Work table for dynamic sitting with horizontally or diagonally cyclically variable worktop position.

Technical Field

This invention relates to the manufacture of an office desk or assembly table with emphasis on ergonomic seating and preventive protection of people against negative health effects of sitting for long periods.

Background Art

Negative effects of sitting for long periods, especially when performing office or assembly work, have been known for a long time. Manufacturers' focus has been on handling this problem in the area of seating, on the most perfect ergonomic chairs possible. Regrettably, one of the most effective solutions, consisting in the principle of balance seating, has not been widely used for work chairs because it requires interaction of the seated person. It is known that a healthy person underestimates the risk, and it is too late for those who have already back pain and similar problems. Some office desk manufacturers have tried to handle this problem by adjustable worktop height to ensure an ergonomic workplace. For example, invention WO9218033 (Al) of 1992 tackles this issue by electric motor adjustable table height, which can be changed by means of a controller. In addition, invention WO2015058768 tackles the seating ergonomics issue by changing the work table height for sitting and standing modes. The controller controlling electric motor drives of this table adjusts the work table height for the sitting or standing mode, including alarms warning that the mode needs to be changed. However, a drawback of this solution is that experiments have shown that a simple change of the worktop height does not fully solve the issue of health problems. This is because when the worktop height is changed reasonably, i.e. about 10 cm, the sitting person handles this difference by changing their forearm inclination, and partly by shifting their upper arms from the trunk. Subsequent changes in the shoulder position are small and changes in the spine position are negligible. Also in the sitting or standing modes in a configuration of the position of arms and the worktop similar to those in the previous mode (according to invention WO2015058768), the position of shoulders and the cervical spine does not change much. Another considerable disadvantage of the previous and similar solutions is the need for sitting person's interaction, whose work is thus disturbed. The aim of the present invention is to remedy the above deficiencies through such technical solution and application, which ensure trouble-free sitting at work also for long periods. Summary of Invention

The drawbacks above are remedied and the task set is met by a work table with a worktop adjustable using a set of devices with an electric motor according to preamble claim 1, which essentially consists in adjusting the positioning equipment set to achieve the horizontal or inclined patch of worktop displacement in the defined mode.

Experiments with a person sitting at the adjustable worktop have shown that positive effects on different spine and shoulder position following a horizontal shift in worktop position are substantially stronger than those following a vertical shift. Following a diagonal shift of the worktop, the effects of each change sum in synergy, and the total positive effect on muscle load in the spine, neck and shoulder area is the greatest. The essence of this invention is enabling a continuous change in the worktop position in the horizontal or approximately diagonal directions.

It is preferred to set the worktop position change mode without sitting person's assistance so that this sitting person's activity is not disturbed by such worktop position change. To ensure an imperceptible, very slow rate of worktop position change (about 6 cm/min. - 6 cm/60 min.) and, if possible, continuous change of worktop position when moving from the starting position to the final position within the range of about +-5 cm, a standard controller has been designed with internal or external timers with set time intervals for each worktop position, which switches on and off the electric motor unit.

It is preferred to use a low-power electric motor unit that can be connected with a gear reducer, which has a positive effect on the acquisition cost, power consumption and reduced noise.

There is a preferred solution, in which the electric motor unit consists of a rotary engine (stepper, single-speed motor, etc.) with a brake. The motor is fixed to the worktop beam, has a double-sided shaft with pinions on each end, with mechanical linkage with the guide-way rack bars fixed on the table frame. This causes that the mechanical transmission ensures a precise, parallel worktop movement. This solution prevents the worktop from twisting during movement, or due to imprecise motor switching and braking. This solution also ensures reduced acquisition cost as the less precise motor unit is considerably cheaper. Despite the advantages above, in some cases it may be more preferable for design and space reasons to use a pair of linear motors that replace the electric rotary motor with a double-sided shaft and pinions and rack bars.

It is preferable to build the electric rotary motor with a double-sided shaft in a reinforcing tube with anti-noise and anti-vibration treatment that connects the worktop beam sides. As a more frequent use of the drive unit is expected when using this invention than in other inventions from the similar field, the lowest possible noise and vibrations are important criteria.

It is preferable to fit the worktop beam with rolling or sliding bearings that move in the guide-way groove fixed on the table supporting frame and ensure a precise relative position of moving and fixed parts of the positioning equipment set, prevent lateral worktop displacement and ensure stability of the whole table.

It is preferable to fix the fixed table frame with the (horizontal) guide-way on at least two electromechanically, vertically extensible legs, and ensure optimum movement path by combined movement in the vertical and horizontal directions.

It is preferable to install in the room a movement sensor (photocell), which monitors the presence or absence of the sitting person independently of the sitting person at regular intervals and depending on that switches the positioning equipment set on or off.

Another essence of this invention is its application, consisting in releasing the sitting person from any participation in worktop position changes, which is, according to the invention, ensured by the controller with a pre-set activation system that ensures, after a pre-set time of sitting at the work table in the starting position, a slow, if possible imperceptible continuous change of the worktop position to the end position and back, to which the sitting person adjusts subconsciously, thus keeping relevant body parts in a hardly noticeable but continuous movement where the spinal curvature, position of shoulders and back muscles are changing, which has a major positive effect on ergonomic seating and prevents health problems of the upper body part musculoskeletal system. It is preferable that more than 50% basic schedule is spent by the person sitting at the worktop in a position close to the basic setting, which corresponds to standard ergonomic parameters (i.e. worktop height of about 75 cm).

This invention application eliminates the common problem based on empirical evidence consisting in the fact that all manufacturers' ergonomic recommendations for proper use of adjustable chairs or tables requiring sitting person's involvement are ignored over time due to current convenience or focus on another activity. Constant changes of the worktop position avoid muscle stiffness, the load on each muscle group changes, which clearly has a beneficial effect on the sitting person.

For different work activities or physical therapy, it is preferred to set different optional modes of time intervals for worktop position changes, including different changes of rates of worktop shift or permanent cyclic worktop shift. This solution may be commonly used in assembly line tables, for example, where adequately set time and speed program corresponds to the assembly operating program. Another use is a faster cyclic change of worktop position, even several times a minute, with a therapeutic effect on the upper body muscles.

Brief Description of Drawings

The appended drawings show an example of embodiments, where each figure represents: (electric installations are not shown)

Fig. 1 - View of a stationary table frame for horizontal guide-way fixing

Fig. 2 - View of a stationary table frame for diagonal guide-way fixing

Fig. 3 - Detail view of a guide-way with all co-operating elements

Fig. 3a - Detail view of a guide-way with linear motor

Fig. 4 - View of general arrangement of the positioning equipment set

Fig. 5 - View of a complete table with horizontal arrangement

Fig. 6 - View of a complete table with diagonal arrangement

Fig. 7 - Side view of a sitting person at the worktop in the basic ergonomic position

Fig. 8 - Side view of a sitting person at the worktop in the bottom and outermost position

Fig. 9 - Side view of a sitting person at the worktop in the top and nearest position

Fig. 10 - Bottom view of the table frame fixed on vertically extendable legs

Fig. 11 - Bottom view of the arrangement with linear motors and vertically extendable legs

Examples of Embodiments

As it is apparent from the appended figures, two types of configuration have been designed, with horizontal worktop 5 shift and with diagonal worktop 5 shift that only differ in table frame 1 arrangement, as shown in Fig. 1 and Fig. 2. The other components for the positioning equipment set with rotary electric motor unit 3 are identical. If a linear electric motor unit from Fig. 3a is used, the horizontal configuration differs from the diagonal configuration also only in the table frame configuration. It follows from Fig. 3 and Fig. 4 that two mirror-symmetrical guide-ways 11 are fixed on the table frame 1 sides. To ensure the side guide-way 11 offset from beam 2, the guide-way 11 has distance bearings 112. A fixed part of the guide-way 11 is the rack bar 111 that helps create the guide groove 113 in the guide-way 11 outside the geared transmission. Travelling bearings 211 put on beam 2 holders 21 are slid into these guide grooves 113, followed by distance bearings 22 fixed to the beam 2 (they also provide a stable side offset), and the geared pinion 312 on the shaft 31 is mechanically linked with the rack bar 111. At the end of shaft 31 there is a travelling bearing 313 which, by travelling in the guide groove 113, ensures optimal relative position of the geared pinion 312 to the rack bar 111. Both beam 2 sides are interconnected by the tube 32 with the electric motor unit 3 fixed in it, specifically a stepper motor with transmission and brake, connected with a double-sided shaft 31. The shaft 31 is mounted on both front walls of tube 32 by means of the bearing 311.

This and additional similar arrangements can be supplemented by at least one pair of vertically extendable legs 12 with electromechanical drive 121, on which the table frame 1 is mounted, as shown in Fig. 10.

As it is clear from Fig. 3a and Fig. 4a, two mirror-symmetrical guide-ways 11 in the configuration with linear motor are fixed on table frame 1 sides. To ensure the side guide-way 11 offset from beam 2, the guide-way 11 has distance bearings 112. The electric motor unit 3 is fixed to the guide-way 11, in this configuration it is a linear motor with a shifting carrier 33, wherein the rear wall of the electric motor unit 3 is part of the guide groove 113. Travelling bearings 211 put on beam 2 holders 21 are slid into these guide grooves 113, and the beam is also connected with the carrier 33 of the electric motor unit 3.

Fig. 5 and Fig. 6 show the complete arrangement in horizontal and diagonal configurations. The worktop 5 is fixed on the beams 2. Installed on the table frame 1 is a sensor 41 monitoring the sitting person's feet area, and attached to the table frame 1 is also a controller 4 with timers 42 connected to the power supply, sensor 41 and electric motor unit 3, specifically a stepper motor with transmission and brake. Electric installations are not shown in the figures.

The controller 4 that normally controls linear motors, including stepper motors, is adjusted with software and supplemented by timers 42 such as type NE 555 to be set to the mode of activation pulse receipt from the movement sensor 41. Depending on the pre-set mode A, B or C to be selected with the switch 43, the controller 4 transmits commands to switch the electric motor unit 3 or electromechanical drives 121 on or off. Fig. 11 shows the arrangement with at least one pair of vertically extendable legs 12 with electromechanical drive 121, on which the hollow-profile table frame 1 is mounted, which has two electric motor units 3 seated in parallel inside, specifically electronic synchronized stepper motors with motion screw carrying in the guide groove 113 sliding bearings 311, on which beams 2 of the worktop 5 are mounted as shown in Fig. 10.

Examples of Invention Application

Fig. 7 shows a sketch of a person sitting in the recommended ergonomic position at the table, the worktop 5 of which is at a level of 75 cm from the ground. The sitting person's feet are in the sensor's 41 sensory area. The sensor 41 transmits the control signal at regular intervals such as every 3 min. Depending on the response, the controller 4 switches from the standby mode to the operating mode, and depending on the pre-set mode A, B or C, the controller 4 transmits commands to switch on or off the electric motor unit 3, which drives, in this case, the double-sided shaft 31 with geared pinion 312 that rolls on the stationary rack bar 111 to defined offset positions from the starting position, thus carrying the beams 2 with the worktop 5. If the sensor 41 does not sense any sitting person, then the controller 4 ensures that the worktop 5 goes back to the starting position and the controller 4 switches to the standby mode.

The invention application with the pre-set mode A ensures that following controller 4 activation by the signal received from the sensor 41, a series of tripping signals is transmitted from the controller 4 to the electric motor unit 3 after about 15 idle minutes counted by the timer 42 to ensure the shift of worktop 5^ for example, by 5 cm to the outer and by 5 cm to the farther positions in 10 min. The sitting person is made to slightly drop their shoulders down, extend arms and bend by about 10 degrees. The person does all this subconsciously, if their hands are, for example, on a computer keyboard as shown in Fig. 8. When the full downward limit is reached, the worktop 5 returns to the starting position, at the same rate for example, where it remains for about 15 min., for example. After this idle period counted by the timer 42, a series of tripping signals is transmitted from the controller 4 to the electric motor unit 3, thus ensuring the shift of worktop 5 to the outer top position by 5 cm and to the outer nearer position by 5 cm in 10 min. The sitting person is made to slightly lift their shoulders, shift them slightly backwards, bend their head forward and bend the trunk backward by about 10 degrees from the starting position as shown in Fig. 9. When the outer top limit is reached, the worktop 5 returns to the starting position, at the same rate for example, where it remains for about 15 min., for example, till the next cycle. This way ensures that the sitting person's muscular system is continuously stretched with all positive effects. Unlike mode A, the invention application with the pre-set mode B ensures that the worktop position changes only in one selectable direction. This application may be preferred for some types of sitting person's work activities.

The invention application with the pre-set mode C ensures a continuous change in the worktop 5 position for the sitting person, without any stops in the starting position, at a selectable rate of worktop displacement. This application may be preferred as a certain form of physical therapy exercise.

The modes above may be modified by a combination of worktop 5 movement using the electric motor unit 3 and stationary table frame 1 vertical movement using electromechanical drives 121.

List of Reference Signs

1 table frame 11 guide-way

111 rack bar 112 distance bearing

113 guide groove 12 vertically extendable leg

121 electromechanical drive 2 beam

21 beam holder 211 travelling bearing

22 distance bearing 3 electric motor unit 31 shaft 32 tube

311 sliding bearing 312 geared pinion

313 travelling bearing 33 carrier

331 motion screw

4 controller

41 sensor 42 timer

43 switch 5 worktop