AN ERGONOMIC WORKING STATION

The number of persons who work whilst seated in a static posture, perhaps in front of a computer, is increasing progressively; as is also the number of hours in which such persons remain seated. Since the human body is not developed for purely static work, this type of work does not only result in an increasing degree of discomfort but is also liable to cause damage to the person's body, for instance muscle pains, attrition and other impairments. Although the causes of such injuries have probably not been fully investigated at the time of drafting this document, one of the factors involved is considered to be the reduced circulation in statically contracted muscles.

With the intention of improving ergonomics with respect to work that is carried out in a seated position there have been proposed over the years many constructions that provide effective adjustment possibilities so as to enable a working station to be adapted to suit precisely the person who shall use this station. In order to avoid, or at least reduce, purely static work, for instance with outwardly raised arms in the case of computer keyboard work, special wrist supports have been constructed (US 5,158,256). With the intention of enhancing circulation, there has been proposed furniture that has a built-in ability to make slight movements so as to enable a working position to be varied, for instance with the aid of a motor drive (US 6,296,408).

Improvement in the conditions of a statically seated worker with the aid of the measures involving the movement variations obtained by the continuous change of the working position with hitherto known devices is relatively small and the movements are not sufficiently dynamic to improve blood circulation to an extent required to reduce the danger of muscular pains among other things. Against this background, the object of the invention is to provide an arrangement with which circulation of the blood is improved as the work is carried out, as a result of continuous movement in the joints and muscles of the user's upper extremities.

This object is achieved in accordance with the invention by virtue of the work table, or a part thereof, which supports a keyboard being arranged to move along a movement path that extends down forwardly of the user. Moreover, the

slope or inclination of the work table or the keyboard is coupled so that the table or the keyboard can be angled in the movement direction at the same time.

By designing the work surface in the manner described above it is possible to position in particular the working surface of the keyboard relatively far from the body and relatively close to the body without the user feeling any discomfort. The angular regions within which hands and fingers work can be maintained at an optimum while enabling arm and shoulders to carry out relatively large movements that result in considerably improving circulation and corresponding improved comfort and well-being. On the other hand, continuous movement of a work table from and towards the body respectively in the same level results in a greater load on the spine and shoulder muscles when the work table (and the hands) are located farthest from the body.

With the intention of improving mobility still further during a working process, the keyboard may be arranged to also move backwards and forwards sideways.

It is conceivable within the framework of the invention for motorized operation to be achieved with the aid of cams, levers, etc or for the work surface to be movable along a guide means that is spring biased towards the user so that the user is able to press the work surface away from himself and so that the work surface will then slowly return, which can be achieved, for instance, with the use of a gas cylinder and a spring. The terminal positions can be determined with the aid of appropriate stops or by means of an appropriate length of stroke of the motorized arrangement. The work surface angling movement may also take place in conjunction with a terminal position stop means and the movement may take place at the same frequency as that of said work surface or at a different tempo. Movements of the work surface may also be program controlled.

Further developments of the inventive concept will be apparent from the accompanying claims and from the follow description of a preferred embodiment illustrated in the accompanying drawings, in which Fig. 1 illustrates a work station according to the invention seen from one side in a first position, and Fig. 2 illustrates the same work station in a second position.

The illustrated work station includes a table 1. The table edge that faces towards the user 10 includes an indentation in which there is received a small

work surface 3 that is movable in a path that extends downwards and in beneath the table, i.e. away from the user. The work surface 3 is suspended from pivot arms 4 and 5 mounted in a bracket 6 on the underside of the table and in a bracket 7 disposed on the underside of the work surface 3. An array of brackets and pivot arms is arranged at each end wall of the work surface. The pivot arms 4, 5 have mutually different lengths that result in a combined pivotal movement of the work surface 3 in a parallel manner. In the case of the illustrated embodiment, the work surface angles away from the user when the work surface moves forwards and downwards. As will be seen from figures 1 and 2, the angle between the user's hand and the work surface is maintained regardless of the angular forwardly displaced position of the work surface. This means that the user's hands 11 are able to maintain their position relative to the keyboard and to any associated support over the full movement path of the work surface 3, at the same time as the wrists of the user work at different angles in relation to the user's forearms. In this way, movement in the tendons that connect the fingers with associated muscles will be superimposed.

Also the elbow joints and the shoulders of the user will be continuously subjected to angular changes during the motorized movement of the work surface backwards and forwards between the positions shown in figure 1 and 2.

The motorization for achieving the reciprocating movement of the work surface can be effected with the aid of a link connected to a motor-driven eccentric element. An eccentric rotating position corresponding to the position of the work surface 3 in the plane of the table 1 can be detected with the aid of a sensor and the motor then stopped, therewith allowing the motorized work surface to be stopped automatically and returning to this position.

Movement of the work surface is restricted in its entirety by abutments and eccentric dimensions, and the length of stroke is beneficially variable between 0 to 40 cm in respect of the table and with a pivoting time period of up to 10 min. The work surface 3 is also movable sideways, which can take place in the work surface's own tempo or which may, alternatively, be synchronized with one of the two other movements. Instead of allowing the whole of the work surface to move sideways, it is conceivable to allow only a part of the work surface to move sideways and to carry or support a keyboard in a manner that is not disclosed.

Such sideways movement of the keyboard will ensure that the reciprocating movement of the arms will not pass exactly along the same path every time, therewith reducing the risk of wear while improving the blood supply.

The motorized movement or movements need not follow the same cycle every time, and the length of stroke and the turning points can be varied in time, for instance by reversing the rotational direction of the motor. This variation may also take place randomly.

Instead of a motorized arrangement, an arrangement is conceivable in which the user is able to the press the table away from him/her against the action of a spring. It is also conceivable for the table to include a limited spring effect in addition to the motor drive.

The desired movements and their respective movement areas may also be achieved with other movement elements than those described, for instance with the use of co-acting linear guides that permit varying movement paths to be achieved.

By avoiding a static working position, the work carried out is more comfortable and less tiring.