts of the ergonomic implications of the seated person. The current embodiment of the invention is primarily, but not exclusively, focused on an office chair application.

Office chairs are known to comprise at least five portions:

(A) A mobile base support portion

(B) An adjustable support structure portion (mechanism)

(C) A seat support portion (seat pan)

(D) An arm support portion (armrest)

(E) A back support portion (backrest)

Portion (A) supports the upper portions (B, C, D & E), can be equipped with glides or swiveling wheels for mobility while seated and may contain a mechanical or pneumatic device to allow a height adjustment of the four upper portions. Portions (B) and (C) form the heart and center of this invention and enable an articulated movement of a seated person from a forward leaning position to a backward relaxing position, which can be secured in infinite by the use of frictional mechanical and/or pneumatic means.

Portion (D) is attached to and follows the backrest so as to maintain a constant equal and proportional correct height for the lower arm of a seated person.

Portion (E) is configured to be pivotally hinged to portion (C) to allow for a reverse synchronized alteration of the backrest, e.g. lumbar support, with the imaginative pivotal fulcrum in the hip joint.

Many known forms of support structure, upon which a user may be supported in a seated position, demonstrate limited knowledge of the current state of anthropological or biomechanical data or purposely choose to focus only on parts of it. For example, we see continuously chairs, which suffer from the following deficiencies:

despite current knowledge and scientific fact, a majority of manufacturers still follow an outdated rule of sitting upright at fixed 90-degree angles between leg, thigh and upper body (torso). Scientific evidence (Mandal, Keagan) shows, that the angle between the vertical axis of the pelvis and thighs at the hip joint can only bend 60 degrees; the remaining 30-degree bending is effected by commensurate rotation of the pelvis axis backwards, which changes the natural curve of the spine (lordosis) into an opposite curve (kyphosis), which causes asymmetric pressure on the inter-vertebrae discs, which are squeezed outwards. Although the spine can be forcefully pushed back into its natural curve with an outspoken lumbar support, this will eventually cause discomfort and back pain, because the muscles of the lower back, the buttock muscles and lower muscles of the thigh are subjected to prolonged static load, which can result in acidosis in these muscles and pain symptoms. The lack of movement will eventually result in unsufficient synovial fluid, which serves to lubricate the lower vertebrae and the intervertebral discs; in some support structures all the individual surfaces, that make up the ergonomic platform, must be secured into position in sequences, often with readjustments required, making the transition from one support position (e.g, a reclining position) to another (e.g., an upright seating position) cumbersome and time consuming;

the majority of products currently in the market do not match with the long established requirement and regulations in many countries of height adjustable tables, which demand a flexible workplace solution to offer a table height for either working while sitting down or standing up without a chair entirely;

many products currently in the market also do not offer alternative applications of their use for example in industrial, medical or other fields of an ergonomic support structure; A need therefore exists for an adjustable support structure which addresses one or more of the above problems associated with the prior art.

The present invention aims to provide a support structure, which recognizes and supports the current state of anthropological and biomechanical facts.

Furthermore, the current invention aims to allow and to encourage a‘seated’ person into shifting the seating position upward in a convenient and often - in an easy understandable and a self-explanatory way.

Summary of the Invention

The present invention generally provides a support structure for supporting a person in a seated position, the support structure comprising:

a linear for- and upward or back- and downward moving apparatus to carry the weight of a person seated upon the support structure;

a frame attached to the support structure to support the upper body portion, when leaning back (backrest), which may be connected in such a way, that it allows for angle variations of the seated person forward or backward through a synchronized movement;

In the present embodiment the support structure is incorporated into a chair, in particular a work or office chair, on which the subject may recline backward or lean forward in a linear single movement, whereby the transverse pivotal axis is the knee joint as the reference fulcrum, meaning, while the upper thigh is evenly supported and in permanent contact with the seat pan surface in its entire length, the legs remain resting square on the floor. The compulsory dynamic movement allows the seated person to maintain throughout the motion a torso-to-thigh angle larger than 90 degrees. The incline of the seat pan is achieved and controlled by two pairs of transverse connected pivotally hinged levers directly under the seat pan, which force the seat pan to move on a compulsory hinged parallelogram with uneven legs to describe an imaginative curved path with the fulcrum in the knee joint.

The fact, that throughout the entire motion from a backward reclined position to a high forward inclined position, a torso-to-thigh angle of 100 degrees or more can be maintained, the need to alter the angle ratio between seat and backrest may be less relevant, since the primary function of the backrest is to support the upper body or torso, when it tips backward over its balance point into a reclining position. As a desire or need may occur to further open up the body angle closer to the zero posture (described further below), a backrest to seat angle adjustment can be incorporated through a compulsory synchronized movement with the seat pan movement. To be able to elevate a person into a higher forward leaning position, the seat pan needs to be supported by means of a force to lift a weight. There are several options for this force available, such as leaf springs, coil springs or pneumatic gas springs.

When installed with a lifting force in the form of a coil or leaf spring, the adjustable support structure would be a floating device, meaning, that with a corresponding adjustment of the spring to the weight of the seated person, the adjustable support structure would allow to balance the seated body and use the body weight to move into a forward elevated posture or into a relaxed backward reclining posture in a compulsory singular‘floating’ movement without obstruction or effort.

Furthermore, while a forward inclining posture modulates the upper torso weight forward and away from the uplifting force and thus requires less force, the opposite movement backwards toward a reclining posture requires more uplifting force as the upper torso weight falls back and increases with further recline. Thus there are also weight variations for one person with one particular weight, which require a positioning and characteristic of the uplifting force, that increases with the recline and lessens with the incline like in a progressive coiled spring or by doubling a leaf spring over the particular length required or by assisting a pneumatic gas spring with a progressive coil spring on its outer surface.

Finally, it may also be necessary, to lock the seat pan at a certain angle for more comfort. A person may be unfamiliar with the floating movement and feel insecure, or a higher precision in movement control is required for a task at hand. Thus, the adjustable support structure must also comprise means for securing (locking) the structure in particular infinite angular positions.

The means of locking can be achieved in several ways, either by a serial clutch plate block, locked transversely through a cam lever or by a screw-clamping device. The easiest means of locking the movement would be through a pneumatic gas spring with a lockable chamber valve.

In a preferred embodiment of the invention, the adjustable support structure would have only one releasable locking/detent means for the entire structure of the seat rest support and the arrest of the seat pan movement in anv inclination. A second means of lever or other device would be provided for the height adjustment and detention of the means of the uplifting force in portion (A) of the current embodiment.

The limitations of the terminal positions of the backward and forward movement of the seat pan can be controlled by various means, either by limiting the movement of the weight lifting device through the length of the slots it moves in, or, in case of employing a gas spring, the length limitation of its stem movement. The present embodiment is designed to accommodate the most common seating situations in the current office environment. It also provides a solution for the fast gaining recognition and importance, to employ height adjustable tables in the office working environment aimed to solve the back pain problems, by switching effortlessly between working in a low sitting position and an elevated high up working position with infinite positions in between.

In addition, the construction and movement of the present embodiment also offers to be applicable in many other situations, where a person needs an elevated seating support for various tasks, which traditionally can only be achieved with two or more different chairs.

To complement the description which is being made and with the aim of aiding to better un- derstand the features of the invention according to a preferred exemplary embodiment there-of, a set of drawings is attached as an integral part of said description, in which the following is shown with an illustrative and non-limiting character.

Brief Description of the Drawings

A preferred embodiment of the Invention will now be described (by way of schematic example), with reference to the accompanying drawings, in which:

Fig. 1 depicts a schematic view of an office chair construction in accordance with and comprising the present invention;

Fig. 2 depicts a schematic view of the anatomic premise which the current embodiment is referring to and its modulations in 2.1, 2.2 and 2.3;

Fig. 3 depicts a schematic view of the current common situation of seat structures offered to the marked at present, showing the angles of a generally backward tilted position and a generally horizontal position;

Fig. 4 depict a schematic view of the objective, which the current embodiment is

claimed to achieve, showing first a generally forward tilted and second an acute forward tilted position;

Fig. 5 depicts a side view of the assembly of the support structure and its members referring to the assumptions of Fig. 2, Fig. & Fig. 4 in the lower relaxed reclining position;

Fig. 6 depicts a side view assembly of the support structure and its members and proportions as shown in Fig 5, but raised to the acute forward tilted position and the fulcrum reference point of the knee joint; it also describes the proportions of the articulation of the present embodiment and the fulcrum reference point of the knee joint; Fig. 7 depicts the embodiment of the assembled apparatus of portion (B) in Fig. 1;

Fig. 8 depicts a section through the apparatus assembly shown in Fig. 7;

Fig. 9 depicts an isometric exploded view of the members of the in Fig.7 shown appara- tus assembly;

Fig. 10 depicts the preferred embodiment of the apparatus as an assembly of portions B,

C, D and E, e.g. apparatus, seat pan, armrest and backrest as described in Fig. 1, in a lower reclined position;

Fig. 11 depicts the preferred embodiment of the apparatus as an assembly of portions (B),

(C), (D) and (E), e.g. apparatus, seat pan, armrest and backrest as described in Fig. 1, in an acute forward tilted position;

Fig.l2 depicts the hinge arrangement between the apparatus (B) and the backrest (E) support lever, that controls the reverse synchronized movement of the backrest in relation to the seat pan in a reclined position;

Fig.13 depicts the hinge arrangement between the apparatus (B) and the backrest support lever, that controls the reverse synchronized movement of the backrest in relation to the seat pan in a forward tilting position;

Fig. 14 depicts the preferred embodiment of the present invention applied in an office chair in its most articulated positions.

Detailed description of the preferred embodiments of the Invention

It is also to be understood that the specific devices and processes illustrated in the attached drawings and described in the following specification are exemplary embodiments of the inven- tive concepts defined in the appended claims. Hence, specific physical characteristics relating to the embodiments disclosed herein are not to be considered as unnecessarily limiting, unless the claims expressly state otherwise.

Fig. 1 generally depicts an office chair and schematically represents a possible embodiment of the invention. As will be evident from viewing Fig. 1, the seating assembly generally corn- prises five elements:

a base (demoted A);

a support structure in the form of a mechanism (demoted B);

a seat pan (demoted C);

a support structure in the form of an armrest (demoted D);

a support structure in the form of a backrest (demoted E); The base A is structured as a classic 5 -prong rolling leg frame containing a telescopic column, which carries a gas cylinder, which can be adjusted in height in order to adapt to the specific requirements of each users height for such a seat support structure. The structure A acts as a mount, upon which the structure B is supported.

Mounted upon structure A is the support structure B and the seat pan C, which form the heart of this current invention and comprise a plurality of portions, which will be described in detail below.

Fig. 2, 2.1, 2.2, & 2.3 depict the biomechanical.background and explanation for the function of the current invention and describes part of the human skeleton, in particular the arrangement of the bone structure and movement around the hip joint. Fig. 2 shows the bones attached to the hip joint and its relative angles when standing up and when sitting on a seat surface at a 90- degree angle. It is today a scientific established fact, that the maximum angle of movement be- tween hip bone and pelvis is 60 degrees, while the remaining 30 degrees take place in the lumbar part of the spine directly above the pelvis, the result of which is a conversion of the natural spine curve (lordosis) into the opposite curve (kyphosis). Fig. 2.1 shows the so-called zero position, in which the natural spine curve is still maintained, while all muscles controlling the bending process, on the thigh, around the buttock and the lower back are in a relaxed state, neither tensed or depleted. Fig. 2.2 shows the typical seat configuration achieved with the majority of seating de- vices available in the market. Fig. 2.3 shows the actual configuration, when executing a task that requires a short distance between the eye and the object to be observed on a flat table, like in writing or drawing. In both cases the muscles of the lower back and the lower thigh muscles are increasingly tensed, while the upper thigh muscles are increasingly depleted.

Fig. 3 depicts the seating configuration and the corresponding torso-to-thigh angles of a traditional seating support structure in its most forward and most backward position and illustrates the effect of the limitation of seat support structures most commonly present in the market, whereas 3. a represents the pivotal location of the hip joint, the knee joint in 3.b and the pivotal point of the foot in joint 3.c, which remains stationary through the whole movement.

Fig. 4 depicts one of the claims and the aim of the current invention to modify the seating support structure in such a way, that a torso-to-thigh angle of 100 degrees or -more can be maintained throughout the entire elevation movement from the most lower back recline to the upper most forward incline. This should allow the curve of the spine in the lumbar region to be maintained as close as possible to its natural curve, which requires a forward tilting angle of the seat pan in alignment with the thigh corresponding to the knee joint; it also describes the angles, the current invention claims to achieve through the multi-pivotal levered elevation of the seat pan, whereas during the entire movement in the forward inclined position a lower-to-upper thigh angle of 100 to 110 degrees and in the lower backward reclined position a torso-to-thigh angle of at least 115 to 120 degrees should be maintainable.

Fig. 5 depicts a schematic illustration of the seating support structure and the portions in- volved to achieve the claimed angles and movements described above. The portions generally take the form of levers or like structures. In the illustrated embodiment the portions shown are:

1. representing the tip of the base support structure A (for example the tapered stem of a gas spring), onto which the support structure is mounted;

2. representing the support bearing structure for the pivotal attached levers and cradles the base mount of the base support structure in the form of a tapered conical shaft hole;

3. representing the lifting force device in the form of a lockable pneumatic gas spring;

4. representing the rear lower pivotal hinged lever of the parallelepiped;

5. representing the upper forward pivotal hinged lever of the parallelepiped;

6. representing the upper connecting support bar of the parallelepiped and the support- mounting base for the seat pan;

7. representing the connecting lever to the backrest;

In this embodiment of the invention, the various portions of the support structure are connected via hinge or pivot means, so as to define the support structure in a lower backward reclined position, whereas the uplifting force 3 is at its lower hinge point pivotally hinged to the bearing structure 2 in point 3.1 and at its upper end to the seat pan support in pivot point 3.2.

The upper forward pivotal hinged lever 5 is at its lower end hinged pivotal to the front of bearing base 2 in point 5.1 and at its upper end to the seat pan support 6 in point 5.2. The lower backward pivotal hinged lever 4 is at its lower point pivotal hinged to the bearing base structure 2 in point 4.1 and at its upper pivotal point to the seat pan support 6 in point 3.2/4.2. Also illustrated is the alignment of the seat pan (C) with the knee joint fulcrum 3.b (Fig. 3) and the positional parallel alignment to the knee joint in the higher upward inclined position.

Fig. 6 shows the support structure moved into a desired second forward inclined position and how it enables the subject supported by the structure to be moved from a relative lower backward reclining position to an acute elevated forward seated position (and vice versa), or to any position along a continuum between those two extremities. As is illustrated in this depiction, the range of movement between the first and any desired second position is controlled and limited solely by the extend of movement permissible of portion 3, the uplifting force device employed in accordance with the particular design of the support structure in use in any particular instance. It also illustrates the alignment of the seat pan (C) with the knee joint fulcrum 3.b (Fig. 3) and the positional parallel alignment to the knee joint in the higher upward inclined position.

Fig. 7 depicts the preferred embodiment of the apparatus assembly of portion (B) in Fig. 1, with its portions as described in Fig. 5 and Fig. 6. plus the additional portions of the release lever arrangements on each side for the seat height gas spring release lever 10 and the apparatus height lift lever 11.

Fig. 8 depicts an isometric section through the in Fig. 7 described apparatus assembly and its arrangement of the in Fig. 5 & 6 described portions and its referential hinge points in relation to each other.

Fig. 9 depicts an exploded isometric view of all portions comprising the apparatus assembly of portion (B) in Fig. 1 and described in Fig. 5, 6, 7 & 8. In addition it depicts the position of the release lever 8 with the hinge pin 8.1, the adjustment screw 8.2 for the release pin adjustment of the gas spring for the height adjustment in portion (A) in Fig. 1 and the release Bowden cable 8.3 connected to the release lever 11 (Fig. 7). It further depicts the arrangement of the cover 9 of the base structure 2.

Fig. 10 depicts the assembly ofportions (B), (C), (D) and (E) as described in Fig. 1 , 5, 6, 7,

8 & 9 in a lower rearward reclining position, describing the relative position of the portions of the parallelepiped, which allow a circular movement around the imaginary pivotal fulcrum of the knee joint.

Fig.11 depicts the assembly of Fig.10 in an acute upper forward raised position of the seat pan and the compulsory syncronized movement of the backrest portion (E) relative to the seat pan (C), whereby the backrest (E) stays in a vertical position allowing a seated person to keep the upper body balancing upright

Fig. 12 describes the mechanical arrangement of the connecting hinge arrangement between the backrest support structure 7 and the lower pivotal hinged lever 4, whereby the lever 4 hinged in 4.2 has an rearward extending cam with an oblong sliding hole in 7.2 which engages the backrest lever hinged in 7.1 by means of a transverse shaft in 7.2 fixed to the backrest lever.

Fig. 13 describes the in Fig. 12 shown arrangement in the upper forward inclining position and demonstrates the reverse movement of the backrest

Fig. 14 depicts the in Fig. 10, 11, 12, & 13 described movements of the backrest (E) and the seat pan (C) when applied to a complete chair as described in Fig. 1, in a rearward reclined position and a forward and upward inclined position. It also describes the objective of this invention to allow a movement of a person from a reclined lower backward position to a higher forward inclined position rotating around the knee joint fulcrum with constant contact of the upper thigh to the seat pan, thus maintaining sufficient friction and support on the seat to prevent sliding forward and while asuming an opening of the body angle approximating 120 - 125 degrees, which is close to the zero-position as described in Fig. 6.

In another not illustrated aspect of the current invention, the locking of the up or down movement of the support structure depends on the form of device employed for the uplifting force. If the force is generated by a progressive coil spring, the detention or locking could be employed through means of a multi-layered clutch plate block, which arrests the movement of the pivoted parallelogram levers by means of a cam-shaped lever, clamping (locking) or releasing the clamp plates transverse and thus allow the spring to extend or to remain stationary.