The invention also concerns a procedure for interactive communication for controlling and guiding the vertically adjustable column.

The prior art Vertically adjustable columns and similar constructions have existed for a considerable time and are used in various fields of application. The principles of construction have varied throughout the years. as has the material used in the construction.

There is a need in industry to use variable height for assembly facilities and workplaces.

Recently, it has been realised that there are advantages in adapting the height of a workplace to the type of work, the physical conditions of an employee and his or her wishes, in various types of office workplace. in particular since ergonomic requirements have received a greater attention. As part of this adaptation, the possibility of changing the working height of, for example, a desk is a considerable advantage.

Summary of the invention A device of the type described in the introduction is principally characterised according to the invention in that it includes at least three tube elements in the form of an outer tube, a central tube and an inner tube, that are provided with sliding surfaces for mutual guidance along at least part of the tube sides that face each other. whereby each tube has a first end that faces the first end of the column, and a second end that faces the second end of the column. and that the operating mechanism at the first end is attached to the side of the first end of the outer or inner tube that faces away from the central tube, and at the second end is connected to the second end of the central tube, and that one end of a chain or cable, in the form of a wire or similar, is attached to the second end of the outer or the inner tube, respectively, runs over a freely rotating pulley that is attached to the second end of the central tube, and then runs between the central tube and the inner or the outer tube, respectively, after which the second end of the chain or cable is attached to the first end of the inner or the outer tube, respectively.

With reference to modifications of the device described in the preceding paragraph,

particular attention is drawn to the non-independent claims. Furthermore, claim 2 describes an alternative embodiment of the new construction. In addition, a method for controlling the vertically adjustable column is defined in the claims.

Some form of operating mechanism, principally of an electrical type in the suggested and described embodiments, is used in the new construction for regulating the column in the direction of greater length, and with it a table surface or similar surface that rests on it. Naturally, other types of operating mechanism, for example, in the form of a gas- spring, and other principles of regulation can be used.

A number of advantages are achieved by the invention when compared to earlier known technology. Thus, the operating mechanism is actively used to increase the length of the column, while decrease in the length of the column, during which the operating mechanism is regulated in the opposite direction, is achieved by the action of gravity on the upper parts of the column in an upright or tilted position, opposed only by the low friction between the moving parts of the column when the wire is slackened. The lower speed of return depends of the degree of friction between the elements that comprise the column. The operating mechanism reacts to signals to it that are activated manually or automatically in a manner that is well known, according to a predetermined procedure.

The vertically adjustable column constructions that have been demonstrated previously have fewer than three mutually adjustable elements in a known arrangement, and the operating mechanism has a double role: it actively displaces the column elements out of each other in order to increase the length of the column, and it actively pulls the column elements into each other in order to decrease the length of the column. Thus, these constructions allow a maximum length of travel that is the same as the length of travel of the operating mechanism used, or a maximum length of travel that is the sum of the lengths of travel when two operating mechanisms are used, when these are arranged to operate in two opposite directions along the longitudinal axis of the column.

The use of a chain or cable, for example a wire, allows a change of length of the column that is larger than the maximum length of travel of the operating mechanism that is used. The maximum length of travel of a known type of construction of this type of column is 600 mm using the double-acting known wire solutions and the lowest height is limited to approximately 600 mm, the wire then actively drawing the column both upwards and downwards, the wire passing over two pulleys or wire wheels.

One double-acting wire or two wires have been used for displacement of the elements that comprise the column in cases in which the column consists of more than two

elements, and two motors have been used to influence the one double-acting wire or the two wires. Not only does this give a higher production cost, but also more parts to maintain and a construction that requires more space.

Furthermore, the risk for crushing injuries is greater when using double-direction column regulation since both column movements are influenced by an active force, which is not the case for the current invention in which the motion that gives a reduction in the length of the column is passive. In the latter case, reduction of the column length occurs by the action of gravity on the column, which depends on the weight that rests on the lower element of the column. The force is opposed in this case by the friction that has been adjusted by the adjusting screws that regulate the mutual friction between the elements of the column. However, the maximum speed with which gravity is allowed to apply freely is always limited by the construction by the speed of the operating mechanism that moves the end-points closer to each other, which means that the normally slack wire has a braking function which ensures safety.

The column elements that comprise the new construction can consist of various materials, for example, steel, aluminium. wood, plastic. composite material or similar. The shape of the cross-section of the column elements can have various geometric forms, for example, square, rectangular, triangular, circular, oval, or it may have more than four sides, and all the elements comprising each column do not necessarily need to have the same form.

For example, the inner element may have a circular cross-section, the central one a triangular cross-section and the outer one a square cross-section. Furthermore, the construction can consist of a combination column for control of a table top with two elements that can be separately regulated on which the table top is jointed so that it is suspended on angled brackets, whereby the angle of tilt of the table top and its height depend on the influence of two separately controlled operating mechanisms on the respective inner element. The adjustment of these can occur manually in each given situation, or automatically using predetermined parameters according to an embodiment described below.

The pre-treatment that is carried out, for example milling or grinding, during manufacture of the column elements in order to achieve the high parallelism that is required for the material surfaces that will form the running surfaces between the different column elements means that there is less friction between neighbouring elements. Furthermore, the surfaces that face each other can be coated with a low-friction material such as teflon, in order to reduce friction, giving excellent sliding surfaces. Other materials with equivalent

properties, such as nylon, delrin, etc., can, of course, also be used. Furthermore, the tolerance in dimensions and the stability, and through these also the running friction, can be adjusted for each surface of a column element with help of the adjustment screws that also hold the plate that is screwed on along the longitudinal axis of the column, and onto which the low-friction material is applied, in the correct place between the column elements. As the sliding surfaces are worn over the years, the stability and degree of friction of the column can be maintained relatively constant by a simple adjustment of the adjustment screws. This means that the lifetime of the column can be maximised, and thus maintenance costs minimised. In addition to this, the lower friction between the column elements requires less lifting power than previously known technologies, and thus a relatively lower loading and thus smaller dimensions are achieved for the operating mechanism used and for other parts included in the construction. Furthermore, gentle and even displacements of the column during movement are achieved for the same reason.

In terms of performance, the solution according to the invention with a single wire acting in one direction that runs over a pulley and is drawn by an operating mechanism, and with a three-part column construction, together with an operating mechanism that is known from earlier, means that a column length of travel of 700 mm is achieved, that is. 100 mm greater than using previously known technology, in the region of regulation from 600 mm to 1,300 mm. This makes it possible to use the construction according to the current invention at a workplace where it is desired to work both in a sitting and in a standing position.

Brief description of the drawings An embodiment of the current invention will be described below with reference to the attached drawings, where Figure 1 shows a cross-sectional view parallel to the longitudinal axis of the column according to the invention, reproduced when at its minimum length; Figure 2 shows a cross-sectional view parallel to the longitudinal axis of the column according to the invention, when extended; Figure 3 shows a cross-sectional view at right angles to the longitudinal axis of the column according to the invention, along the line A-A in Figure 1, reproduced when at its minimum length ; and Figure 4 shows a block diagram of an advantageous embodiment of the invention.

The embodiments of the invention described in more detail below, however, should be regarded only as examples and are not in any way to be considered as limiting for the

execution of the invention.

Detailed descriptions of preferred embodiments An advantageous embodiment of the invention consists of a one-directional column preferably for use at an office workplace in the form of a desk or similar. The column includes at least three tube elements 1,2 and 3 that can slide within each other. The position of the column can vary from totally upright to leaning to various degrees, but it is normally vertical, which gives the maximal influence of gravity on the column when the column elements return from an extended position. An operating mechanism 7, placed on the outer surface of the outer element 1, is used to increase the length of the column. The operating mechanism can also be placed on the inner surface of the inner element 3 in an alternative embodiment. The operating mechanism, which in this case is electrical, is activated manually, for example using an operating unit that is connected to the operating mechanism.

Only the case in which the operating mechanism 7 is placed on the outer surface of the outer tube 1 and in which all elements 1-3 consist of tubes will be described in the following.

One end of the operating mechanism 7 is attached to a first attachment 13, which in turn is screwed onto the upper end of the outer surface of the outer tube 1 by screws 25, while the other end of the operating mechanism 7 is attached to a second attachment 10 for a pulley 12, whereby the latter attachment 10 is in turn attached to the lower end of the central tube 2. A wire 28 runs from a third attachment 16, which is screwed onto the lower end of the outer surface of the outer tube 1 by screws 26, round the pulley 12 and then between the central tube 2 and the inner tube 3 up to the upper part of the inner tube 3. There the wire 28 passes through a hole in the inner tube 3 where it is attached to the inner surface of the tube by a peg 14. When the column is activated from its contracted position using control signals to the operating mechanism 7, the wire 28 causes the inner tube 3 and the central tube 2 to be displaced relative to each other. At the same time, the central tube 2 is also displaced relative to the outer tube 1. The total effect thus is that the three tubes 1-3 are drawn apart and the length of the column increases with a speed that is much higher than the speed of motion of the operating mechanism 7, through the"gearing"of the wire 28 and the pulley 12.

No active influence of the operating mechanism 7 takes place on the wire 28 during adjustment of the column in order to reduce its length. The moving end of the operating mechanism, however, is displaced so that the wire 28 becomes slack and in doing so allows

the tubes 1-3 of the column to slide within each other by the action of the weight from above, from, among other things, the table top that is normally attached to the upper end of the column (not shown). The contraction of the column is opposed by the friction that arises between the elements that are included according to the description.

Elongated plates are arranged vertically on the inner surfaces of two of the tubes 1 and 2 in order to reduce friction and allow adjustment of the force of contact between the tubes 1-3. The plates 19 are manufactured from steel and have strips 23 of teflon glued onto the inner surface of the column, facing the tube surfaces that have been pre-treated by milling or grinding. The purpose of the pre-treatment is to increase the parallelism and to reduce surface friction between the tube elements. The individual friction and thus the speed for shortening of an extended column is regulated by adjustment from the outside of the column of the screws 20 with which the plates 19 are attached, and in this way adjustment of the position of the plates at right angles to the longitudinal axis of the column elements.

Furthermore, there are elongated strips of teflon with sliding surfaces 23 associated with the two other corners of the other two sides of the two outer elements 1 and 2. These strips are glued onto the tube elements, and have a low friction surface facing inwards towards the adjacent tube element with the aim of reducing friction between these sides of the facing elements. This arrangement means that the inner tubes 2,3 are placed eccentrically relative to the central axis of the column.

In another embodiment, in which a column according to the description of the invention is used in direct association with a workplace, for example in an office environment, a more automatic function can be used as described below, with the aim of improving ergonomy for the employee.

There is generally a computer (not shown) in office workplaces today, which is used during work. According to the invention, an output from the computer is connected through an interface means 31 to the input of a separate means of conversion 32 that is included in the system and that also contains a control unit, which can be acquired as an accessory to the column described earlier. Manoeuvring cables are connected to the output of the means of conversion 32 for an electrical signal or similar to be sent to the operating mechanism 7 of the column.

When a person arrives at the intended workplace described above to begin a work- period, the person specifies a personal login code or similar, after which the work-table is automatically adjusted to a predetermined height. This predetermined height can be adapted to the individual and determined by an employee or employer or by both in consultation, or

it can follow recommendations from a body providing a company health service taking into consideration the height of the person, the work position (sitting or standing), any physical limitations, ergonomic requirements or the wishes of the employee. The pre-adjustment is made to that position that best agrees with the requirements for an optimal ergonomic workplace environment or other requirements in each individual case.

The said person can adjust the height adjustment based on the predetermined value as needs change during the work period. The person may find it convenient, for example, to work in a standing position during a particular operation or during part of the work-period. It may be that the person is troubled by muscular-skeletal aches. which means that a constant work position involves extra loading and complications. In these cases, the person can click on, for example, a special icon or image (that may for example have the appearance of an upward-pointing or downward-pointing arrow or a simple image of a table surface that is seen supported by a central column or similar) using a pointing device, which may, for example, be a computer mouse with buttons (a mouse pointer), a joy-stick with buttons, or similar. The icon, which may, for example, be placed in one corner of the computer monitor, is associated with an image of size a few square centimetres, with a vertical scale on which one can use the mouse pointer to click on a mark to give a command for raising or lowering the working height of the table surface. Following a choice by clicking or other method of giving commands using the mouse pointer, the desired number of electrical pulse signals or a certain voltage level, for example, are transferred through the interface means 31 of the computer and the means of conversion 32 to the operating mechanism 7 of the column so that the desired height adjustment is carried out. All conversion of electrical signals and adaptation of energy type, of whatever form it may be, from the signals sent out from the computer to the operating mechanism 7 of the column occur via the special means of conversion 32 that is part of the system. The function for control of the signals of the means of conversion 32 is realised in software, which may be complemented by hardware for the interface means 31 that is connected to the computer in question.

The login procedure described above may, of course, be omitted if so desired, depending, for example, on the nature of the work, practice at the workplace and so on, in which case only the icon function described above is used to change the position of the work surface.

The invention in another embodiment can also include the possibility of controlling, for example, a table surface using several columns that in a synchronised manner regulate the height of the table surface, and can also set it at an angle by a co-

ordinated lifting movement to the desired position for the table top that is resting on the columns. In addition to the embodiment described above with control of the column using a pointing device, control of several columns for height and angle adjustment can also occur according to the same principle with extended icon, image and scaling functions for clicking and giving further commands with the mouse pointer.

The column can consist in another embodiment of more than three (for example four) elements, while having essentially the same construction, by which two cables according to the description above are used for influencing the elements. Normally, two operating mechanisms are used in this case for manoeuvring the cables.

The embodiments of the present invention described above are preferred embodiments and are not given with the aim of limitation, which is why many variants of embodiments within the framework of the claims can be envisaged for one skilled in the technical arts. In this way, it is of course possible to replace the construction of the inner tube of the column with a solid. that is, homogeneous, element. The invention can of course be used in other fields than an office workplace, such as for industrial applications and in diagnostic and therapeutic applications in health and medical care.