Horizontally supported planar surfaces – Vertically adjustable – With force-multiplying means
Reexamination Certificate
1999-04-07
2001-04-24
Cuomo, Peter M. (Department: 3624)
Horizontally supported planar surfaces
Vertically adjustable
With force-multiplying means
C248S123110
Reexamination Certificate
active
06220185
ABSTRACT:
BACKGROUND
The invention relates to a table, in particular for video workstations, having a height-adjustable tabletop with at least one vertical guide strut, furthermore having a table frame with at least one table support for the guide strut which telescopes within it, and having at least one adjustable spring leg which is arranged between the table frame or the table support and the height-adjustable table elements and has a spring on the inside, the adjustable spring leg being coupled, with its one spring end, in a positionally fixed manner to the table frame or the table support and being supported, with its other spring end, in an adjustable manner against a spring-leg base which varies the pretension of the spring and is connected to the height-adjustable spring elements, and it being possible for the spring-leg base to be locked in positions matched to differing loads on the tabletop by means of an attached adjusting device.
A table of the type of design described at the beginning has been disclosed by DE 38 17 102 C2. Such a table can, of course, also be realized with a multiplicity of tabletops instead of one tabletop. Structures on top of the tabletop, such as, for example, shelving, cupboard elements etc. are also conceivable. The tabletop and guide strut (or guide struts) generally form the height-adjustable table elements whereas the table frame and table support remain fixed in position.
In the case of the known table, which the invention takes as the starting point, height adjustment is brought about by the tabletop being kept in suspension by means of the adjustable spring leg. For this purpose, use is made of the adjusting device which matches the spring-leg base to differing loads on the tabletop. In the case of the known teaching this matching is done in such a way that the adjusting device for the spring-leg base or the supported spring end of the adjusting spring leg is designed as a spindle drive with a handwheel or crank. All in all, a mounting which is, as it were, suspended is realized for a height-adjustable table whose tabletop can—because of the suspended state—be adjusted in height with minimum effort by a relevant operator. After the desired position of the tabletop has been reached, the latter is generally fixed via a (manually operable) locking brake.
The measures described above have proved their worth per se but, as far as the weight counterbalance or the reaching of the suspended state are concerned, are in need of improvement. For one thing, manual adjustment of the adjusting spring leg or of the spring-leg base thereof no longer meets today's requirements for convenience and, for another thing, inaccuracies are associated with the manual adjustment and, in particular, flexible and rapid matching to changing loads on the tabletop is achieved only with a great outlay. In addition, if the weight is not completely counterbalanced and the locking brake is released risks to the operator cannot be ruled out. This is where the invention comes in.
SUMMARY OF THE INVENTION
The invention is based on the object of developing a table, in particular for video workstations, of the type described at the beginning in such a manner that simple, convenient, safe and flexible matching to changing loads on the tabletop is made possible.
To achieve this object, in the case of a table of the generic type, in particular for video workstations, the invention proposes that a measuring device for determining the particular load on the tabletop is provided, and that the adjusting device is correspondingly activated as a function of load values determined. Generally, the measuring device and adjusting device form a closed control loop for this purpose. In addition, an open-loop control device for evaluating the load values supplied by the measuring device and for the corresponding activation of the adjusting device can be provided. This open-loop control device can, of course, also be a closed-loop control device. The measuring device is preferably designed as two or more switches which are assigned to a rotating rod, the rotating rod being connected to the guide strut and converting the vertical movements thereof into rotational movements, and rotations of the rotating rod being transmitted to the one switch or the other switch, depending on the direction of rotation of the rotating rod, via an attached connecting element, for example an extension arm. It should be emphasized that, according to the teaching of the invention, it is not only possible for the guide strut to carry out vertical movements in the sense of telescoping in the associated table support but it is also possible, of course, within the framework of the invention to carry out “oblique positions” of the guide strut, on the one hand, and the table support, on the other hand. In any case, such linear displacements of the guide strut in the table support are intercepted via the rotating rod and converted into corresponding rotational movements. The same is, of course, also true for the case in which—as is customary—at least two guide struts with associated table supports are realized.
In this connection, the extension arm can be attached to the rotating rod by means of a sliding bearing, and, when the rotating rod is rotated, can strike against the switches, which act as stops, with either the one switch or the other switch being struck, depending on the direction of rotation. This enables the simple and, at the same time, height-independent measurement of the particular load on the tabletop. This is because as long as the rotating rod strikes against a switch with its extension arm, it can be ascertained via this switch actuation that the tabletop is moved up or down by the guide strut. In order to ensure a corresponding weight counterbalance it is now—after the switch has been actuated—merely necessary additionally to activate the adjusting device in such a manner that the adjusting spring leg or a spring-leg base thereof is suitably positioned. For example, in the case of an upward movement of the tabletop by the guide strut it is to be assumed that the weight of the tabletop and any objects lying on it is overcompensated, with the result that the pretension of the spring has to be reduced by means of the adjusting device and the spring-leg base which can be varied thereby. This takes place until the extension arm strikes against the other switch and consequently the weight is (under) compensated and the extension arm alternately abuts or strikes against both switches.
In the event of the tabletop being moved downward by the guide strut, the procedure is carried out in a correspondingly opposing manner, i.e. the pretension of the adjustable spring leg is increased in order to counterbalance the weight undercompensation which is present here. It is always ensured that a (vertical) movement of the tabletop -with the locking brake released corresponds to corresponding variations of the spring-leg base so that the weight is counterbalanced in a simple, convenient and flexible manner. This is of particular importance nowadays since the service life of tables, in particular video workstation tables or else CAD tables, generally far exceeds the useful life of corresponding electronic (computer) components. Moreover, additional pieces of equipment are often required, and thus flexible matching to the weight ratios prevailing in each case on the tabletop is possible. In addition, particular emphasis must be given to the fact that operational safety can clearly be increased compared to the prior art. In actual fact, in the case of the known table and an insufficient weight counterbalance and also a released locking brake there is the risk of the tabletop—acted upon by the adjustable spring leg—leaping up and in the worst scenario being able to injure the operator. In any case, such risks no longer need to be feared since leaping up of the tabletop is automatically retarded or suppressed because such a vertical adjustment registers via the two switches and corresponding countermeasures in the form of chan
Anderson Jerry A.
Cuomo Peter M.
Fleischer Büromöbelwerk GmbH & Co. KG
Friedman Siegelbaum LLP
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